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Louisiana Rice Production HandbookLouisiana Rice Production HandbookLouisiana Rice Production HandbookLouisiana Rice Production HandbookLouisiana Rice Production Handbook

ForewordForewordForewordForewordForewordClayton A. Hollier

Introduction......................................................................................................................4Steven D. Linscombe

General Agronomic Guidelines.......................................................................................4Steven D. Linscombe, John K. Saichuk, K. Paul Seilhan,Patrick K. Bollich and Eddie R. Funderburg

Growth and Development of the Rice Plant...............................................12Growth and Development of the Rice Plant...............................................12Growth and Development of the Rice Plant...............................................12Growth and Development of the Rice Plant...............................................12Growth and Development of the Rice Plant...............................................12Richard T. Dunand

DD-50 Rice Management Program............................................................20DD-50 Rice Management Program............................................................20DD-50 Rice Management Program............................................................20DD-50 Rice Management Program............................................................20DD-50 Rice Management Program............................................................20John K. Saichuk, Steven D. Linscombe and Patrick K. Bollich

Rice Varieties...........................................................................................23Rice Varieties...........................................................................................23Rice Varieties...........................................................................................23Rice Varieties...........................................................................................23Rice Varieties...........................................................................................23Kent S. McKenzie, Steven D. Linscombe, Farman L. Jodari,James H. Oard and Lawrence M. White III

Soils, Plant Nutrition and Fertilization......................................................32Soils, Plant Nutrition and Fertilization......................................................32Soils, Plant Nutrition and Fertilization......................................................32Soils, Plant Nutrition and Fertilization......................................................32Soils, Plant Nutrition and Fertilization......................................................32Patrick K. Bollich, John K. Saichuk and Eddie R. Funderburg

Pest Management.....................................................................................37Pest Management.....................................................................................37Pest Management.....................................................................................37Pest Management.....................................................................................37Pest Management.....................................................................................37Weed ManagementDavid Jordan and Dearl E. SandersDisease ManagementDonald E. Groth, Milton C. Rush and Clayton A. HollierInsect ManagementDennis R. Ring, James Barbour, William C. Rice, Michael Stoutand Mark MueggeBlackbird ManagementJames F. Fowler and Joseph A. Musick

Harvest and Storage................................................................................95Harvest and Storage................................................................................95Harvest and Storage................................................................................95Harvest and Storage................................................................................95Harvest and Storage................................................................................95Harvesting RiceWilliam A. HaddenRice Drying and StorageDouglas L. Deason

Rice Economics........................................................................................100Rice Economics........................................................................................100Rice Economics........................................................................................100Rice Economics........................................................................................100Rice Economics........................................................................................100L. Eugene Johnson, G. Grant Giesler and Michael E. SalassiFarm ManagementMarketingU. S. Farm Policy for Rice

GlossaryGlossaryGlossaryGlossaryGlossary..................................................................................................110..................................................................................................110..................................................................................................110..................................................................................................110..................................................................................................110

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ForewordForewordForewordForewordForewordClaClaClaClaClayton yton yton yton yton A.A.A.A.A. Hollier Hollier Hollier Hollier Hollier

Rice has been produced in Louisiana since the early 1700s. Not only have themethods of growing rice changed dramatically in the last 300 years, but also the systemsby which we share information about rice production. Although there are other methodsof disseminating information, for years extension and research publications haveaddressed specific aspects of rice production in the state. In the 1980s several facultymembers in the Louisiana State University Agricultural Center recognized that acomprehensive, one-volume publication was needed to advise extension agents,agribusiness dealers, consultants and any other rice industry representatives about riceproduction in Louisiana. That Rice Production Handbook, published in 1987, was notintended to replace other LSU Agricultural Center publications, but to enhance existingand future rice publications written by the LSU Agricultural Center faculty.

The current volume, in many ways, is not a revision of the 1987 publication althoughsome portions of the original version have been revised. The Louisiana Rice ProductionHandbook is, in reality, a new publication encompassing the technology and knowledgeof today that will help the rice industry of Louisiana flourish in the next millennium.

I thank all of those who supported this effort, especially the authors of the varioussections and the reviewers of the entire publication. Their many hours of dedication,advice and encouragement are appreciated more than can be expressed here. Also,thank you to all who provided the slides for the photographs. Photographs express inmany ways what words cannot.

IntroductionIntroductionIntroductionIntroductionIntroductionSteven D. Linscombe

French explorers led by Bienville first introduced rice into Louisiana in 1718. Theproduction of rice was limited for the next 150 years. It was grown mainly in smallplots along the Mississippi River as food for laborers and low income farmers.Production increased rapidly after the Civil War. The total crop increased from 1.6million pounds in 1864 to 9.5 million pounds four years later. Production reached 22million pounds by 1874 and doubled in the next three years.

In 1884, a visiting farmer from Iowa discovered that rice could be produced on thebroad flat prairie lands of southwest Louisiana by using mechanized methods then usedto produce wheat in the upper Mississippi Valley. This led to a major expansion of riceproduction.

Production has expanded to other areas of Louisiana, especially the northeasternportion. Rice continues to be an important agronomic crop in southwestern Louisianaalso. Rice acreage has fluctuated in Louisiana in recent years from a high of 620,000acres in 1994 to a low of 518,000 acres in 1991. Much of this fluctuation has beencaused by farm policy programs and world market economics.

Rice will continue to be important to Louisiana agriculture. With this in mind, LSUAgricultural Center scientists who work in various aspects of rice production andeconomics in Louisiana have written this publication to help Louisiana producersincrease yields while holding down costs and thus increase their profits.

The information incorporates the latest findings from extensive rice research andextension programs conducted in Louisiana by the LSU Agricultural Center. Much of thiswork is funded at least partially by the state’s rice producers through check-off fundsadministered by the Louisiana Rice Research Board.

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General Agronomic GuidelinesGeneral Agronomic GuidelinesGeneral Agronomic GuidelinesGeneral Agronomic GuidelinesGeneral Agronomic GuidelinesSteven D. Linscombe, John K. Saichuk, K. Paul Seilhan, Patrick K. Bollich

and Eddie R. Funderburg

soils are usually not suitable for riceproduction. An important factor, regardlessof soil texture, is the presence of animpervious subsoil layer in the form of afragipan, claypan or massive clay horizonthat minimizes the percolation of irrigationwater, making it possible to hold water inrice paddies which are, in essence,shallow ponds.

Water RequirementsWater RequirementsWater RequirementsWater RequirementsWater RequirementsThe ability to achieve optimum water

management is essential in attempting tomaximize rice yields. In general, pumpingcapabilities are adequate if a field can beflushed in two to four days, flooded infour to five days, and drained, dried andreflooded in two weeks. This is mucheasier on fields that have been uniformlyleveled to a slope of no more than 0.2foot fall between levees.

Planting DatesPlanting DatesPlanting DatesPlanting DatesPlanting DatesThe optimum seeding dates will vary

by location as well as from year to yearbecause of variation in environmentalconditions. Rice yields may be reduced byplanting too early or too late. Averagedaily temperature at seeding is importantin stand establishment. At or below 50degrees F, little or no rice seedgermination occurs. From 50 degrees to55 degrees F, germination increases butnot to any great extent until above 60degrees F. Plant survival is not satisfactoryuntil the average daily temperature isabove 65 degrees F.

Based on this information and seedingdate research, the following dates ofseeding recommendations are made:

Southwest Louisiana - March 20 - April30

North Louisiana - April 10 - May 15Extremely early seeding can lead to a

number of problems including (1) slowemergence and poor growth under colderconditions because of the inherent lack ofseedling vigor and cold tolerance in manyvarieties, (2) increased damage from

Site SelectionSite SelectionSite SelectionSite SelectionSite SelectionBecause rice is grown under flooded

conditions, it is best produced on land thatis nearly level, minimizing the number ofwater retaining barriers or levees required.Some slope is required to facilitateadequate drainage. Generally, slopes ofless than 1 percent are necessary foradequate water management. Most ofLouisiana’s rice-growing areas are wellsuited for rice production with a minimumof land forming. Recent innovations usinglaser systems have made precision leveledor graded fields physically andeconomically feasible.

Precision grading of fields to a slope of0.2 foot or less change in elevationbetween levees is important in riceproduction for the following reasons: (1)permits uniform flood depth, (2) mayeliminate a large number of levees, (3)facilitates rapid irrigation and drainage, (4)can lead to the use of straight, parallellevees which will increase machineefficiency, (5) eliminates knolls andpotholes which may cause delay of floodor less than optimum weed control and (6)reduces the total amount of waternecessary for irrigation.

Previous cropping history is importantwhen selecting fields. Some herbicidesused on rotation crops may persist in thesoil and injure rice planted the next year.Some herbicide labels may precludegrowing rice the year after that herbicideis used.

SoilsSoilsSoilsSoilsSoilsRice can be grown successfully on

many different soil textures throughoutLouisiana. Most rice is grown on the siltloam soils derived from either loess or oldalluvium, which predominate thesouthwestern region, and, to a lesserextent, the Macon Ridge area of northeastLouisiana. The clay soils in thenortheastern and central areas derivedfrom more recent alluvial deposits are alsowell adapted to rice culture. Deep sandy

General Agronomic GuidelinesGeneral Agronomic GuidelinesGeneral Agronomic GuidelinesGeneral Agronomic GuidelinesGeneral Agronomic GuidelinesSteven D. Linscombe, John K. Saichuk, K. Paul Seilhan, Patrick K. Bollich

and Eddie R. Funderburg

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seedling diseases (predominantly watermold) under cool conditions, (3) increaseddamage from birds (blackbirds, ducks andgeese) which are more numerous in theearly spring and (4) decreased activity ofsome herbicides.

While later seeding may avoid someproblems associated with very earlyplanting, delays much beyond theoptimum planting dates usually result inother problems. In general, excessivelylate planting results in lower yields,increased disease and insect pressure, andpoorer grain quality at harvest.

Seeding RatesThe establishment of a satisfactory plant

population is an essential first step insuccessful rice production. Whencompared to other crops such as corn andsoybeans, the emergence rate of rice isquite low, ranging from 50 percent to 60percent. This is especially true in waterseeding and reduced tillage systems.Seeding rates have been determined byresearchers with these factors taken intoconsideration.

Rice in Louisiana is planted using threebasic methods: water seeding (dry orpresprouted seed dropped into a floodedfield), drill seeding (planting with a drillon 7- to 10-inch drill spacing) and drybroadcasting (dry seed applied to adrained or dry field by either groundequipment or airplane).

Regardless of the seeding system used,the desired plant stand is constant. Theoptimum stand is 15-20 plants per squarefoot; the minimum stand is eight plants persquare foot and the maximum stand isabout 30 plants per square foot. Like mostgrasses, rice has the ability to tiller or stooland produce several panicle-bearing stemsfrom one plant. This ability to compensateaccounts for successful grain productionfrom as few as eight seedlings per squarefoot, provided proper cultural practices areused and growing conditions are good.Stands also can be too dense. Excessiveplant populations can often lead toreduced tiller production, more severe

disease pressure and spindly plants thatmay be more susceptible to lodging.

Experimental results and commercialexperience have shown that higherseeding rates are required when broadcastseeding than drilling rice. Water seeding ordry broadcasting requires 120-150 poundsof seed per acre. Drill seeding requires90-110 pounds of seed per acre. Withineach category is a range of planting ratesto allow for some adjustment. The higherseeding rates should be used whenplanting under less than optimumconditions. Examples of circumstanceswhen the higher seeding rate should beused include:

(a) Use higher recommended seedingrates when planting early in the seasonwhen there is potential for unfavorablycool growing conditions. Cool conditionswill favor water mold (seedling disease) inwater-seeded rice. This can reduce stands.Varieties also differ in tolerance to coolgrowing conditions in the seedling stage.

(b) Varieties differ considerably inaverage seed weight. Thus, a variety witha lower average seed weight will havemore seed per pound. Table 1 shows seedweight per pound and the average numberof seed per square foot at several seedingrates for most of the varieties. Producersmay want to adjust seeding rates for thisfactor.

(c) Where seed depredation byblackbirds is potentially high, use a higherseeding rate.

(d) Where seedbed preparation isdifficult and a less than optimum seedbedis prepared, use a higher seeding rate.

(e) If it is necessary to use seed of lowgermination percentage, compensate withseeding rates. Always use highgermination, certified seed if possible.

(f) When water seeding into stale orno-till seedbeds with excessive vegetation,use higher seeding rates.

(g) If any other factor exists which maycause stand establishment problems (suchas slow flushing capability or saltwaterproblems), consider it when selecting aseeding rate.

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Dry Seeding, Fertilization Timing andWater Management

Dry seeding is the predominant methodof seeding used in the north Louisianarice-growing areas. Dry seeding normallyworks best on those soils where a well-prepared seedbed is practical and wherered rice is not a severe problem. Rice canbe dry-seeded using either a grain drill orby broadcasting.

When rice is to be drill seeded, a well-prepared, weed-free seedbed is desirable.A well-prepared seedbed will facilitateuniform seeding depth. This is importantin establishing a uniform stand. Depth ofseeding is important with all varieties, butis critical with semidwarf varieties. Thesemidwarfs are inherently slower indevelopment during the seedling stage,and the mesocotyl length is shorter than intaller varieties. Therefore, semidwarfsshould be seeded no deeper than 1 inch tomaximize uniform stand establishment.The taller varieties may be plantedsomewhat deeper, but avoid seedingdepths of more than 2 inches with anyvariety.

Where soil moisture is adequate, a flushmay not be necessary. But, when soilmoisture is insufficient and rainfall is notimminent, the field should be flushedwithin four days after seeding to assureuniform emergence. This necessitateshaving levees constructed and butted at orsoon after seeding.

Rice can be broadcast on a dry seedbedusing either ground or aerial equipment.Seed should be covered using a harrow orsimilar implement. Uniformity of seedingdepth is much more difficult using thissystem. As with drill seeding, animmediate flush may facilitate uniformstand establishment.

Fertilization timing and watermanagement are similar for both drill-seeded and broadcast dry rice.Phosphorus, potassium and micronutrientfertilizers should be preplant incorporatedbased on soil test results. The addition of15 to 20 pounds of preplant nitrogen willensure against nitrogen deficiency inseedling rice and is generally

recommended. Avoid large amounts ofpreplant nitrogen in a dry-seeded systemsince wetting and drying cycles before thepermanent flood can lead to loss of muchof this nitrogen. Most of the nitrogenshould be applied to a dry soil surfacewithin five days of permanently floodingthe field. If the precise nitrogenrequirement is known, if the permanentflood will be maintained, and if the fieldwill not be allowed to dry until maturity,all of the nitrogen can be applied ahead ofthe permanent flood.

When the required nitrogen rate is notknown, or the field will be drained beforeharvest for any reason, apply about 70percent of the estimated requirement atthis time. Additional nitrogen should beapplied at mid season. Large amounts ofnitrogen should not be applied into theflood on seedling rice because it is subjectto loss. With this system, the permanentflood should be applied as soon aspossible without submerging the riceplants. This will normally be at the 4 to 5leaf stage in fairly level fields. Delayingpermanent flood with the intention ofreducing irrigation costs may increaseother production costs, reduce yields anddecrease profits. Additional informationon fertilizer timing in relation to watermanagement can be found in the RiceSoils, Plant Nutrition and Fertilizationsection.

Water Seeding, Fertilizer Timing andWater Management

Water seeding is the predominantmethod of rice seeding used in Louisiana.It is widely used in southwest Louisianaand, to a lesser extent, in the northernportion of the state.

The use of a water seeding system canprovide an excellent cultural method ofred rice suppression and is the primaryreason for the popularity of this system insouth Louisiana. Rice farmers who raisecrawfish in rice fields use water seedingbecause it is easily adapted to thesituation. Other farmers have adoptedwater planting as a matter of custom,convenience or both. Water seeding is

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sometimes an alternative plantingoperation when excessive rainfall preventsdry planting methods.

Seedbed preparation is somewhatdifferent when water seeding is used. Theseedbed should be left in roughercondition than for dry seeding. This can beaccomplished by preparing a seedbedconsisting primarily of large clods(approximately baseball-sized). Thismethod may be easier to accomplish withheavy textured soil. Then begin floodingas soon as possible. The rice should thenbe seeded within three to four days. Thiswill reduce potential weed problems andprovide a more favorable oxygenrelationship at the soil/water interface.Low oxygen levels are often a problemwhere flood water is held for a long timebefore seeding.

A preferable alternative is to prepare asmooth seedbed similar to that for drillseeding then firm with a groovingimplement. The result is a seedbed withgrooves (1 ½ - 2 inches deep) on 7- to 10-inch centers. In some cases a fieldcultivator can do an acceptable job. Someproducers are constructing tools solely forthis purpose. They are based on similartools used in California and on Louisianaingenuity.

The rough seedbeds minimize seeddrift and facilitate seedling anchorage andrapid seedling development. Seed andseedling drift can often be quite severe,especially in large cuts which arebecoming more common as a result ofprecision leveling. The large clods orshallow grooves provide a niche for theseed to fall into and give some protectionfrom wave action.

Avoid dragging a field in the waterbefore seeding because: (1) Draggingleaves a seedbed in an extremely slickcondition, which will often lead to severeseed drift, (2) crusting and curling of thesurface after draining is normally moresevere where a field has been dragged,(3) when the drag is pulled to anexcessive depth, incorporated fertilizersand herbicides are displaced and unevenlydistributed and (4) the potential for soil

loss during the initial drain is increased bydragging.

Water planting may be accomplishedwith dry or presprouted seed. Usingpresprouted seed when water plantingoffers the advantages of higher seed weightand initiation of germination. Presprouting isaccomplished by soaking seed for 24-36hours and draining for 24-36 hours prior toseeding. Under cool conditions, theseperiods may need to be extendedsomewhat. A disadvantage is that seed mustbe planted shortly after presprouting ordeterioration will occur.

Water management of water-seeded riceafter seeding may be categorized asprolonged drainage, pinpoint flood orcontinuous flood.

Delayed FloodWhen a delayed flood system is used,

fields are drained after water seeding for anextended period (usually three to fourweeks) before the permanent flood isapplied. This system is normally usedwhere red rice is not a problem because itgives no red rice suppression. With thissystem, fertilization timing and watermanagement after the initial drainage aresimilar to dry-seeded systems.

Pinpoint FloodThe most common water seeding system

is the pinpoint flood. After seeding withpresprouted seed, the field is drainedbriefly. This drainage period is only longenough to allow the radicle to penetrate thesoil (peg down) and anchor the seedling.Under normal conditions, a three- to five-day drainage period is sufficient. The fieldis then permanently flooded until the ricenears maturity. (An exception is whenmidseason drainage is necessary to alleviatestraighthead.) Rice plants emerge throughthe flood. The plant must be above thewater surface by at least the fourth leafstage. Before this stage, the plant normallyhas sufficient stored food and availableoxygen to survive. Atmospheric oxygenand other gases are then necessary for theplant to grow and develop. This system isan excellent means of suppressing red rice

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from seeds in the soil. Since the field ismaintained in a flooded (or saturated)condition, oxygen necessary for red ricegermination is not available.

Continuous FloodA continuous flood system is used on a

limited basis in Louisiana. This system issimilar to the pinpoint system, except thatafter seeding, the field is never drained. Ofthe three water management systems,continuous flood is normally best for redrice suppression, but stand establishment ismost difficult. Even the most vigorousvariety may have problems becomingestablished under this system.

Table 1. Seed per pound and average number ofTable 1. Seed per pound and average number ofTable 1. Seed per pound and average number ofTable 1. Seed per pound and average number ofTable 1. Seed per pound and average number ofseed per square foot for important rice varieties.seed per square foot for important rice varieties.seed per square foot for important rice varieties.seed per square foot for important rice varieties.seed per square foot for important rice varieties.

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Average number of seed/ft Average number of seed/ft Average number of seed/ft Average number of seed/ft Average number of seed/ft22222 at at at at at various seeding rates various seeding rates various seeding rates various seeding rates various seeding rates

80 100 120 140Variety Seed/lb lb/A lb/A lb/A lb/A______________________________________________________________________________

Akitakomachi 17579 32 40 48 56Alan 20731 38 48 58 67Bengal 15442 28 35 42 49Cypress 19156 35 44 53 62Della 21429 39 49 59 69Dellrose 18564 34 43 52 60Dixiebelle 21919 40 50 60 70Drew 20938 38 48 58 67Gulfmont 16099 30 37 44 52Jackson 18607 34 43 52 60Jasmine-85 18088 34 42 50 59Jefferson 15133 28 35 42 49Jodon 18160 34 42 50 59Katy 21827 40 50 60 70Kaybonnet 21826 40 50 60 70Lacassine 18306 34 42 50 59Lafitte 17734 33 41 49 57LaGrue 18088 34 42 50 59Lemont 17322 32 40 48 56Litton 17597 32 40 48 56Mars 17832 33 41 49 57Maybelle 18996 35 44 53 62Millie 17004 31 39 47 55Priscilla 16449 30 38 45 52Rico 1 17024 31 39 47 55Saturn 21120 38 48 58 67Toro-2 17869 33 41 49 57

Fertilization timing is the same for boththe pinpoint and continuous flood systems.Phosphorus, potassium, sulfur and zincshould be preplant incorporated as in thedry-seeded system. Once the flood isapplied, the soil should not be allowed todry.

If the nitrogen requirement is known, allnitrogen should be incorporated preflood-preplant. Otherwise, incorporate 70 per-cent of the estimated requirement, thenapply the additional nitrogen as a topdressat midseason. More information on fertilizertiming in relation to water management isin the Soils, Plant Nutrition and Fertilizationsection.

Second CropProduction in Rice

The climaticconditions ofsouthwest Louisiana,along with theearliness ofcommonly grown ricevarieties, combine tocreate an opportunityfor second cropproduction. Secondcrop rice, also knownas stubble or ratooncrop rice, isproduced fromregrowth on thestubble after the firstcrop has beenharvested.

Weather duringthe fall will normallydictate howsuccessful a farmercan be at producing asecond crop. Mildtemperatures willspeed second cropmaturity and canprevent excessivesterility (or blanking)associated with lowtemperatures atflowering. Rememberthat average dailyhigh and lowtemperatures used in

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DD-50 based predictions are just asimportant in the development of secondcrops. Later than normal first frost dateswill help to produce second crops,especially when the first crop washarvested later than August 10. It isrecommended that the first crop beharvested at least by the middle of Augustto assure adequate time for the secondcrop to develop. In years with anabnormally mild fall and a late first frost,second crops can be produced when thefirst crop is harvested as late as the firstweek of September, but this is theexception rather than the rule.

While cooperation from the weather isessential for second crop production,cultural practices can play an extremelycritical part in maximizing stubble cropyields. It must be emphasized that culturalpractices used in the first crop can have amajor impact on second crop production.Excessive rates of nitrogen applied to thefirst crop can often delay the regrowth ofthe second crop. Therefore, excessiverates of nitrogen should be avoided evenwith a variety with high levels ofresistance to lodging. Disease pressure inthe first crop can have an effect on thesecond crop. Severe disease pressure inthe first crop can actually cause death oftillers and prevent regrowth from theseplants. Use of a foliar fungicide in the firstcrop can be beneficial to the second crop.

Conditions at harvest will influencewhether a second crop should beattempted. If it’s necessary to harvestunder muddy conditions and the field isexcessively rutted, second cropping willbe difficult and probably should not beattempted. Excessive amounts of red ricein the first crop will also limit yield andreduce quality in the second. It may bebeneficial to avoid second crop productionand concentrate on encouraginggermination of red rice seed followed bydestroying the seedlings by fall plowing.This may decrease the red rice problem insucceeding crops.

An application of nitrogen fertilizer willbe necessary when striving for highsecond crop yields. It is normally best to

apply the nitrogen to a dry soil surfaceand establish a shallow flood immediatelyafter harvest. This will facilitate rapidregrowth and efficient use of appliednitrogen.

Consult the annual publication RiceVarieties and Management Tips (Publication2270) when selecting varieties with theintention of producing ratoon or secondcrop rice.

Conservation Tillage ManagementThe following information is based in

part on specific research results obtainedfrom studies conducted at the RiceResearch Station since 1987. Some hasbeen generalized based on observationsfrom these studies and not necessarilyscientific measurements. The knowledgebase on conservation tillage in rice is stilllimited, and additional research needs tobe conducted. Basic components of thesealternative production practices will besummarized emphasizing advantages anddisadvantages. This information isadequate for use as a general guidelinebut may not be applicable to everysituation. Three alternative seedbeds havebeen compared with conventionallyprepared seedbeds in both water- anddrill-seeded cultural systems. The practicesare defined as follows:

Spring Stale SeedbedLand is prepared three to six weeks

before planting. Depending ontemperature and rainfall, vegetation thatestablishes before planting is usually small,sparse and easy to control. Most farmerssee little advantage to this option whencompared with spring seedbed preparationat the normal time. But, this option doesoffer one important benefit. During drysprings, seedbeds can be worked earlyand readied for planting. If excessiverainfall occurs before planting, time,money and labor can be saved bycontrolling preplant vegetation with aburndown herbicide rather than waiting forthe seedbed to dry enough to preparemechanically. This system improves thechance of timely planting.

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Fall Stale SeedbedSeedbeds are completely prepared in

the fall. Vegetation that establishes overthe winter in this practice is usuallyuniform in cover, 8 to 10 inches in height,and consists of winter annual grasses,clovers, vetches and other broadleaves.This practice is probably the most popularin the southwest area. Better dryingconditions and more favorable weather inthe fall allow more opportunity for fieldpreparation.

No-tillRice is planted directly into previous

crop residue or native vegetation. In thesouthwest area, soybeans would be thetypical rotation crop. Cotton and soybeansare options in northeast Louisiana. Preplantvegetation is usually not uniform in sizeand is usually comprised of much larger,woody winter weeds that pose problemswhen controlling preplant vegetation. Riceestablishment practices used inconservation tillage systems are describedbelow.

Preplant vegetation control -Roundup and Gramoxone are labeled forburndown in rice. Consult the herbicidelabel for rate of application and weedcontrol spectrum. Rate depends on typeand size of weed, and herbicides shouldbe applied according to label directions.Some rice is no-tilled without terminationof preplant vegetation. This is possible ifweed growth is minimal and thevegetation is winter annuals that willeventually die out or be killed by flooding.Significant yield reductions have occurredin studies where preplant vegetation wasexcessive and a herbicide was not usedfor burndown. Opting not to use aburndown chemical can be risky, andweed identification is extremely important.

Time of application in relation toplanting - Best results in most of theresearch have occurred with a seven- to10-day preplant application. This isespecially true when the residualherbicides are tankmixed with theburndown herbicides. Longer intervalsbetween burndown and planting reducethe effectiveness of residual weed control

in the planted rice crop. There are alsopreplant intervals for Harmony Extra (45-day) and 2,4-D (15-day) applied alone ortankmixed with burndown herbicides. Adisadvantage is the extended preplant timeintervals, especially with Harmony Extra.All of these herbicides must be appliedaccording to label directions.

Planting practices - Use presproutedseed when water seeding. This will helpestablish stand more rapidly and minimizegermination problems associated with poorfloodwater quality, low oxygen, seedlingdiseases and potential seed midgedamage. Seed-to-soil contact is importantand is a function of the amount ofvegetation and, to some extent, the typeof vegetation. When drill seeding, it isimportant to use planting equipment thatplaces seed at a uniform depth and closesthe seed slit to conserve moisture. Onsome soils, it may not be necessary to useno-till equipment.

Good quality conventional plantersperform well on mellow seedbeds. Heavy,no-till equipment is desirable wherevegetation is excessive and seedbeds arecompacted.

Water management - Reduced standhas been a common problem in water-seeded, no-till rice, especially whenpinpoint flooding. Delaying permanentflood establishment for two to three weeksafter water seeding and draining willimprove stands in some situations. It isimportant, however, that adequatemoisture be provided by rainfall orirrigation in delayed flood systems.Excessive drying of the seedbed duringrooting can also cause stand reduction.Delayed flooding is not a desirablemanagement practice when red rice is aproblem, and control or suppression of redrice will be significantly reduced whenthis type of water management ispracticed. Red rice control usingconservation tillage has been lessconsistent than conventional water seedingpractices.

Stand establishment difficultiesencountered when drill seeding have oftenbeen associated with lack of moisture. Ifmoisture is inadequate at planting, flush

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the field to encourage uniform emergenceand stand establishment. Gibberellic acidseed treatment may also enhanceemergence of some varieties. In water-seeded systems, seed to soil contact isoften poor. As a consequence, frequentflushing in delayed flood systems may berequired. In a pinpoint flood system, itmay be necessary to drain more than onceto encourage rooting.

Variety selection - Variety selection ina no-till system is important. Goodseedling vigor, tillering ability and yieldpotential are important characteristics.Under ideal conditions, any commercialvariety being grown could be considered.Research supports the fact that no-till andstale seedbeds are not ideal situations, andvarieties that possess all of the abovecharacteristics have shown the mostconsistency. Some semidwarf varieties,such as Lemont, struggle to establish standin no-till seedbeds, especially when waterseeded. Yields have generally beenreduced. Varieties that are taller or possessgood seedling vigor have performed well.

Cypress is a semidwarf but hasexcellent seedling vigor and has shownconsistency and good yielding ability. Tallvarieties, such as Mars and Jackson, arealso good candidates. Maybelle has beensomewhat inconsistent. Any of thesevarieties has potential in a no-till systemunder ideal conditions; however, there ismerit to choosing one over another basedon the above general criteria.

Fertilizer management - Plantnutrients can be surface applied in a no-tillsystem. In stale seedbeds, phosphorus (P)and potassium (K) can be incorporated atthe time of land preparation. This isbecoming a popular practice with fallprepared seedbeds. Nitrogen managementin the spring rice crop is much easierwhen P and K have already been applied.In areas where scumming may be aproblem, P and K should be applied in ano-till system after rice stand has beenestablished but by the fifth leaf stage.These nutrients can be applied intostanding floodwater or before permanentlyflooding.

When not to no-till - Excessivevegetation, hard to control weeds, ruttedfields, unlevel land and red rice problemfields are all candidates to consider formore conventional planting practices.Heavy vegetation reduces seed-to-soilcontact and increases problemsestablishing adequate stand. Weeds notcontrolled before planting will causesignificant problems with expensivesolutions after planting. Rutted fields andunlevel land affect both flooding anddraining of rice fields. Water managementproblems can be detrimental to successfulrice production. Control of red rice in no-till fields is still being evaluated. Severelyinfested fields should be managed bymore conventional means.

Growth and Development of the Rice PlantGrowth and Development of the Rice PlantGrowth and Development of the Rice PlantGrowth and Development of the Rice PlantGrowth and Development of the Rice PlantRichard T. Dunand

IntroductionGrowth and development of the rice

plant involve continuous change. Thismeans important growth events areoccurring in the rice plant at all times.Therefore, the overall daily health of therice plant is important. If the plant isunhealthy during any state of growth, theoverall growth, development and grainyield of the plant are limited. It isimportant to understand the growth anddevelopment of the plant.

The changes that occur in the rice plantas it grows and develops occur inside aswell as outside and underground as wellas above ground. These changes can begrouped into two phases of growth, eachof which has several identifiable growthstages based on development of the shoot.

The ability to identify growth stages isimportant for proper management of therice crop. As more becomes known aboutfactors affecting rice growth and

Growth and Development of the Rice PlantGrowth and Development of the Rice PlantGrowth and Development of the Rice PlantGrowth and Development of the Rice PlantGrowth and Development of the Rice PlantRichard T. Dunand

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development, management practicesdesigned to increase rice production willemerge. These management practices, justas some of those in present use, will betied to the growth and development of therice plant. An understanding of the growthof rice is essential for management of ahealthy crop and for the proper use of theDD-50 rice management program.

Phases of GrowthThe growth and development of rice

begin with the germination of the seedand end with the formation of grain.During that period, the growth anddevelopment of the rice plant can bedivided into two phases: vegetative andreproductive. These two phases deal withthe growth and development of differentplant parts, and they overlap.

The vegetative phase deals primarilywith the growth and development of theplant from germination to the beginning ofpanicle development inside the main stem.The reproductive phase deals mainly withthe growth and development of the plantfrom the end of the vegetative phase tograin maturity. Both phases are importantin the life of the rice plant. Theycomplement each other to produce a plantwhich can absorb sunlight and convert thatenergy into food in the form of grain.

The vegetative and reproductivephases of growth are subdivided intogroups of growth stages. In the vegetativephase of growth, there are four groups: (1)emergence stages (2) seedling stages (3)tillering stages and (4) internode formationstages. Similarly, the reproductive phaseof growth is subdivided into five groups:(1) prebooting stages (2) booting stages (3)heading stages (4) grain filling stages and(5) maturity stages. These growth stagesare easily identified.

Growth Stages in the Vegetative Phase

Emergence StagesThere are two emergence stages,

germination and emergence. Germinationis the first event in the life of a rice plant.When exposed to the proper conditions,the seed swells as moisture is absorbed.

Imbibition of water activates the embryo,and the endosperm can serve as a sourceof nutrients for the growing embryo forabout three weeks. In the embryo, twoprimary structures grow and elongate: theradicle (first root) and coleoptile(protective covering enveloping the firstleaf). As the radicle and coleoptile grow,they apply pressure to the inside of thehull. Eventually the hull weakens underthe pressure, and the pointed, slenderradicle and coleoptile emerge. When theradicle and coleoptile emerge from thehull, the stage of growth of the plant isgermination (Fig. 1).

After germination, the radicle andcoleoptile continue to grow and developprimarily by elongation (or lengthening)(Fig 2). The coleoptile elongates until itencounters light. To help the coleoptile toreach light, sometimes a second elongatingstructure, the mesocotyl, develops (Fig. 3).The mesocotyl originates from the embryoarea and is attached to the base of thecoleoptile. The mesocotyl and coleoptilecan elongate at the same time. They aresometimes difficult to tell apart. Usuallythe mesocotyl is white, and the coleoptileis off-white, slightly yellowish. Shortlyafter the coleoptile is exposed to light,usually at the soil surface, it stopselongation. At this time the stage ofgrowth of the plant is emergence.

Seedling StagesThe seedling stages of growth begin

when the primary leaf appears shortlyafter the coleoptile is exposed to light andsplits open at the end (Fig. 4). Theprimary leaf elongates through and abovethe coleoptile (Fig. 5). It has no typicalleaf blade and is usually an inch or less inlength. The primary leaf acts as aprotective covering for the nextdeveloping leaf. As the seedling grows,the next leaf elongates through and pastthe tip of the primary leaf. Continuing togrow and develop, the leaf differentiatesinto three distinct parts: the sheath, collarand blade (Fig. 6). A leaf that isdifferentiated into a sheath, a collar and ablade is complete; thus the first leaf todevelop after primary leaf is the first

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complete leaf. This stage of growth is firstleaf (Fig. 7).

All subsequent leaves after first leaf arecomplete leaves. The sheath is normallythe bottom-most part of a complete leafand is an elongated structure which growsupright and surrounds the stem. During theseedling stages, leaf sheaths originate atthe base of the stem. In rice, the collar is asmall area at the top of a leaf sheath and isthe point of origin of the blade. Thesheath and collar are the most rigidportions of the leaf. The blade is flexible.The blade angles away from the sheathand is flat with a pronounced, rigid midribon its underside. The midrib runs thelength of the blade and provides supportfor the blade.

The blade is the part of the leaf wheremost photosynthesis occurs. It containsmore chlorophyll than any other part ofthe leaf. Chlorophyll is the compound inleaves which absorbs sunlight and convertsit to energy for growth. Chlorophyll isgreen, causing the blade to be thegreenest part of the plant. The blade is thefirst part of a complete leaf to appear as aleaf grows and develops. It is thenfollowed in order by the appearance ofthe collar at the base of the blade and thenthe sheath below the collar. During thevegetative phase of growth, only the collarand blade of each complete leaf becomefully visible. Only the upper portion of thesheath is visible, since the sheath remainscovered in part by sheaths of leaveswhose development preceded it.

Since growth and development arecontinuous, at first leaf the tip of the bladeof the second complete leaf usually isalready protruding through the top of thesheath of the first complete leaf. Thesecond complete leaf grows and developsin the same manner as the first completeleaf, and when the collar is visible abovethe collar of the first complete leaf, thestage of growth is second leaf (Fig. 8).Subsequent leaves develop in the samemanner, and the stages of growth areclassified accordingly as third leaf, etc.

When the second complete leafmatures, the sheath and blade are eachlonger and wider than their counterparts

on the first complete leaf. This trend isnoted for each subsequent leaf until aboutthe ninth complete leaf, after which leafsize decreases. Although a rice plant canproduce many leaves, as new leaves areproduced, older leaves senesce, resultingin a somewhat constant four to five leavesper plant at any given time. The secondcomplete leaf develops on the side of theculm from the first complete leaf.Subsequent leaves develop in thisalternate fashion so the third completeleaf is higher on the stem than the secondcomplete leaf and develops on the sameside of the stem as the first leaf, producinga pattern referred to as two-ranked and ina single plane. Seedling growth continuesin this manner through third to fourth leaf,clearly denoting plant establishment.

The root system begins to developmore fully during the seedling stages. Inaddition to the radicle, other fibrous rootsdevelop from the seed area and, with theradicle, form the primary root system. Theprimary root system grows into a shallow,highly branched mass limited in its growthto the immediate environment of the seed.The primary root system is temporary,serving mainly to provide nutrients andmoisture to the emerging plant and youngseedling. In contrast, the secondary rootsystem originates from the base of thecoleoptile. During the seedling stages, thesecondary root system is not highlydeveloped and appears primarily asseveral nonbranched roots spreading in alldirections from the base of the coleoptilein a plane roughly parallel to the soilsurface. The secondary root system ismore permanent. It provides the bulk ofthe water and nutrient requirements of theplant after the seedling stages.

During the seedling stages, the planthas clearly defined shoot and root parts(Fig. 9). Above the soil surface, the shootis composed of one or more completelydeveloped leaves at the base of which arethe primary leaf and upper portions of thecoleoptile. Below the soil surface, the rootsystem is composed of the primary rootsystem originating from the seed and thesecondary root system originating from thebase of the coleoptile. Plants originating

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from seed placed deep below the soilsurface will have extensive mesocotyl andcoleoptile elongation compared to plantsoriginating from seed placed near the soilsurface. Seed placement on the soil surfaceusually results in no mesocotyldevelopment and little coleoptileelongation. In general, the presence ofprimary and secondary roots and a shootwhich consists of leaf parts from severalleaves is the basic structure of the riceplant during the seedling stages of growth.

Tiller StagesTillers (stools) first appear as the tips of

leaf blades emerging from the tops ofsheaths of completely developed leaves onthe main shoot. This gives the appearanceof a complete leaf that is producing morethan one blade. This occurs because tillersoriginate inside the sheath of a leaf justabove the point where the sheath attachesat the base of the plant. If the leaf sheathis removed, the bud of a beginning tillerwill appear as a small green triangulargrowth at the base of the leaf. Tillerswhich originate on the main shoot in thismanner are primary tillers. When the firstcomplete leaf of the first primary tiller isvisually fully differentiated (blade, collarand sheath apparent), the stage of growthof the plant is first primary tiller (Fig. 10).

The first primary tiller usually emergesfrom the sheath of the first complete leafbefore fifth leaf. If a second tiller appears,it usually emerges from the sheath of thesecond complete leaf and so on.Consequently, tillers develop on the mainshoot in an alternate fashion like theleaves. When the second primary tillerappears, the stage of growth of the plant issecond primary tiller (Fig. 11). Theappearance of tillers in this manner usuallycontinues through about fourth or fifthprimary tiller. If plant populations are verylow (fewer than 10 plants per square foot),tillers may originate from primary tillersmuch in the same manner as primary tillersoriginate from the main shoot. Tillersoriginating from primary tillers aresecondary tillers, and, when this occurs,the stage of growth of the plant issecondary tillering.

Tillers grow and develop in much thesame manner as the main shoot, but theylag behind the main shoot in theirdevelopment. This lag is directly related tothe time a tiller first appears. It usuallyresults in tillers producing fewer leavesand having less height and slightly latermaturities than the main shoot.

During the tillering (stooling) stages, atthe base of the main shoot, crowndevelopment becomes noticeable. Thecrown is the region of a plant where ashoot and secondary roots join. Inside acrown, nodes form at the same time as thedevelopment of each leaf. The nodesappear as white bands about 1/16 inchthick and running across the crown, usuallyparallel with the soil surface. With time thenodes become separate and distinct, withspaces (internodes) about 1/4 inch or lessin length between them (Fig. 12). Initiallythe plant tissue between nodes is solid, butwith age the tissue disintegrates, leaving ahollow stem between nodes.

In addition to crown development, leafand root development continue on themain shoot. An additional five to sixcomplete leaves form with as manyadditional nodes forming above the oldernodes in the main shoot crown. On themain shoot, some of the older leaves turnyellow and brown. The changes in colorbegin at the tip of a leaf blade andgradually move to the base. From this pointon, there is continuous aging of olderleaves and production of new leaves. Theresult is that there are never more thanfour or five functioning leaves on a shootat one time.

In addition to changes in leaves, themain shoot crown area expands. Some ofthe older internodes at the base of thecrown crowd together and becomeindiscernible by the unaided eye. Usuallyno more than seven or eight crowninternodes are clearly observable in adissected crown. Sometimes the uppermostinternode in a crown elongates ½ - 1 inch.This can occur if depth of planting, depthof flood, plant population, nitrogen fertilityand other factors which tend to promoteelongation in rice are excessive. Alsoduring the tiller stages, tiller crowns

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develop. Along with growth of the mainshoot and tiller shoot crowns, moresecondary roots form, arising from theexpanding surface of the crowns. Theseroots grow larger than those which formedduring the seedling stages. They are widerand longer at maturity. As the tiller stagesend, the rice plant has actively tillered andhas some dead and yellowing leaves, acompletely developed main stem crown,developing tiller crowns and an activelydeveloping secondary root system.

Internode Formation StagesThe formation of internodes (joints)

above a crown is the process that producesa stem and determines stem length.Internode formation above a crown beginswith the formation of a stem node similarto that of the crown nodes. The stem nodeforms above the uppermost crown node,and a stem internode begins to formbetween the two nodes. As the steminternode begins to form, chlorophyllaccumulates in the tissue below the stemnode. This produces green color in thattissue. If the stem is properly dissected atthis time, green color encircling the stem(the green ring) may be apparent. This canbe common for all internodes formedabove the crown. When the stem node andthe uppermost node of the crown of themain shoot are clearly separated, internodeelongation has begun and the stage ofgrowth of the plant is first internode orgreen ring (Fig. 13).

Before the first internode above thecrown completes elongation, a secondstem node forms above it. A secondinternode then begins to form below thesecond stem node and develops in amanner similar to that of the first internode(Fig. 14). This sequence recurs until thelast internode elongates completely. As thenewly formed nodes on the main stembecome clearly separated by internodes,the stages of growth of the plant progressfrom first internode to second to third, etc.With the formation and elongation of eachstem internode, the length of the stem andthe height of the plant increase.

Internode elongation occurs in all stems.The main stem is usually the first to form

an internode, and it is also the first stem inwhich internode formation ends. In thetillers, internode formation lags behind themain stem and usually begins in the oldertillers first.

During the internode formation stages,each newly formed internode on a stem islonger and slenderer than the precedingone. The first internode formed is the basalmost internode. It is the shortest andthickest internode of a stem. The basalinternode is located directly above thecrown. Sometimes, if the uppermost crowninternode is elongated, it can be confusedwith the first internode of the main stem.

One difference between these twointernodes is the presence of roots.Sometimes, especially late in thedevelopment of the plant, the node at thetop of the uppermost crown internode willhave secondary roots associated with it.The upper node of the first stem internodewill usually have no roots. If roots arepresent, they will be short and fibrous. Thelast or uppermost internode which forms isthe longest and slenderest internode and isdirectly connected to the base of thepanicle. The elongation of the uppermostinternodes causes the panicle to be thrustout in the heading stages during thereproductive phase of growth.

Internode length varies, depending onvariety and management practices. Ingeneral, internode lengths vary from 1 inch(basal internode) to 10 (uppermostinternode) inches in semidwarf varietiesand from 2 inches to 15 inches in tallvarieties. These values, as well asinternode elongation in general, can beinfluenced by planting date, plantpopulation, soil fertility, depth of flood,weed competition, etc.

The number of internodes which formsin the main stem is relatively constant for avariety. Varieties now being grown havefive to six internodes form above thecrown in the main stem. In tillers, fewerinternodes form than in the main stem. Thenumber is highly variable and depends onhow much the tiller lags behind the mainstem in growth and development.

The time between seeding andinternode formation depends primarily on

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the maturity of the variety, which isnormally controlled by heat unit exposure(see DD-50 Rice Management Programsection). It can also be influenced byplanting date, plant population, soilfertility, flood depth and weedcompetition. In general, varieties classifiedas very early season maturity reach firstinternode six weeks after emergence.Varieties classified as early season maturityreach first internode seven weeks afteremergence, and varieties classified asmidseason maturity reach first internodeeight weeks after emergence.

The appearance of nodes above thecrown marks a change in the role of thenode as the point of origin of several plantparts. Before internode formation beginsabove the crown, all leaves, tillers andsecondary roots formed during that timeoriginate from crown nodes. But afterinternode formation begins above thecrown, the nodes serve mainly as thepoint of origin of all subsequent leaves.

Although possible, significant formationof tillers and roots from nodes above thecrown is rare. Since the nodes becomeseparated significantly by internodes, theleaves which originate at these nodes aremore separate and distinct than leavesformed before internode formation. Theseparation of these leaves increases as thelength of the internodes increases.Eventually, more complete leaf structurebecomes apparent until the last two leavesto form have all or most of all three parts(sheath, collar and blade) completelyvisible. Since the last leaves formedoriginate primarily from nodes above thecrown, this means that, in varieties now inuse, no more than six new completeleaves are produced on the main shootafter stem internode formation begins. Thelast of these leaves to form is the flag leaf.It is the uppermost leaf on a mature shoot,and the sheath of the flag leaf encloses thepanicle during the elongation of the lasttwo internodes.

Root growth approaches a maximum asinternode formation above the crownbegins. At this time, the secondary rootsystem has developed extensively in alldirections below the crown and has

become highly branched. Newly formedroots are white; older roots are brown andblack. A matted root system forms inaddition to the secondary root system. It iscomposed of fibrous roots, whichinterweave and form a mat of roots nearthe soil surface. In general, the rootsystem has developed horizontally to agreater degree than vertically.

Tiller formation usually ceases and tillersenescence (die off) begins during theinternode formation stages. More tillers areproduced during the tiller stages than willsurvive to maturity. In those tillers whichwill not survive, tiller senescence beginsas the crown becomes fully differentiatedand continues until the last internode formsabove the crown. A tiller which does notsurvive until maturity begins to lag behindin its development. Tiller senescence canbe recognized by the smaller size of atiller in comparison to other tillers on aplant. It appears significantly shorter thanother tillers, has fewer complete leavesand fails to have significant internodedevelopment above the crown of the tiller.Eventually most leaves on an aging tillerlose coloration while most leaves on othertillers are still green. Finally, the leavesand stems of senescing tillers turn brownand gray and, in most instances, disappearbefore the plant reaches maturity.

The internode formation stages signalthe end of the vegetative stages of growthas markers for determining the stage ofgrowth of the plant. As stem internodesbegin to form, the reproductive phase ofgrowth is beginning.

Growth Stages During theReproductive Phase

Prebooting StagesThe prebooting stages of growth are

the only stages during the reproductivephase that occur before leaf formationceases. During the prebooting stages, theremaining leaves of the plant develop,internode elongation and stem formationcontinue, and panicle formation begins.

The prebooting stages are identified bythe development of the panicle inside themain stem before the appearance of the

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sheath (boot) of the flag leaf, the last leafproduced. The prebooting stages followinternode formation and, like internodeformation, involve the movement of thegrowing point inside the main stem awayfrom the crown. Within the growing pointis a specialized group of cells whichbecomes active during the prebootingstages. The specialized group of cellsbegins actively dividing and differentiatesinto a small panicle.

When the cells first begin activelydividing in the main stem, the stage ofgrowth of the plant is panicle initiation(PI). Panicle initiation occurs during thefifth week before heading. Althoughpanicle initiation can be positivelyidentified only by microscopictechniques, it is closely associated withthe vegetative phase of growth. Thegrowth stages that coincide closely withpanicle initiation differ, depending on thematurity of a variety. In very early seasonvarieties, panicle initiation and firstinternode (green ring) occur at about thesame time. In early season varieties,panicle initiation and second internodeoccur almost simultaneously, and, inmidseason varieties, panicle initiation andthird internode are closely concurrent.

The specialized group of cells that firstbegins actively dividing at panicleinitiation continues to divide actively.Eventually, a small panicle about 1/8 inchin length and 1/16 inch in diameterforms. At this point, the panicle can beseen inside the stem, looking like a smalltuft of fuzz. When this occurs in the mainstem, the stage of growth is panicledifferentiation (PD) or panicle 2-mm (Fig.15). The panicle, although small, hasalready begun to differentiate into distinctparts. Under a microscope, thebeginnings of panicle branches andflorets are recognizable. The paniclecontinues to grow during the prebootingstages. When the panicle is 1 inch long,the stage of growth is 1-inch panicle. Atthis stage, the panicle is a very compact,elongated, slender structure covered withmany small knobs. As it grows, theknobby structures differentiate into

panicle branches which branch off themain trunk of the panicle (panicle axis)and bear the florets. During theprebooting stages of growth, the paniclebranches and florets first become visibleat the tip of the panicle. With time,panicle branches and florets appearbelow the tip.

While these developmental changesare occurring, the panicle continues toelongate. As the panicle grows anddevelops in this manner and reaches 2inches, the stage of growth is 2-inchpanicle. The identification of theprebooting stages of growth continues inthis manner in 1-inch increments until theflag leaf has differentiated on the mainstem. At that time the panicle inside themain stem has elongated about 4 inches.The florets at the tip of the panicle areclearly differentiated, while those nearthe bottom are still in the developmentalstages.

Booting StagesThe booting stages include a period

during which the preflowering growthand development of a panicle and itsconstituent parts are completed inside thesheath of the flag leaf. The sheath of theflag leaf is the boot, and the bootingstages are classified according to itsdevelopment. Booting is divided intothree stages: early, middle and late. Earlyboot (Fig. 16) occurs when the sheath ofthe flag leaf first appears above the collarof the penultimate leaf (leaf below theflag leaf) on the main stem and lasts untilthe sheath of the flag leaf is about 2inches out of the sheath. Middle bootoccurs when the sheath of the flag leaf is2 to 5 inches out of the sheath, and lateboot (Fig. 17) when the sheath of the flagleaf is 5 or more inches out of the sheathof the penultimate leaf.

During the booting stages, the growthand development of the panicle result ina fully elongated panicle with a completecomplement of panicle branches bearingmature florets. In the florets, theproduction of mature pollen begins withthe formation of pollen mother cells. This

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begins in the uppermost florets on apanicle and progresses down the panicle.The production of mature pollen reachesa maximum during early boot.

Of the panicle parts which becomeapparent during the booting stages, thepanicle branches and florets are the mostdistinct and contribute greatly to theincrease in panicle size. This is apparentin the outward appearance of a stem. Asthe panicle branches and the florets growand develop during the booting stages,the sheath of the penultimate leaf and theflag leaf swell. This creates a noticeablebulge in the upper portion of a stem. Asthe booting stages end, the panicle insidethe boot has grown to its final length andis fully differentiated into a main axiswith panicle branches bearing fullydeveloped florets. Also leaf developmenthas been completed and only the twointernodes directly below the panicleremain to elongate significantly.

Heading StagesThe heading stages are associated with

the emergence of the panicle through thesheath of the flag leaf on the main stem.(The heading stages are critical for timingof foliar fungicides; see the DiseaseManagement section for more detail.) Thisprocess is brought about mainly by thegradual and continuous elongation of theuppermost internodes. As the elongationof the uppermost internodes of the mainstem pushes the panicle out of the sheathof the flag leaf and the tip of the paniclebecomes visible, the stage is first heading(Fig. 18). The uppermost internodescontinue to elongate after first heading,revealing more of the panicle above thesheath of the flag leaf. After theuppermost internode completeselongation, the full length of the panicleand a portion of the uppermost internodeare exposed above the collar of the flagleaf. When this has occurred on the mainstem, the stage is full heading (Fig. 19).

During the heading stages, pollinationbegins (Fig. 19). Pollination is the processin which pollen is released, leading tofertilization and grain development. It is

identified by the appearance of small,usually white or yellow anthers externalto the florets. Sometimes pollinationbegins shortly after first heading, andsometimes it begins after full heading.Most of the time, the first florets toemerge are the first florets in whichpollination occurs. Pollination thencontinues down the panicle. The paniclein most varieties is green, erect andrelatively compact.

Grain Filling StagesDuring the grain filling stages, the

florets on the main stem change toimmature grains of rice. The formation ofgrain results mainly from theaccumulation of carbohydrate in theflorets. The source of the carbohydrate isthe uppermost three to four leaves andthe stem. The carbohydrate whichaccumulates in the florets is stored in theform of starch, and the starchy portion ofthe grain is the endosperm. Thecarbohydrate which is translocated fromthe leaves and stem is white and milky inconsistency as it initially accumulates. Thefirst florets which have this accumulationare the first florets pollinated. When thismilky accumulation is first noticeableinside florets on the main stem, the stageis milk stage (Fig. 20).

During milk stage, the accumulation ofcarbohydrate increases floret weight.Since the florets which accumulatecarbohydrate first are located near the tipof the panicle, the panicle begins to leanand eventually will turn down. After thefirst florets which pollinated fill, thecarbohydrate begins to solidify. When thetexture of the carbohydrate of the firstflorets pollinated on the main stem is likebread dough or firmer, the stage ofgrowth is dough stage (Fig. 21). As thecarbohydrate in these florets continues tosolidify during the dough stage, theendosperm becomes firm and has achalky texture (Fig. 22).

During the grain filling stages, theflorets develop and mature unevenlybecause pollination and subsequentlygrain filling occur unevenly. In the dough

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stage, only the florets on the main stemwhich pollinated first have an endospermwith the texture of bread dough. At thesame time, the florets which pollinatedlater, including those on the tillers, haveendosperms less mature. These are thelast florets to accumulate carbohydrate.As more and more florets fill withcarbohydrate during dough stage, thetranslocation of carbohydrate to thepanicle starts to decline, and the finalphases of grain filling occur.

The panicle changes in color and formas the florets develop and mature. Formost varieties of rice, the paniclechanges from a uniform light green atmilk stage to a mixture of shades ofbrown and green during dough stage. Asthe color changes, the shape changesalso because of the accumulation ofcarbohydrate in the florets. The weight ofthe carbohydrate causes the panicle tobend over and the panicle branches to beless compact around the panicle axis. Atthe end of the grain filling stages, thepanicle on the main culm has a bent andslightly open shape and is various shadesof brown and green. The bent andslightly open configuration of the panicleremains unchanged from dough stage tomaturity.

Maturity StagesThe maturity stages occur when

carbohydrate is no longer translocated tothe panicle. The moisture content of thegrain is high after grain filling, and theprimary process which occurs in thepanicle during the maturity stages is theloss of moisture from the grain. Themoisture content of the grain is easilydetermined. It is used as the basis for thematurity stages of growth. When thephysiological processes associated withgrain filling cease, and the collectivemoisture content of the grain on the mainstem is 25 percent to 30 percent, theplant has reached physiological maturity.

At this time, the endosperm of allgrains on the panicle of a main stem isfirm. Most grains are some shade ofbrown, and the grains in the lowerquarter of the panicle are the only oneswith a greenish tint. As the maturitystages of growth progress and moistureloss continues, the greenish tint fades andthe endosperm of all grains becomesuniformly hard and translucent. When thisoccurs, and the average moisture contentof the grains on the main stem is 15percent to 18 percent (crop grainmoisture, 18 percent to 21 percent), thestage of growth of the plant is harvestmaturity (Fig. 23).

DD-50 Rice Management ProgramDD-50 Rice Management ProgramDD-50 Rice Management ProgramDD-50 Rice Management ProgramDD-50 Rice Management ProgramJohn K. Saichuk, Steven D. Linscombe and Patrick K. Bollich

The Louisiana DD-50 Rice ManagementProgram helps rice producers manage theircrops better. Many cultural practicesdepend on specific stages in the growthand development of the rice plant. Theterm DD-50 is derived from degree-day50, a term referring to a temperature-timevalue called a heat unit. Because virtuallyall growth and development processes inrice stop at temperatures at or below 50degrees F, the term DD-50 is used. Noheat units accumulate at temperaturesbelow 50 F, but no negative values areused in the calculations. It is calculated byaveraging the maximum daily high and

low temperatures in degrees Fahrenheitand subtracting 50.

For example, if the high temperaturefor a given day is 85 degrees and the lowis 60 degrees, then the averagetemperature (72.5) minus 50 equals 12.5heat units or DD-50 units for that day.Threshold values of accumulated heat unitsfor various growth stages of rice havebeen established through research. Byadding the heat units from a given stage ofgrowth (emergence is the best), futuregrowth stages can be predicted.

Weather information is obtained fromlocations around the state and compiled by

DD-50 Rice Management ProgramDD-50 Rice Management ProgramDD-50 Rice Management ProgramDD-50 Rice Management ProgramDD-50 Rice Management ProgramJohn K. Saichuk, Steven D. Linscombe and Patrick K. Bollich

2121212121

computer. Knowing the date of emergenceon a field of a particular variety of rice ina particular area of the state enables theprogram to provide a producer withpredictions on when plants in that field willreach certain growth stages. The initialprediction is based on averagetemperatures and their corresponding heatunits in the area over the previous years.Updated predictions are provided as oftenas needed to compensate for specificconditions in a particular growing season.

The program, provided to Louisianaproducers by the LSU Agricultural Center, iscoordinated by the county agent in eachrice-producing parish. To participate, aproducer may fill out a DD-50 card (Fig.24) for each field or contact a county agent.Accuracy is essential, especially indetermining date of emergence. If thisinformation is incorrect, correspondingpredictions will be wrong.

The date of emergence depends on theseeding system. If rice is water-seeded(using prolonged drainage, pinpointflooding or continuous flooding watermanagement), the date of emergence iswhen the seedlings (shoot) are about 1/2 to3/4 inches long. With dry-seeded rice(whether drilled or broadcast), the date ofemergence is when an average of 10seedlings are visible (just breaking the soilsurface) per square foot. As soon as this

date is reached for a particular field, returnthe completed DD-50 card to the countyagent’s office.

A printout (Fig. 25) will then beprovided showing growth stage predictionsand recommended cultural practices basedon these growth stages. Again, updatedpredictions are provided when necessary.

Remember these are just predictions.Fields must still be monitored closely todetermine precise stages of development.With the aid of these predictions, criticalgrowth stages can be forecast. The fieldshould be monitored for a particular growthstage about four to five days prior to thepredicted date for its occurrence to avoidmissing the stage in the event of errors.

Anything which stresses a field of ricewill interfere with the accuracy of thesepredictions. Stresses may include insectpressure, delay of permanent flood, lack ofnutrients, disease pressure or many otherfactors. For maximum yields, avoid thesestress factors.

The varieties available with this programwill change from year to year as newvarieties are released and older varietiesare deleted from recommended lists. Apersonal computer version of the DD-50program is also available. More informationis available from Louisiana CooperativeExtension Service agents.

LOUISIANA DD - 50RICE GROWTH STAGE PREDICTION PROGRAM

PRODUCER COUNTY AGENTNAME____________________________ NAME___________________________ADDRESS_________________________ PARISH__________________________ _________________________ FIELD NUMBER___________________PHONE___________________________VARIETY__________________________ #OF ACRES_______________________DATE OF EMERGENCE_________________________________________________SEEDING METHOD: WATER_________ DRY (SOIL)______________________

PLEASE RETURN TO YOUR COUNTY AGENT

Figure 24. D-D50 Rice Management Program Enrollment Card

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Louisiana DD-50 Rice Management ProgramMID-SOUTH Agricultural Weather Service Center, Stoneville, Miss.National Weather Service and Louisiana Cooperative Extension Service, cooperating

Rice Farmer Acadia123 Able Crowley 1998Crowley, LA 70527

FIELD-NO FIELD-NAME ACRES VARIETY SEEDED1 Cypress 125 Cypress Water2 Maybelle 110 Maybelle Water3 Bengal 100 Bengal Dry4 Mars 75 Mars Water

FLD 1 FLD 2 FLD 3 FLD 41 Effective Planting Date 0/0 0/0 0/0 0/02 Date of Emergence 4/20 4/22 4/23 4/253 First Tiller 5/4 5/9 5/12 5/124 Drain for Straighthead 5/19 5/17 5/23 5/235 Begin Checking Internodes 5/29 5/27 6/2 6/26 Check for pH 6/5 6/3 6/11 6/117 Early Boot 6/21 6/13 6/25 6/258 Heading 6/30 6/22 7/6 7/69 Harvest 8/4 7/27 8/20 8/20

NOTE: These are just predictions. Fields must be closely monitored to assure proper growth stages.

Louisiana DD-50 Rice Management Program

LSU Ag Center Recommendations - Numbers in the margin correspond to the growth stages listed onthe prediction printout.

2 Emergence equals 8-10 seedlings visible per square foot for drill-seeded rice and seedlings around3/4 inch (average) for water-seeded rice. Pinpoint flood may be started at this time. If Karate is to beused for water weevil control, begin scouting as soon as the field has been flooded or flushed. Treatwhen adults are present. Continue to scout at least weekly. Two or more applications may be required.

3 Majority of plants displaying first tiller. Under normal conditions, nitrogen should be applied and afield permanently flooded by this time (dry-seeded or prolonged seeded drained fields). Research hasshown that 70% to 100% of nitrogen should be applied to a dry (if possible) soil surface within 7 daysbefore the permanent flood is applied. If propanil is used, begin flooding within 24 hours of application.In cold, cloudy weather, delay flood 4-5 days to enhance propanil activity.

4 Where straighthead is a potential problem, fields should be drained, dried and reflooded before thegreen ring stage.

5 Begin checking for internode elongation (green ring) stage. This is normally the best time for a mid-season nitrogen application (if needed). Begin scouting for foliar diseases. Apply phenoxy herbicides atthe first green ring. Do not apply after the second green ring stage. This is the earliest recommendedtiming for application of any fungicide. If Moncut fungicide is to be used, the first application at 0.7 to1.0 lb. per acre should be made now with a second application at the same rate to follow in 10 to 14days.

6 Panicle differentiation (panicle 2mm), mid-season nitrogen should be applied at least by this time.If Tilt fungicide is to be used and two (6 ozs. per acre) applications are intended, apply the first at orshortly after this stage. If Quadris is to be used for sheath blight control ONLY, a single application at 12.3ozs. per acre should be made 5 to 10 days AFTER panicle differentiation is reached.

7 Early boot is when there is a 1- to 2-inch panicle in the boot. First application of Benlate (1 lb. peracre) or Rovral ( 1 pt. per acre) should be made at this stage. If Quadris is to used for blast control, thefirst 12.3 ozs. per acre application should be made at this time. A second 6 ozs. per acre (or one 10 oz.per acre) Tilt application should be made at this stage, but must be made before heading.

8 Heading is when 50% of the stems are showing heads. The second Benlate (1 lb. per acre) orRovral (1 pt. per acre) or Quadris (12.3 ozs. per acre for blast control) application should be made. Beginscouting for rice stink bugs. Treatment thresholds are 30 or more per 100 sweeps during the first 14 daysafter heading and 100 per 100 sweeps from 15 days after heading until hard dough stage is reached.

9 Harvest is when a grain sample is around 20% moisture. Normally, fields should be drained two

weeks before harvest on silt loams and three weeks before on heavier (clay) soils.

Figure 25. D-D50 printout

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Rice VarietiesRice VarietiesRice VarietiesRice VarietiesRice VarietiesKent S. McKenzie, Steven D. Linscombe, Farman L. Jodari, James H. Oard and

Lawrence M. White III

Development of rice varieties has beenan important tool for improving riceproduction in Louisiana and in the UnitedStates. Release of improved varieties bypublic breeding programs in Louisiana,Texas, Arkansas, Mississippi and California,in conjunction with advancements in riceproduction technology, has provided acontinuous increase in rice production andquality. Considerable genetic potentialexists to improve on current rice varieties,and rice breeding efforts should continueto help improve production in Louisiana.

Rice Varietal Improvement ProgramIn the early days, Louisiana rice

production depended on varietalintroductions by individuals. In 1909, thefirst rice breeding program in the UnitedStates was initiated when the RiceResearch (Experiment) Station wasestablished at Crowley. The rice breedingactivities there were under the direction ofUSDA scientists from the inception of theprogram until the Louisiana AgriculturalExperiment Station (LAES) assumedresponsibility for the program in 1981.

Rice VarietiesRice VarietiesRice VarietiesRice VarietiesRice VarietiesKent S. McKenzie, Steven D. Linscombe, Farman L. Jodari, James H. Oard and

Lawrence M. White III

2424242424

Since its inception, the program hasformally released 26 improved ricevarieties (Table 2).

To develop a new rice variety, abreeder must first create new geneticcombinations. Artificial hybridization is themost common method used to achieve thisgoal. Old varieties, breeding lines, foreignintroductions and mutations compose thepool of genetic materials known asgermplasm. From this germplasm, thebreeder selects materials with desirablecharacteristics to use as parents in thehybridization program. The secondgeneration of offspring from hybridizationwill contain thousands of differentcombinations of the parents’ characteristics.This is the result of the transfer andrecombination of the genes from theparents, and such material is said to showgenetic variability. The breeder beginsselecting desirable plants in thisgenetically variable material. Theselections are grown and re-selected formany generations until the selected linesbegin to breed true. Thousands of lineswill be grown and discarded annually. Thevery best lines which survive the selectionprocess are increased and tested for yield,quality and pest resistance in the advancedtesting phase.

The testing program includes on-station,off-station and by cooperating programs.The off-station testing program includesresearch at several locations in commercialgrowers’ fields throughout the Louisianarice production area. In addition toproviding performance data in additionalenvironments, each of these off-stationlocations is used for local field days incooperation with county agents andspecialists with the Louisiana CooperativeExtension Service. These field daysprovide excellent opportunities forproducers to evaluate potential newvarieties under conditions similar to theirproduction environment. In addition,advanced testing is conducted at theNortheast Research Station near St. Joseph.The breeding project also conductscooperative advanced testing with publicrice breeders in Arkansas, California,

Florida, Mississippi and Texas. Cooperativeevaluations of advanced materials are alsoconducted with breeders and plantpathologists in Argentina, Columbia, Italyand Uruguay.

Typically, eight to 10 years arenecessary from the artificial hybridizationuntil seed of a new variety is madeavailable to rice producers. A typicalsequence of steps in the development of anew variety is illustrated in Table 3 usingthe new variety Lafitte as an example.

The breeding project uses a winternursery facility in Lajas, Puerto Rico, tofacilitate varietal development. Thenursery typically turns over earlygeneration material to speed the intervalfrom artificial hybridization to early yieldtesting. The nursery is also often used toincrease and purify seed of potentialreleases. The breeding project, incooperation with biotechnologists at theRice Research Station, also uses antherculture to expedite development ofhomozygous (pure) lines, which candecrease the time from hybridization toinitial yield evaluation.

The rice breeding project dependsheavily on many cooperating projects forassistance in the development andevaluation of experimental lines.Cooperators include agronomists,entomologists, pathologists,biotechnologists, geneticists, weedscientists, food scientists and physiologists.This cooperation is essential for thesuccess of varietal improvement effortsaimed at numerous characteristics,including but not limited to yield, millingquality, cooking quality, insect resistance,disease resistance, herbicide tolerance,seedling vigor, lodging resistance, fertilizerresponsiveness, stress tolerance, earlinessand ratooning.

The Rice Breeding and cooperatingprojects also evaluate potential varietalreleases from other breeding projects (bothprivate and public) to determine theiradaptability under Louisiana growingconditions. Many rice varieties from out-of-state breeding programs are well adaptedto Louisiana and are widely grown.

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Rice Varieties: Characteristics andPerformance

The two primary grain types grown inLouisiana are long grain and medium grain.Long grains are characterized by a grainlength:width ratio of more than 3:1 andtypically cook dry and fluffy because of ahigh to intermediate gelatinizationtemperature characteristic and a relativelyhigh amylose content. Medium grainstypically have a length:width ratio ofbetween 2:1 and 3:1 (usually closer to 3:1)and cook soft and sticky because of a lowgelatinization temperature characteristicand a relatively low amylose content.Southwestern Louisiana producers havehistorically planted from 20 percent to 50percent of rice acreage in medium grains,and those in northeastern Louisiana growalmost exclusively long-grain varieties. Inrecent years, the percentage of the staterice acreage planted to medium grains hascontinually decreased. Interest in specialpurpose varieties has gained in popularity.These varieties have distinctly differentcooking quality attributes, such as aroma,elongation or a unique cookingcharacteristic that may be favored by manyethnic populations living in the UnitedStates as well as other consumersinterested in gourmet or premium rice.The major specialty types include softcooking aromatic Jasmine, flaky cookingelongating and aromatic Basmati, Kokuhoe,waxy, standard long-grain aromatic Della,soft cooking non-aromatic Toro and otherless known gourmet types. Most specialtyrice marketed in the United States isimported from Thailand, India andPakistan. Efforts are under way at the RiceResearch Station to develop adaptedvarieties that can be used in the domesticproduction of imported specialty types. Anumber of specialty varieties from theDella, Toro and Jasmine groups are underlimited production in the southern UnitedStates.

Table 4 displays agronomic, yield andquality characteristics of thoserecommended for Louisiana production in1998. Data were generated in thecommercial variety tests from variouslocations throughout Louisiana.

The following information is included:Days to 50% heading: Average number of

days from emergence to 50 percentheading. Most varieties will reachharvest maturity (20 percent grainmoisture) within 30 to 40 days afterheading under normal conditions.

Seedling vigor: Visual estimate.Plant height: Height at maturity in inches

from soil line to extended panicle.Lodging: Comparative estimate of resis-

tance to lodging. Most varieties rated asresistant to lodging can lodge, especiallyunder excessive levels of appliednitrogen. Abbreviations are: HR = highlyresistant, R = resistant, MR = moderatelyresistant, MS = moderately susceptible, S= susceptible, HS = highly susceptible.Resistance to lodging is generallyinfluenced by both plant height andstraw strength.

Grain yield: Dry weight (converted to 12percent moisture), lb/A.

Milling: a) Head = % of whole kernelsafter milling; b) Total = % of all kernels(whole and broken) after milling.

Recommended VarietiesThe following section provides specific

information about each recommendedvariety. The location in parenthesesindicates origin of the variety.

Jodon (Louisiana): Jodon is asemidwarf, long-grain variety that is asister line to Cypress. It has displayedgood levels of resistance to lodging butmay lodge more readily than Lemont-typesemidwarfs. This variety has very goodseedling vigor and excellent first andsecond crop yield potential. Milling yieldsare generally fair to good. Jodon issusceptible to sheath blight and blast andto straighthead. Jodon has amylographiccharacteristics similar to L-202, which maymake it cook slightly softer than other longgrains and, thus, be unsuitable for canningprocesses.

Jackson (Texas): Jackson is a sisterline to Maybelle (developed from thesame cross), but it is seven to 10 days laterin maturity and 2 to 3 inches taller thanMaybelle. Jackson typically is superior toMaybelle in first crop yield potential. The

2626262626

variety is susceptible to sheath blight andblast diseases; second crop potential isvery good.

Alan (Arkansas): Alan is taller andsomewhat more susceptible to lodgingthan the other varieties in this group. Firstand second crop yield potential is good.Milling yields are generally fair to good. Ithas excellent seedling vigor. Alan issusceptible to sheath blight and blast.

Maybelle (Texas): Maybelle is theearliest maturing variety recommended forLouisiana. Although Maybelle is not asemidwarf, it displays fairly goodresistance to lodging. It displays excellentseedling vigor and has good first crop andexcellent second crop yield potential. It issusceptible to blast and sheath blight.

Drew (Arkansas): Drew is aconventional height, early long-grainvariety very similar in appearance toKaybonnet. It has excellent resistance topredominant blast races. Yield potential ofthe variety is excellent and milling yieldsare typically good. It is moderatelysusceptible to lodging and will standsomewhat better than Kaybonnet.

Kaybonnet (Arkansas): Thisconventional height, early long-grainvariety has displayed excellent yieldpotential and good milling characteristics.The variety has very high levels ofresistance to most races of blast commonto Louisiana. Kaybonnet is rated assusceptible to sheath blight disease andmoderately susceptible to lodging. It hasdisplayed second crop potential.

Cypress (Louisiana): Cypress is anearly semidwarf long grain that ismoderately resistant to lodging. It issomewhat more susceptible to lodgingthan Lemont, and this is especially apotential problem under excessive rates ofnitrogen fertilizer. Cypress has displayedexcellent first crop and good second cropyield potential. It has very good seedlingvigor. Milling yields are very good andmay not be as adversely affected by sub-optimum harvest moistures as other long-grain varieties. This is primarily associatedwith superior resistance to fissuring.Cypress is susceptible to sheath blight andblast diseases.

Lemont (Texas): Lemont is asemidwarf that has displayed very highyield potential, as well as excellent millingcharacteristics. It has poor seedling vigor,and shallow seeding depth is essential.Because of the short plant height and goodstraw strength, Lemont is highly resistant tolodging. Lemont is very susceptible tosheath blight and susceptible to blast. Ithas shown very good ability to tiller (stool)and good second crop potential.

Rico 1 (Texas): This variety hasexcellent yield potential and good millingperformance. It has typically yieldedhigher than other recommended medium-grain varieties in yield trials. It is a tallvariety and is susceptible to lodging,especially if nitrogen fertilization rates aretoo high. Seedling vigor is fair. It ripensvery slowly, maturing about one weeklater than Mars. It is moderately resistant tostraighthead, moderately susceptible tosheath blight and susceptible to sheath rotand blast. Rico 1 is characterized by short,plump grains, making it more difficult todry under certain conditions. It also tendsto produce chalky grains, especially underhigh nitrogen fertilization. As a result,some mills may be reluctant to accept it.

Bengal (Louisiana): Bengal is asemidwarf variety that has displayed verygood yield potential and excellent millingquality. The milled grains are plumperthan other commonly grown mediumgrains in the South, a characteristic favoredfor some processing uses. Seedling vigoris good, and Bengal has displayed goodsecond crop yield potential. It issusceptible to blast and straighthead andmoderately susceptible to sheath blight. Ithas displayed susceptibility to panicleblight.

Lafitte (Louisiana): Lafitte is a short-statured medium grain that is five to sixdays earlier in maturity than Bengal. It is 2to 3 inches taller than Bengal and is moresusceptible to lodging. It has displayedgood stable yields and consistently hadhigher head rice yields in testing. Lafitte isresistant to the predominant blast races.Seedling vigor is good, and the variety hasdisplayed good second crop potential inlimited testing. It is moderately susceptible

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to sheath blight and susceptible tostraighthead.

Other VarietiesOther VarietiesOther VarietiesOther VarietiesOther VarietiesThis section provides information on

varieties that are not generallyrecommended but may be grown onlimited acreage.

Dixiebelle (Texas): The variety has aNewrex-type cooking qualitycharacterized by 2 percent to 3 percenthigher amylose content than conventionalU.S. long grains. This cooking quality typeis favored by the rice canning industry andshould be grown on a contract basis. It hasfair yield potential and milling quality. It isa semidwarf and has good resistance tolodging. This variety has very poorseedling vigor.

Gulfmont (Texas): This semidwarfvariety is very similar to Lemont. Gulfmonthas normally been somewhat earlier inmaturity than Lemont. It has very goodsecond crop potential. Milling yields havebeen good. Disease reactions are similar toLemont.

Jefferson (Texas): Jefferson is asemidwarf long grain that is about thesame maturity as Jodon, Jackson and Alan.About the same height as Lemont, it ishighly resistant to lodging. Milling yieldsare good, but seedling vigor is poor.Jefferson is susceptible to sheath blightand moderately susceptible to blast.

Katy (Arkansas): Katy has a high levelof resistance to blast disease. It is tall,moderately susceptible to lodging and hasgood seedling vigor. The variety hasshown more resistance to sheath blightthan other varieties in this maturity group.It is moderately susceptible tostraighthead. Katy has moderate yieldpotential.

Lacassine (Louisiana): Lacassine isless leafy than Lemont or Gulfmont, andthe panicle is more prominently displayed.Lacassine, like Lemont and Gulfmont, ishighly susceptible to sheath blight andsusceptible to blast. It has good first andsecond crop yield potential. Lacassine alsohas somewhat poor seedling vigor in adry-seeded system, and shallow seedingdepth is important.

LaGrue (Arkansas): LaGrue is a 1993very early, long grain release. This varietyis about 43 inches tall and moderatelysusceptible to lodging. LaGrue hasexcellent yield potential. Milling yields arevariable, generally averaging less thanrecommended varieties in this maturitygroup. LaGrue is susceptible to blast andsheath blight.

Litton (Mississippi): Litton is a short-statured long grain that has had onlylimited testing in Louisiana. It has averaged1 to 2 inches taller than Cypress butappears to have fairly good resistance tolodging. Litton is two to three days later inmaturity than Cypress.

Mars (Arkansas): This variety hashigh yield potential and generally goodmilling characteristics. Mars is a stiff-strawed variety moderately susceptible tolodging. It is susceptible to blast.Straighthead may also be a problem.Seedling vigor is generally quite good.

Millie (Arkansas): Millie is a veryearly, long-grain variety that is fairlyresistant to lodging. It has moderate yieldpotential and excellent millingcharacteristics. It is susceptible to blast andmoderately susceptible to sheath blight.Millie has exhibited substantial injuryfrom several widely used riceherbicides.

Priscilla (Mississippi): Priscilla is asemidwarf early long grain variety that hasshown good yield potential. It is slightlytaller and slightly earlier than Lemont.Milling yields are fair.

Saturn (Louisiana): Saturn is an old(released in 1964) medium-grain varietystill grown in southwest Louisiana. Thevariety has good seedling vigor but is talland extremely susceptible to lodging.Saturn has moderate yield potential andexcellent milling characteristics.

Special Purpose VarietiesThese varieties have special cooking or

processing characteristics. They aregenerally grown on a limited acreage.Because of their unique cookingcharacteristics, they should not be co-mingled with standard U.S. long-grainvarieties.

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Jasmine 85 (Texas): Jasmine 85 is anaromatic, soft-cooking rice. Because of lowamylose content, its grains tend to sticktogether when cooked. Agronomically, it isa true semidwarf but is somewhat tallerthan Lemont. It is susceptible to lodging,very resistant to blast, moderately resistantto sheath blight, very susceptible tostraighthead and moderately susceptible topanicle blight. Its yielding ability is goodto excellent, but milling yields are inferiorto current varieties. Because of thenoticeable differences in the specialtyqualities of Jasmine 85 and importedJasmine, this variety has not been widelyaccepted by the traditional consumers ofJasmine rice. Markets should be identifiedfor this cultivar before it is planted.

Toro-2 (Louisiana): Toro-2 is anonaromatic, low amylose (sticky cooking)long-grain special purpose variety. In tastetests, Toro-2 was judged to haveacceptable Toro-type cooking and tastecharacteristics. A true semidwarf variety, itis resistant to the predominant blast racesand moderately susceptible to sheathblight. It is very susceptible tostraighthead.

Della (Louisiana): Della is an aromaticstandard long-grain rice favored for itsunique popcorn aroma and tastecharacteristics. It is grown on limitedacreage in Louisiana. Della is a midseasonvariety and displays low yield potentialcompared to other varieties. Diseasesusceptibility is often a problem becauseDella is susceptible to most major ricediseases. It is tall and very susceptible tolodging, even under conditions of lowyield potential.

Dellrose (Louisiana): Dellrose is aDella-type aromatic long-grain varietyrecently released by the LAES. Taste panelevaluations indicate similar aroma andflavor ratings between Della and Dellrose.Chemical analysis of rice aroma compoundshows the aroma intensity of Dellrose tobe higher than Dellmont and lower thanDella. Dellrose is a semidwarf variety withhigh grain yield, high milling yield andhigh ratoon yield potential. It is susceptibleto sheath blight, moderately susceptible to

blast and moderately resistant tostraighthead.

Akitakomachi (Japan): This variety isgrown on a very limited acreage for thepremium quality market. It is a true shortgrain with limited yield potential and isvery susceptible to lodging. It should notbe grown unless a market has beenidentified.

SummaryVariety selection is a critical early step

in a successful program. No rice variety isideal, and relative strengths andweaknesses must be weighed in selectingvarieties for each operation. It is generallyrecommended to plant several varieties tominimize potential problems with adverseweather and disease epidemics. With thisin mind, it is beneficial to plant varietieswith differential relative strengths andweaknesses, especially relative to diseasesusceptibility.

For additional updated varietalinformation, check the Extension Service’spublication 2270, Rice Varieties andManagement Tips, revised each year.

Seed CertificationOnce a new variety has been

developed, a mechanism is needed topurify, maintain and distribute high quality,genetically pure seed to the rice industry.Seed certification accomplishes this andprovides an operating procedure toachieve high quality seed and to guaranteeit to the user.

The foundation seed rice program ofthe Rice Research Station is the first phasein the seed certification process. A smallamount of seed of a new variety issupplied by the breeder to the foundationseed project. Single rice panicles aregrown in individual rows (one panicle perrow) called headrows. This allows thebreeder and foundation seed personnel topurify and discard mixtures, off types oroutcrosses. Acceptable headrows arecombined in bulk to produce breeder seed,which is maintained by the foundationseed project and used to plant the next

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Table 2. Principal rice varieties released from the Rice Research Station Table 2. Principal rice varieties released from the Rice Research Station Table 2. Principal rice varieties released from the Rice Research Station Table 2. Principal rice varieties released from the Rice Research Station Table 2. Principal rice varieties released from the Rice Research Station in Crowley in Crowley in Crowley in Crowley in Crowley.....

____________________________________________________________________

Grain YearVariety C.I./P.I. No. type released Breeders Involved____________________________________________________________________Colusa 1600 short 1917 Chambliss, JenkinsFortuna 1344 long 1918 Chambliss, JenkinsAcadia 1988 short 1918 Chambliss, JenkinsDelitus - long (A) 1918 Chambliss, JenkinsTokalon - long 1918 Chambliss, JenkinsEvangeline 1162 long 1918 Chambliss, JenkinsRexora 1779 long 1928 Chambliss, JenkinsNira 2702 long 1932 Chambliss, JenkinsMagnolia 8318 medium 1945 JodonLacrosse 8985 medium 1949 JodonSunbonnet 8989 long 1953 JodonToro 9013 long 1955 JodonNato 8998 medium 1956 JodonSaturn 1415 medium 1964 JodonDella 9483 long (A) 1973 JodonVista 9628 medium 1973 Jodon, McIlrathLA 110 9962 medium 1979 McIlrath, JodonLeah 9979 long 1982 Trahan, JodonToro-2 483070 long 1984 McKenzie, JodonMercury 506428 medium 1987 McKenzieLacassine 548772 long 1991 Linscombe, JodariBengal 561735 medium 1992 Linscombe, JodariCypress 561734 long 1992 Linscombe, JodariJodon 583831 long 1994 Linscombe, JodariDellrose 593241 long (A) 1995 Jodari, LinscombeLafitte 593690 medium 1996 Linscombe, Jodari

(A) = Aromatic.

stage in the seed certification process. Thefoundation seed project uses this smallamount of breeder seed to plant andproduce foundation seed. It is distributedfrom the Rice Research Station tocommercial seed growers who haveapplied through a county agent for anallotment of foundation seed of a particularvariety. Allocation of the foundation seedrice in Louisiana is directed by theLouisiana Seed Rice Growers Association.

The next generation in the seedcertification process is registered seed,which is grown by commercial seed ricegrowers from the foundation seed

provided by the Rice Research Station.Registered seed is used to produce the lastgeneration, certified seed, in thecertification process. In some instances,certified seed may be produced directlyfrom foundation seed. Certified seed isused by farmers to plant rice crops formilling and cannot be used to produceseed in the seed certification process.

The official seed certifying agency inLouisiana is the Louisiana Department ofAgriculture and Forestry. This agencyestablishes the guides for all aspects of thecertification process. All levels of thecertification process from breeder seed to

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certified seed are monitored, inspectedand tested by the Louisiana Department ofAgriculture and Forestry. Below are theRice Seed Certification standards.

Isolation RequirementsFields offered for certification must be

clearly separated from other fields by aditch, levee, roadway, fence or barren

Table 3. Sequence of events in the development of the rice variety Lafitte.Table 3. Sequence of events in the development of the rice variety Lafitte.Table 3. Sequence of events in the development of the rice variety Lafitte.Table 3. Sequence of events in the development of the rice variety Lafitte.Table 3. Sequence of events in the development of the rice variety Lafitte.

Step Year ID Number Stage of Development

1 1988 88CR018 (winter cross) Artificial hybridizationMercury & x Mercury/Koshihikari

2 1988 88T1020 F1 - Space plant nursery3 1989 89F7034 F2 - Bulk - segregation4 1990 9010848 F3 - Headrow - segregation5 1991 9120071 F4 - Headrow - segregation6 1992 9205777 F5 - Preliminary yield test

- Purification7 1993 9302008 F6 - Uniform Regional Nursery

(URN)(Arkansas, Louisiana, Texas,Mississippi, California, Florida)

- Advanced yield test (AY)(Five locations in Louisiana) - Purification

8 1994 9302008 F7 - URN - AY Commercial variety test (CV) (Five locations in Louisiana) - Purification

9 1994 9302008 (Puerto Rico) F8 - Headrow increase10 1995 9302008 F9 - URN - AY - CV

Breeder-Foundation seed field11 1996 Lafitte F10 - Release to seed growers

Table 5. Isolation Requirements Table 5. Isolation Requirements Table 5. Isolation Requirements Table 5. Isolation Requirements Table 5. Isolation Requirements

No. of Feet From Same Variety/ No. of Feet from Other Varieties/ Different Class Planted By All Classes Planted By

Ground Air Ground AirDrill Broadcast Right Parallel Drill Broadcast Right Parallel

Angle Angle

10 10 1,320 10 20 100 1,320 100

strip aminimumof 10feet iftheadjoiningcrop isthe samevarietyand class.

Inaddition,

the following isolation distances willpertain if the adjoining crop is a differentclass or different variety (Table 5).

Any part of the applicant’s field orfields closer than these distances must beharvested before the final inspection orplowed up. Failure to comply with thisrequirement will disqualify the entire field(Table 6).

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Table 4. Agronomic, yield and milling characteristics of recommendedTable 4. Agronomic, yield and milling characteristics of recommendedTable 4. Agronomic, yield and milling characteristics of recommendedTable 4. Agronomic, yield and milling characteristics of recommendedTable 4. Agronomic, yield and milling characteristics of recommendedrice varieties, 1998.rice varieties, 1998.rice varieties, 1998.rice varieties, 1998.rice varieties, 1998.

Maturity and Days tograin type Yield Milling % Seedling 50% Heightgroup (lb/A) (head-total) vigor heading (in) Lodging

Very Early Long Grain

Jodon 7271 60 - 69 Good 90 38 MRAlan 7173 59 - 69 Good 90 42 MSJackson 7047 59 - 70 Good 91 41 MRMaybelle 6074 60 - 70 Very good 85 38 MR

Early Long Grain

Drew 7831 64 - 70 Very good 95 46 SKaybonnet 7729 63 - 70 Very good 95 45 SCypress 7259 66 - 70 Very good 95 40 MRLemont 6750 61 - 70 Fair 97 38 HR

Medium Grain

Rico 1 8373 60 - 69 Fair 97 44 SBengal 7896 65 - 70 Good 96 38 MRLafitte 7290 67 - 70 Good 89 39 MS

Special Purpose

Dellrose 6789 63 - 71 Fair 94 40 HRToro-2 6020 61 - 71 Fair 97 43 MRDella 5642 58 - 69 Fair 96 51 HS

Table 6. Field StandardsTable 6. Field StandardsTable 6. Field StandardsTable 6. Field StandardsTable 6. Field Standards

Factor Breeder Foundation Registered CertifiedLandrequirement 1 year 1 year 1 year 1 yearOther varieties None None 10 plants/A 25 plants/AHarmful diseases* None None None NoneNoxious weeds:Red Rice(including Black Hull Rice) None None None 1 plant/10 ASpearhead None None None 2 plants/ACurly Indigo None None 4 plants/A 4 plants/A* Diseases seriously affecting quality of seed and transmissible by planting stock.

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Soils, Plant Nutrition and FertilizationSoils, Plant Nutrition and FertilizationSoils, Plant Nutrition and FertilizationSoils, Plant Nutrition and FertilizationSoils, Plant Nutrition and FertilizationPatrick K. Bollich, John K. Saichuk and Eddie R. Funderburg

Soils, Plant Nutrition and Fertilization Soils, Plant Nutrition and Fertilization Soils, Plant Nutrition and Fertilization Soils, Plant Nutrition and Fertilization Soils, Plant Nutrition and Fertilization Patrick K. Bollich, John K. Saichuk and Eddie R. Funderburg

Rice requires an adequate supply ofplant nutrients throughout the growingseason. Four major nutrients and onemicronutrient are required by rice inLouisiana. Nitrogen (N) is required onvirtually all soils where rice is produced,and it is the single most important nutrientnecessary for maximizing yields. Rice alsorequires relatively large amounts ofphosphorus (P) and potassium (K) oncertain soils, especially the prairie andflatwoods soils of southwest Louisiana. Thealluvial soils (clay and clay loams) incentral and northeast Louisiana are typicallyhigh in these nutrients and do not respondto P and K applications. Deficiencies in Pand K can occur on these soils iflandforming operations remove topsoil.Sulfur (S) is adequately supplied by mostrice soils unless native fertility is inherentlylow or topsoil has been removed. Zinc(Zn) is the only micronutrient known to bedeficient on some rice soils. As with S, Zndeficiencies occur when native levels arelow, where topsoil has been removed andalso when cool weather retards root growthduring the seedling stage.

Behavior of nutrients in rice is quitedifferent from that of upland crops.Because rice is cultured under floodedconditions, it is important to understand therelationship between nutrient availabilityand flooded soils to manage these nutrientsproperly.

NitrogenIn drained soils, N is present in both the

ammonium and nitrate form, and the riceplant is capable of using either. Nitrate Ncannot be maintained once a rice soil isflooded, and large losses of N occurthrough denitrification. Ammonium N isvery stable under flooded conditions andremains available to the plant as long asthe flood is maintained. Prolonged drainageand aeration of the soil convert theammonium form of N from both the soiland chemical fertilizers to nitrate. Once thesoil is reflooded, any nitrate N is lost

rapidly. It is important to flood a rice soilpermanently once fertilizer N is applied.

PhosphorusPhosphorus is present in the soil in

organic and inorganic forms. As with allnutrients required by rice, organic formsare not available to the plant. Since organicP is slowly converted to the inorganicform, fertilizer applications of P are veryimportant on soils deficient in this nutrient.

Flooding a rice soil increases theavailability of soil P to the plant.Alternating flooding and draining cycleshas a significant effect on P availability.When the soil is drained and aerated, P ismuch less available to the plant.Reflooding will enhance additional Prelease but a short-term deficiency mayoccur even where adequate P is present.

PotassiumSoil K is less affected by flooding than

N or P. Its availability changes very littlewith draining and flooding. Potassium isless limiting to growth and grain yield thaneither N or P, and deficiencies in K havebeen less frequent than in other nutrients.Potassium nutrition is closely associatedwith the rice plants’ ability to resist disease,and more emphasis is being placed on therole it plays in overall rice plant nutrition.

SulfurMost of the S contained in the soil is in

the organic form under both flooded andunflooded conditions. Inorganic S resultsfrom the decomposition of organic matter,and the S status of a soil is related to theamount of organic matter present. Some Sis also provided by precipitation andirrigation water.

ZincZinc availability is affected by flooding,

although the change in soil pH in responseto flooding is the reason for the fluctuationin available Zn. It is more available whenthe soil pH is acidic. Since soil pH moves

3333333333

toward neutral under flooded conditions,Zn becomes less available in acid soilsover time and more available on alkalinesoils.

Other NutrientsMany other nutrients play a role in rice

plant nutrition, and flooding hasdifferential effects on their availability.Availability of calcium (Ca) andmagnesium (Mg) is not affected to a greatextent by flooding. Iron (Fe), manganese(Mn), boron (B), copper (Cu) andmolybdenum (Mo) become more solubleunder flooded conditions. While thesenutrient elements are known to play a rolein rice plant nutrition and critical levels inrice plant tissue have been established,documented deficiencies or toxicities havenot been recognized in Louisiana.

Rice Plant Nutrition and FertilizationThe most frequently limiting plant

nutrients in Louisiana rice in order ofimportance are N, P, K and Zn. Soil type,native soil fertility, cropping history andagronomic management practicesdetermine when and to what extentdeficiencies of these nutrients occur. A soiltest is valuable in predicting nutrientdeficiencies and appropriate correctivemeasures. A sound fertility program isessential to maximize yields and use plantnutrient inputs efficiently. Many nutrientdeficiencies can be corrected oncerecognized in the field, but providingrequired nutrients in sufficient amounts toavoid deficiencies is the best approach toassure maximum rice yields.

Proper fertilizer management isimportant to increase profitability,minimize inputs, improve nutrientefficiency and mitigate environmentalconcerns. Efficient fertilizer use requires:1) proper water management in relation tofertilizer application, 2) selection of theproper fertilizer source, 3) timelyapplication of fertilizers by methods thatprovide optimum rice growth, grain yieldand crop quality and 4) application of theproper amount of fertilizers to ensureoptimum grain yields and economicreturns. The major plant nutrients required

for rice production and their propersource, time of application and rate arediscussed in the following sections.

Nitrogen Nutrition, WaterManagement, Source and Timing

Nitrogen is the most limiting plantnutrient in rice. Maximum yields dependon an adequate supply of N. SuboptimumN applications can decrease yield potentialand grain quality and increase theincidence of disease. Deficiencysymptoms include yellowing of the olderleaves, reduced tillering, browning of leaftips and shorter plants (Figs. 26-28).Excessive N causes lodging in somevarieties, increases the incidence ofdisease and can cause grain sterility.Because of the relation between Nbehavior and flooded soils, the efficiencyof N in rice is greatly influenced by watermanagement.

Rice is a semiaquatic plant that hasbeen bred and adapted to flooded culture.Flooding a rice soil (1) eliminates moisturedeficiency, (2) increases the availability ofmost nutrients essential to plant nutrition,(3) suppresses weed competition and (4)provides a more favorable and stablemicroclimate for plant growth anddevelopment.

A permanent flood of 2 to 4 inchesshould be established as soon as possibleand maintained throughout the growingseason. In dry-seeded rice, apply thepermanent flood by the 4th or 5th leafstage (20 to 35 days after planting).Uniform, level seedbeds allow earlierflooding, which improves nutrientavailability and weed control. To avoidstand loss and reduced seedling vigor, dry-seeded rice should not be submerged. Inwater-seeded rice, a shallow flood isestablished before planting. Rice seedlingseither emerge through a permanent flood(continuous flooding) or the field is brieflydrained to encourage seedling anchorageand uniform stand establishment (pinpointflooding). The field is then reflooded, andthe seedlings emerge through the water asin the continuously flooded system.

Avoid draining rice fields afterpermanently flooding unless extenuating

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circumstances exist. Removing thefloodwater can result in loss of N, mayaffect the availability of many othernutrients, encourages additional weedgrowth and increases the incidence ofsome diseases. Situations that justifydraining include: 1) soils susceptible tostraighthead, 2) severe Zn deficiency, 3)application of some herbicides and 4)control of the rice water weevil larvae.

Ammonium sulfate and urea are themost common sources of N in rice. Thesetwo sources are equally effective whenproperly applied. An advantage of urea isits higher N analysis of 46 percent. It is amore economical source since less materialis applied per unit of N. Ammoniumsulfate contains 21 percent N, and morethan twice the amount of material needs tobe applied per unit of N. Ammoniumsulfate also contains 24 percent S, whichmakes it an excellent fertilizer source foravoiding or correcting S deficiencies. Itmay be a slightly more effective N sourcewhen N must be applied to saturated soilsduring the seedling stage. Nitrate forms ofN should never be used because of thepotential for large losses of N caused byleaching and denitrification.

The ammonium form of N in either ureaor ammonium sulfate is very stable inflooded soils and remains availablethroughout the season. Once N has beenapplied and the field permanently flooded,soil drying should be avoided or theammonium N will be converted to nitrateN. This conversion process results in lossof N through denitrification once the fieldis reflooded.

Nitrogen fertilizer timing depends onthe cultural system used. A continuous,available supply of N must be maintainedin the soil-plant system to maximizeproduction. The relationship between Ntiming and water management affects Nretention, efficiency and use. Theapproach to N management in apermanently flooded system (continuous orpinpoint) and a delayed flood system (dryseeded, or water seeded with a delayedflood) is quite different.

In the permanently flooded system, allor most of the total N requirement should

be incorporated into a dry soil 2 to 4inches deep before flooding. Brieflydraining the field after seeding toencourage seedling anchorage in apinpoint flood system will not result in lossof N unless the soil is permitted to dry. Itis important to maintain the seedbed incomplete saturation to conserve applied N.Additional N should be applied atmidseason as needed unless the totalrequirement was preplant incorporated.

In the delayed flood systems (drill, drybroadcast or water seeded), the permanentflood may not be established until three tofour weeks after seeding. It is impracticalto apply large amounts of N at seeding inthese systems since fertilizer N cannot bestabilized or maintained beforepermanently flooding. On most soils, it isnecessary to provide 15 to 30 pounds of Nduring the seedling stage to encouragerapid growth and development. Only 10percent of this amount should be includedin the total requirement. All or most of therequired N should be applied to a dry soilby the 4th to 5th leaf stage just beforepermanently flooding. The floodwatersolubilizes the N and moves it down intothe soil where it is retained for plant useduring the growing season. Applyadditional N at midseason as needed unlessthe total amount required was appliedpreflood.

In either a permanent or delayed floodsystem, an adjustment in N management isnecessary when rice fields are drained forstraighthead. Straighthead is a physiologicaldisorder (Fig. 29) that occurs on sandysoils, on soils where arsenical herbicideshave been previously used and on soilswhere large amounts of plant residue havebeen incorporated before planting.Significant yield losses can occur if fieldsare not drained and completely aeratedbefore panicle initiation. The drainingprocedure detoxifies arsenical compoundsand reduces the buildup of hydrogensulfide. Since draining usually occursduring midtillering, no more than 50percent to 60 percent of the required Nshould be applied preplant or preflood,with the remainder being applied beforereflooding.

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Nitrogen requirements vary with varietyand soil type. With the exception of N,soil tests can adequately predict the needfor rice nutrients. Nitrogen needs cannotbe accurately assessed by currentlyavailable soil tests. Total N requirementsare determined by conducting statewidevariety trials. Recommendations areexpressed in ranges of application ratesthat consider soil type, environment andvariety. This information is updated eachyear in the Louisiana CooperativeExtension Publication 2270, “Rice Varietiesand Management Tips.”

Research shows that the total Nrequirement can be applied preplant in acontinuously flooded system or preflood ina delayed flood system. Uniformapplication of N, familiarity with avariety’s requirement, experience with aparticular soil and proper watermanagement are critical when using thismethod. This approach may not bepractical commercially when thesesituations exist: 1) difficulty in applyinglarge amounts of N fertilizer uniformly, 2)water management capabilities areinadequate, 3) unfamiliarity with thevariety or land and 4) the seedbed issaturated. Split applications may be moredesirable when any of these conditionsexist.

Midseason N topdressings are usedefficiently by rice provided adequate earlyseason N was applied. A single midseasonapplication is usually sufficient tomaximize yield. Multiple applications ofmidseason N may not be cost effectiveand could reduce yield if the basal Napplication was inadequate. Unlike Napplications into the flood on seedlingrice, N applied into the floodwater atmidseason is used efficiently by ricebecause of its large plant size andextensive root system.

Rice plant growth stages have beenused to determine when to applymidseason N. The green ring growth stage(similar to panicle initiation in manyvarieties) has traditionally been used fortiming midseason N. While this growthstage is a good indicator, the overall healthof the rice crop before green ring

formation must be considered. Tissueanalyses and visual assessment areexcellent diagnostic tools to determine theN status of rice at midseason. Nitrogendeficiency should be avoided to minimizethe potential for grain yield reductions.Midseason N should be applied at theearliest indication of N deficiency, even ifthe green ring growth stage has notoccurred. Late season N applications mayalso be inefficient and could lead to grainyield reductions. Research indicates thatgrain yields are not improved when N isapplied later than four weeks after greenring. Yields may actually be reduced whenN is applied after this time.

Phosphorus Nutrition, WaterManagement, Source and Timing

Phosphorus deficiency in rice occursrather infrequently compared to Ndeficiency. Stunting, reduced tillering,delayed maturity and yield reductions canoccur when P is limiting (Fig. 30). UnlikeN, water management has little effect on Pretention unless soil loss occurs througherosion or removal of floodwatercontaining high sediment concentrations.Phosphorus availability is influenced byfertilizer placement, soil factors (pH, andFe and aluminum content) and wetting/drying cycles. Soil flooding increases theavailability of P to rice, but alternatingwetting and drying cycles can result infixation of P in the soil and temporarydeficiency.

Water soluble sources of P, such assuperphosphate and diammoniumphosphate, are effective in preventing andcorrecting mild deficiency. Consider costeffectiveness and the need for othernutrients when choosing the mostappropriate source. Factors to considerwhen determining rate of applicationinclude soil type, cropping history, growerexperience, and soil and plant tissueanalyses. Typical applications of P rangefrom 25 to 50 pounds per acre.

Phosphorus is most available to ricewhen applied at planting as a band orbroadcast and incorporated application. Ifpreplant applications are not possible,apply it before tillering occurs. Since

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adequate P is essential for tiller formation,deficiencies at this growth stage canreduce yield potential significantly.Research has shown that P applications tosoils deficient in this nutrient are lesseffective when applied after tillering hasbegun (four to five weeks after planting).

Potassium Nutrition, WaterManagement, Source and Timing

Potassium deficiencies seldom occur inLouisiana rice soils. Rice plants deficient inK are lighter green, and the leaf edgescontain rust-colored spots that give theplant a brown appearance (Fig. 31). Plantheight may be reduced, but seldom isyield reduction significant. The role Kplays in plant nutrition is probably moreimportant as it relates to disease resistance.

Potassium behavior in the soil isinfluenced little by water management.Potassium is a very soluble nutrient and isaccumulated by the rice plant throughoutthe growing season. Preplant or earlyseason application in conjunction with Nor P is recommended. Potassium chlorideand K sulfate are common sources toapply to avoid or correct existingdeficiencies. A single application (30 to 60pounds per acre) is usually sufficient tomaintain adequate K in the rice plant. Splitapplications are not necessary unless thesoil is very sandy and leaching occurs.Since most rice soils, even those with asandy plow layer, contain a clay hardpanthat restricts water infiltration, splitapplications are seldom necessary.

Sulfur Nutrition, Water Management,Source and Timing

Sulfur deficiency is difficult to diagnosebecause it resembles N deficiency. Sulfuris not mobile in the rice plant, and, whendeficiency occurs, the entire plant tends toyellow. Inadequate S in the soil andremoval of topsoil during land-formingoperations contribute to S deficiencies. Asoil test can be helpful in identifying soilareas where deficiencies might occur.Ammonium sulfate is an excellent sourceof S for correcting existing deficiencies.An application of 100 pounds ofammonium sulfate per acre will supply 24

pounds of S, an adequate amount foravoiding or correcting a deficiency in anexisting crop. Water management has noeffect on S availability or retention in thesoil, but may be important as it relates tothe application of S-containing Nfertilizers.

Zinc Nutrition, Water Management,Source and Timing

Zinc deficiency is a commonmicronutrient deficiency in rice. Earlydeficiency symptoms include chlorosis andweakened plants that tend to float on thefloodwater surface (Fig. 32). Dark brownspots develop on the leaves; whendeficiency is severe, stand loss occurs.Zinc deficiency is usually referred to asbronzing because of the rusty appearancethat develops. Calcareous soils with analkaline pH, inadequate Zn levels in thesoil, removal of topsoil duringlandforming, excessive lime applications,deep water during seedling growth andcool weather that retards root growthduring the seedling growth stage may allcontribute to Zn deficiency. Deficienciesmost often occur in early planted, water-seeded rice because of low temperaturesand poor root growth. Since stand loss canoccur when deficiency is severe, it isimportant to recognize deficiencysymptoms early.

A soil test can identify soils prone to Zndeficiency. Inorganic Zn salts, such as Znsulfate or Zn chloride, may be appliedwith other required fertilizer nutrients atplanting. In dry-seeded rice, incorporateZn to a shallow depth. In water-seededrice, Zn is more available when applied tothe soil surface in close proximity to thedeveloping root system.

Plant uptake of Zn is affected bytemperature and adequate root growth.Preplant applications of Zn do notguarantee that deficiencies will not occur.If Zn deficiencies begin to develop inseedling rice, corrective applications needto be considered. Favorable growingconditions that include high temperaturesand sunlight may help correct mild Zndeficiencies. Removal of the floodwaterfor a brief period will also alleviate mild

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Pest ManagementPest ManagementPest ManagementPest ManagementPest ManagementPest ManagementPest ManagementPest ManagementPest ManagementPest Management

deficiency. When deficiency is severe andthe potential for stand loss exists, apply Znas a foliar application. Chelated andligninsulfonate complex sources are mosteffective for correcting deficiency.

Either inorganic salts or chelated formsof Zn may be applied preplant. Inorganicforms should be applied at a rate of 8 to10 pounds of actual Zn per acre. Applychelated sources at a rate to deliver 1 to 2pounds of actual Zn. Foliar sprays shouldbe applied in a chelated form at a rate ofone-half to 1 pound of actual Zn per acre.Use the higher rate when deficiency issevere.

Fall Fertilizer ApplicationsFertilizer nutrients are most efficiently

used by rice when applied immediatelybefore seeding and no later thanpermanent flood establishment. There are

situations when fall application of somenutrients may be a suitable alternative.These include: 1) no-till and stale seedbedrice production when soil incorporation atplanting is not possible, 2) rice fieldsworked in the water prior to plantingwhen there is concern of fertilizermovement and nonuniform redistributionafter mudding in and 3) where scummingis a problem when fertilizer is applied intothe floodwater on seedling rice.Advantages to fall application of P and Kinclude more flexibility in early season Napplications and more opportunity toapply these nutrients by groundapplication. Disadvantages include poorretention of K on sandy soils because ofleaching and fixation of P on low pH soilscontaining high levels of iron andaluminum. Never apply nitrogen and Zn inthe fall.

Weed ManagementWeed ManagementWeed ManagementWeed ManagementWeed ManagementDavid Jordan and Dearl E. Sanders

IntroductionWeeds compete with rice for water,

nutrients, space and light. Direct lossesfrom weed competition are measurableand can be great. Indirect losses such asincreased costs of harvesting and drying,reduced quality and dockage at the mill,and reduced harvest efficiency are notreadily measured but can reduce profits.

Numerous grasses, broadleaf weedsand sedges can be economically damagingin rice. Weeds can grow and thrive inaquatic or semiaquatic environmentscommon to rice culture. Barnyardgrass(Figs. 33, 34), broadleaf signalgrass (Fig.35), red rice (Fig. 36), hemp sesbania(Figs. 37, 38), alligatorweed (Fig. 39),dayflower (Fig. 40), ducksalad (Fig. 41),redstem, jointvetch (Fig. 42) and annualand perennial sedges (Figs. 43-45) areamong the most common weeds. Althoughweeds vary in their ability to competewith rice, most fields contain a complexof weeds which will reduce yield andquality if an appropriate weed

management strategy is not implemented.Rice weed control is best accomplished

by using a combination of cultural,mechanical and chemical control practices.Relying on a single control practiceseldom provides adequate weed control.A thorough knowledge of the weedspresent in each field is critical indeveloping appropriate managementstrategies.

Cultural ControlPurchasing seed rice that is weed free

is an important first step in preventingweeds from becoming established,especially in the case of red rice. Red ricehas been spread largely by plantingcommercial seed that is contaminated withred rice. Red rice is a wild rice that issimilar to commercial rice. Besidesreducing commercial rice yields, the redpericarp (Fig. 46) of this noxious rice cancontaminate milled rice. Additional millingcan help remove the red discoloration butoften will lead to reduced head rice yieldsthrough breakage of kernels. Cookingattributes of rice can be altered ifsignificant amounts of red rice are present

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in milled rice. No herbicides are availablethat selectively control emerged red rice ina commercial rice field, so preventing redrice from becoming established is critical.

Presence of red rice dictates productionsystems and weed control options anddecreases flexibility. Rotating rice withother crops can reduce future weedproblems. Successful rotations withsoybeans primarily and to a lesser extentwith corn, sorghum, soybeans or cottonhave reduced levels of red rice in laterrice crops.

Proper water management is a keycomponent in controlling weeds. Severaldifferent water management schemes haveevolved in Louisiana. Permanent flood andpinpoint flood cultures were developed inwater-seeded rice to reduce weedproblems. These practices attempt tomaintain a saturated seedbed. Saturatedseedbeds prevent weed seeds fromgerminating because of the absence ofoxygen.

Establishing a good stand of rice andproviding an environment that promotesrapid growth also help to minimize weedinterference. Optimum plant populationsand adequate fertility, insect, disease andwater management contribute to the abilityof rice plants to compete with weeds.

Management of weeds is critical foroptimum rice production in both water-and dry-seeded systems. Althoughherbicide options and managementstrategies differ under these systems,managing herbicides and water in a timelymanner is critical.

Water-seeded riceMost of the rice grown in Louisiana,

especially in the southern part of the state,is water seeded to control red rice (seered rice section). Weed populations shiftfrom terrestrial weeds in dry-seededsystems to aquatic weeds in water-seededsystems. Red stem, ducksalad,alligatorweed and rushes are prevalent inwater-seeded systems. Grasses such asbarnyardgrass and broadleaf signalgrass aswell as some warm-season perennialgrasses (such as water bermuda) (Fig. 47)in some areas can be a problem also.

In water-seeded systems, Bolero orOrdram are applied before seeding tosuppress aquatic weeds and grasses. Afterseedling establishment, propanil, Arrosoloand Facet are used to control grasses andbroadleaf weeds. These herbicides areoften supplemented with Basagran tocontrol ducksalad and red stem. The fieldis generally drained briefly to exposeweeds to herbicides. When doing so, it isimportant that the soil remain wet in fieldswhere red rice is present. Allowing thesoil to dry can result in reinfestation by redrice.

Granular Ordram also controls grassesand can be applied directly in thefloodwater. Londax has become a standardfor use in water-seeded rice to controlducksalad and other difficult-to-controlaquatic weeds. Applying Londax at theappropriate timing is critical to control.Londax is applied into the floodwaterbefore aquatic weeds have surfaced, and astationary flood must be maintained forseven days for acceptable control. Somedealers offer fertilizer materialsimpregnated with Londax, an effectiveapplication that reduces cost.

Several herbicides are available forpost-flood weed control in both water- anddry-seeded systems. Facet, Blazer,Basagran, Grandstand, Londax and 2,4-Dare registered for use. Selection of theseherbicides should be based on thespectrum of weeds and restrictions on use.For example, 2,4-D use is prohibitedwhere rice is grown in close proximity tocotton and other 2,4-D-sensitive crops.Although registered for use, apply Whip360 only in salvage situations when otherherbicides have failed to control grassweeds. Excessive rice injury can occur.Precautions on variety selection andcultural practices that may contribute toinjury should be considered before use.

Dry-seeded productionIn this system, four to six weeks may

elapse between planting and permanentflood establishment, and controlling weedsduring this period is critical for maximizingyields. During this period barnyardgrass,broadleaf signalgrass, sprangletop (Fig.

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48), morningglories (Fig. 49), texasweed(Figs. 50, 51), eclipta (Fig. 52), jointvetch,smartweeds (Fig. 53) and hemp sesbaniacan become established. Timely herbicideapplications made to small weeds, flushesto activate herbicides, and establishmentand maintenance of a permanent flood assoon as possible will improve weedcontrol.

The residual herbicides Prowl, Facetand Bolero can provide residual weedcontrol up to permanent floodestablishment, and these herbicides haveproved valuable in dry-seeded production.They are especially beneficial whendelays in permanent flood establishmentare anticipated or on clay soils wherecracking of soil promotes numerous weedflushes as well as difficulty in establishingand maintaining a permanent flood.Although these herbicides do not alwaysprovide complete control, when applied ina program with propanil or Arrosolo, theseherbicides generally provide adequatecontrol up to permanent floodestablishment. These herbicides, and inparticular Facet, are more effective whenfields are flushed or when adequaterainfall occurs for activation.

Propanil, Arrosolo and Facet are usedroutinely to control emerged weeds beforeflood establishment. Propanil is a contactherbicide with no residual activity.Arrosolo contains both propanil andmolinate, and it provides contact andlimited residual weed control. Facetcontrols emerged weeds, but, unlikepropanil and Arrosolo, root absorption ofFacet is important. Flushing or adequaterainfall shortly after application of Facet isneeded for activation regardless ofwhether or not weeds have emerged.Combinations of contact herbicides such aspropanil and Arrosolo with the residualherbicides like Facet, Bolero or Prowl areoften more effective than single herbicideapplications. Weeds that are not undermoisture stress and are actively growingare controlled more easily than stressedweeds.

Grandstand, Londax, Basagran, Stormand Blazer can be applied preflood in dry-seeded systems. Propanil, Arrosolo and

Facet are generally needed for grasscontrol, and these broadleaf herbicides areused to broaden the spectrum of control.Grandstand controls morningglories,jointvetch and alligatorweed. Londax andBasagran are used to control sedges andcertain broadleaf and aquatic weeds.

Herbicide programs should bedeveloped based on the complex ofweeds present in each field. Scoutingfields and accurately identifying weeds arecritical in formulating herbicide programs.For example, Facet provides excellentcontrol of barnyardgrass but does notcontrol sprangletop. Relying on Facetalone for weed control will result insprangletop escapes which can competewith rice. An additional herbicideapplication will be needed to controlsprangletop, and the delay in applicationcaused by misidentification can makesprangletop more difficult to control.Annual sedges can often be controlledwith propanil or Arrosolo, but theseherbicides seldom control yellow nutsedgeadequately when applied alone; Basagranor Londax is generally needed.

In dry-seeded systems, pulling leveesas soon as possible after planting canimprove weed control by allowing fieldsto be flushed and flooded in a timelymanner. Without levees, using water as amanagement tool is impossible. On coarse-textured, silt loam soils, pulling levees ismuch easier than on finer-textured, claysoils. Although rainfall shortly afterplanting is beneficial for establishing a ricestand and reducing the need for flushing,excessive rainfall can prevent leveeconstruction on clay soils. Pulling levees assoon as the rice is planted when the soil isstill relatively dry can prevent or reduceproblems in preparing levees on wet soils.

Adjuvants and Spray AdditivesPostemergence herbicide performance

can be greatly influenced by adjuvants.Grandstand, Londax, Basagran, Facet andthe dry formulations of propanil must beapplied with a suitable adjuvant to controlemerged weeds. Gramoxone Extra andHarmony Extra applied as burndowntreatments require adjuvants. In contrast to

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these herbicides, adjuvants will notimprove control with emulsifiablepropanil, Arrosolo or Whip 360. Bolero,Facet (preemergence or delayedpreemergence), Prowl or Ordram appliedto the soil before weed emergence doesnot require adjuvants. When a liquidpropanil formulation or Arrosolo is appliedwith Grandstand, Londax, Facet orBasagran, additives are not needed. WhenFacet or dry formulations of propanil aremixed with these predominantly broadleafherbicides, however, an adjuvant shouldbe included.

Adjuvant cost is much lower than thecost of a herbicide application, especiallywhen several herbicides are applied as amixture. Not using an adjuvant or selectinga poor quality adjuvant can reduce weedcontrol greatly. Consult the herbicide labelfor recommendations of the type ofadjuvant (crop oil concentrate, nonionicsurfactant, etc.) and the proper rate to use.

Reduced-tillage and stale seedbedsystems

Producing rice in stale seedbed,reduced-tillage or no-till systems requiresuse of burndown herbicides appliedbefore seeding in water-seeded systemsand before rice emergence in dry-seededsystems. Timing of application willdepend on the spectrum and size ofweeds, anticipated planting date and labelrestrictions. The key is to have a weed-free seedbed when the rice emerges (dry-seeded rice) or when the flood isestablished in water-seeded systems. Aproblem associated with no-till, water-seeded rice is poor water quality and lowoxygen resulting from decaying plantresidue. Timely vegetation managementcan minimize this situation. Roundup Ultra,Gramoxone Extra, 2,4-D and HarmonyExtra are registered for use in rice.Applying combinations of Roundup Ultrawith 2,4-D or Harmony Extra increasescontrol of some broadleaf weed speciesand may broaden the spectrum of control.Each of these has strengths andweaknesses, and herbicide programsshould be tailored to control the existing

weed spectrum. Gramoxone Extra has theadvantage of rapid kill of weeds andrequires only a two-day period before theflood can be established for seeding inwater-seeded systems. This is anadvantage in controlling red rice.

These herbicides also have restrictionson preplant intervals which can potentiallylimit utility. For example, Harmony Extracannot be applied within 45 days ofplanting. Additionally, various formulationsof 2,4-D are available, and labels vary onrates and preplant intervals. ApplyingRoundup and Gramoxone Extra withresidual herbicides such as Bolero, Prowland Facet can improve early-season weedcontrol. Bolero can be applied in dry- andwater-seeded systems, and Prowl can beapplied only as a delayed preemergenceapplication in dry-seeded systems. Facetcan be applied preemergence or delayedpreemergence in dry-seeded systems. It iscritical to establish a weed-free seedbedfor the emerging rice in dry- and water-seeded systems. When weeds are notcontrolled and rice has emerged, controlcan be difficult with in-season herbicidesfor most winter annual and perennialweeds. Also, summer annual weeds thatare not controlled before rice emergencewill be older, larger and often harder tocontrol with propanil or other riceherbicides.

Weed ResistanceSome weeds have developed resistance

to herbicides. In situations where weedsare not controlled with labeled rates ofherbicides applied under environmentalconditions which are favorable forherbicide activity, these weeds may beresistant. Repeated use of propanil hasresulted in development of biotypesthroughout the Mid-South that can nolonger be controlled with propanil. Aquaticweeds in California have developedresistance to Londax. Rotating herbicidesand crops, and applying tank mixturesconsisting of herbicides with differentmechanisms of action, may prevent ordelay development of resistance inLouisiana. For example, mixtures of

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propanil with Facet, Bolero or Prowlinclude at least two different mechanismsof action and reduce selection pressure.Rotating rice with soybeans or other cropswill allow use of soil-applied herbicides orpostemergence grass herbicides which cancontrol barnyardgrass and red rice. Theseherbicides have mechanisms of action thatdiffer from most rice herbicides.

If weed resistance is suspected, contactyour county agent so an alternativeherbicide program can be developed andresistance can be monitored. In addition todeveloping potential weed resistance,repeated use of a single herbicide willexploit the weakness of the herbicide andmay shift the weed spectrum to weedsthat may be more difficult to control. Thishas been especially true in continued useof Facet only, which has resulted in a shiftfrom barnyardgrass as the primary grassweed to sprangletop.

Red Rice ManagementBecause red rice and commercial rice

are so closely related genetically,herbicides that control red rice willgenerally kill commercial rice. Watermanagement alone can often effectivelysuppress red rice and reduce competition.Presence of red rice mandates that rice beproduced in a water-seeded system,preferably the pinpoint production system.Uniform, level seedbeds are critical forsuccess. In this system, a flood isestablished with dry or presoaked riceseeded directly into the flood. Presoakedseed is preferred because it gives thecommercial rice an additional advantageover the red rice. Before flying on the riceseed, the field is tilled to muddy the waterand kill germinated red rice that wouldotherwise emerge through clear water.This type of tillage can be difficult on claysoils. Depending on environmentalconditions, the flood is removed and riceseedlings are allowed to peg into the soil.An advantage of presoaked seed is thatthe flood can be removed sooner thanwith dry rice. This can reduce the timeseeds are exposed to wind and drift withinbays and can help lead to a more uniform

stand. After rice seedlings have anchored,the flood is brought up slowly until thepermanent flood is established.Maintenance of flooded soil conditionsreduces emergence of red rice and otherweeds. Water management in this system iscritical, and breakdowns in control usuallyresult from inadequate flood maintenance.

Although Bolero and Ordram suppressred rice, they do not provide completecontrol. Using these herbicides incombination with water management,however, can minimize interference fromred rice. Rotating rice with soybeans orother crops and controlling red rice witheffective herbicides are important inmanaging red rice.

Summary. Numerous herbicides andtank mixtures of herbicides are available foruse in rice, and, with the exception of redrice, adequate weed control can beobtained when these herbicides are appliedin a timely manner coupled withappropriate water management. Early-season weed interference can be verydetrimental and can reduce yields eventhough control practices are implementedlater. Failure to apply herbicides in a timelymanner may result in poor weed controland the need for repeat applications. Thesesituations allow more early-season weedcompetition and generally less effectivecontrol.

Before using a herbicide, follow alldirections and precautions. In addition tobeing illegal, failure to follow the label canresult in poor weed control, excessive riceinjury and environmental and safetyhazards.

Herbicide OptionsHerbicides in these tables have been

evaluated by Louisiana AgriculturalExperiment Station researchers under avariety of environmental conditions.Recommendations and ratings reflect theaverage expected performance used inaccordance with label specifications. Theefficacy of these herbicides on importantrice weed species is presented in Tables 7and 8. Specific recommendations forherbicide use are in Table 9.

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Table 7. Weed response to preplant and preemergence burndown herbicides. 1. Poor (P) = lessTable 7. Weed response to preplant and preemergence burndown herbicides. 1. Poor (P) = lessTable 7. Weed response to preplant and preemergence burndown herbicides. 1. Poor (P) = lessTable 7. Weed response to preplant and preemergence burndown herbicides. 1. Poor (P) = lessTable 7. Weed response to preplant and preemergence burndown herbicides. 1. Poor (P) = lessthan 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = not rated.than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = not rated.than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = not rated.than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = not rated.than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = not rated.

Gramoxone Extra E P-F G E E E E P F F F G E E P P

Gramoxone Extra E F G E E E E F G E G E E E F-G E+ Harmony Extra

Gramoxone Extra E P G E E E E G E G F G E E G G+ 2,4-D

Roundup Ultra E F-G E E E G E F F G E E E E G G

Roundup Ulta E F-G E E E G E E G E E E E E E E+ Harmony Extra

Roundup Ultra E F-G E E E E E G E G E E E E G G+ 2,4-D

2,4-D P P P P E G P G E P F G E G F F

1.Burndown herbicides control only emerged weeds. A residual herbicide can be tank-mixed to extend the weed control. Follow label directions.

Ann

ual

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ss

Ann

ual

Rye

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Car

olin

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ley

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Car

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ning

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dw

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ards

pur

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4343434343

Table 8. Weed response to in-season herbicides and herbicide combinations. Poor (P) =Table 8. Weed response to in-season herbicides and herbicide combinations. Poor (P) =Table 8. Weed response to in-season herbicides and herbicide combinations. Poor (P) =Table 8. Weed response to in-season herbicides and herbicide combinations. Poor (P) =Table 8. Weed response to in-season herbicides and herbicide combinations. Poor (P) =less than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = notless than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = notless than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = notless than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = notless than 49%, Fair (F) = 50-69%, Good (G) = 70-89%, Excellent (E) = 90-100%, “-” = notrated.rated.rated.rated.rated.

PREPLANTBURNDOWNRoundup Ultra F G E F-G E E F F G E F - E E E2,4-D1 E E P P P P P-F G-E E E E E E E EGramoxone Extra F G G-E G G G F-G P G E G - E G F-G

PREEMERGENCEBolero (PPS)2. P G G G3. G F E P E G F E F E POrdram (PPS)2. F P E G3. - F E P P P P P P P PBolero (Delayed)2. P P G P G F - P E E P E P E PFacet E - E P P E P P P P G P - - PProwl (Delayed)4. P P G P G G P P P P P P P P P

POSTEMERGENCEArrosolo G G E P E5. E E6. P G5. G5. E - G5. G5. EPropanil F G E P E5. E E6. P G5. G5. E - G5. G5. GOrdram2. P P G P - P G P P P P P P P PGrandstand E G-E P P P P F G-E P G G P-F E G G2,4-D Amine E E P P P P P6. G E E E E G E EBlazer F F P P P P P P - - E - P - FBasagran F G P P P P E P F E F G P E PProwl + Propanil F-G G E P E5. E E6. P G5. G5. E - G5. G5. GFacet5. E G E P P E P F P P G - G - FBolero2. + Propanil G G E P E E E P G5. G5. E - G5. G5. GLondax G G P P P P E F E E P E P G GFacet + Propanil E G E P E5. E E6. F G5. G5. E - G5. G5. ELondax + Propanil E E E P E5. E E F E E E E G5. G5. EGranstand + Propanil E E E P E5. E E G-E G E E - E G GGranstand + Arrosolo E E E P E E E E G E E - E G EGranstand + Facet E E E P P E F E P E G F E G G

1.2,4-D labels differ in the length of time required between applications and planting.

2.See label for variety susceptibility.

3.With proper water management.

4.Drill-seeded rice after susceptibility.

5.Controlled only when small (less than 2 leaves).

6.A few sedges are controlled.

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Ecl

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Red

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Red

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Hem

p S

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Wat

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Tex

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4444444444

Table 9. Recommended herbicides, application methods and rates, and commentsTable 9. Recommended herbicides, application methods and rates, and commentsTable 9. Recommended herbicides, application methods and rates, and commentsTable 9. Recommended herbicides, application methods and rates, and commentsTable 9. Recommended herbicides, application methods and rates, and commentsconcerning use in rice in Louisiana.concerning use in rice in Louisiana.concerning use in rice in Louisiana.concerning use in rice in Louisiana.concerning use in rice in Louisiana.

.

4545454545

4646464646

4747474747

4848484848

.

4949494949

5050505050

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5151515151

Disease ManagementDisease ManagementDisease ManagementDisease ManagementDisease ManagementDonald E. Groth, Milton C. Rush andClayton A. Hollier

IntroductionDisease damage to rice can greatly

impair productivity and sometimes destroya crop. The United States does not haveany of the destructive viral diseasespresent in other rice-growing areas of theworld, but fungal diseases are prevalentand very destructive to Louisiana rice.Several bacterial diseases have beenfound, but no significant yield losses havebeen associated with them.

Direct losses to disease include reduc-tion in plant stands, lodging, spottedkernels, fewer and smaller grains perplant, and a general reduction in plantefficiency. Indirect losses include the costof fungicides used to manage disease,application costs and reduced yields

associated with special cultural practicesthat reduce disease, but may not be condu-cive to producing maximum yields.

The major diseases of rice in the UnitedStates are the fungal diseases blast, causedby Pyricularia grisea (Figs. 54-57); stemrot, caused by Magnaporthe salvinii (Scle-rotium oryzae) (Figs. 58, 59); sheathblight, caused by Thanatephoruscucumeris (Rhizoctonia solani) (Figs. 60-63); brown spot, caused by Cochiobolusmiyabeanus (Fig. 64); narrow brown spot,caused by Sphaerulina oryzina(Cercospora janseana) (Figs. 65, 66); andkernel smut, caused by Neovossia horrida(Fig. 67). Seedling diseases caused byspecies of Achlya and Pythium (Figs. 68,69) also are important in water-seededrice.

Minor diseases include crown rot (Fig.70), causal agent unknown; leaf scald,caused by Gerlachia oryzae (Figs. 71, 73);

5252525252

leaf smut, caused by Entyloma oryzae(Fig. 73); sheath rot, caused bySarocladium oryzae (Fig. 74); stackburndisease, caused by Alternaria padwickii(Fig. 75); sheath spot, caused by Rhizocto-nia oryzae (Figs. 76,77); crown sheath rot,caused by Gaeumannomyces graminis var.graminis (Fig. 78); black kernel, caused byCurvularia lunata; seedling blights, causedby various fungi (Fig. 79); bacterial leafblight (Fig. 80); false smut, caused byUstilaginoidea virens (Fig. 81); root rots,caused by several fungi; and severalmiscellaneous leaf,stem and glumespotting diseases.Several diseasescaused by sclero-tial fungi are alsofound in Louisianabut are not signifi-cant.

A disorderknown as panicleblight (Fig. 82) hasbecome increasingly important. Little isknown about its cause.

An undefined pathogen complex actingalone or with insect damage (feeding) alsocauses the grain and kernel discolorationcalled “pecky” rice (Fig. 108).

The physiological disorders straighthead(Fig. 83) and bronzing or zinc deficiency(Fig. 32) occur throughout the southern ricearea and are locally severe. Cold injury(Fig. 84), salt damage (Fig. 85) and nutrientdeficiencies often mimic disease symptoms.

Two minor diseases of rice in Louisianaare caused by small parasitic round wormscalled nematodes. These are white tip,caused by Aphelenchoides besseyi (Fig. 86),and root knot, caused by Meloidogynespecies (Fig. 87).

The first step toward diseasemanagement is identification followed bycareful field scouting. Diseases known tooccur in Louisiana and their causal agentsare listed in Table 10. A guide for rapididentification of the major diseases is givenin the following section (Table 11).Knowing the level of resistance of thevariety to major diseases can be useful in

determining the probability of havingproblems warranting preventivemanagement measures. Commercialvarieties and their resistance levels tomajor diseases are in Table 12. Scoutinginformation or disease thresholds andmanagement information are summarizedfor the major diseases in Table 13.

Use of foliar fungicides to manage ricediseases is often justified under severedisease conditions. Some factors whichaffect the probability of fungicide usebeing warranted include disease history in

the field, theresistance of thevariety, the yieldpotential, use (seedor grain), date ofplanting and ratooncrop potential.Always followlabel directions.Since the list oflabeled fungicidesmay change,

contact your Cooperative ExtensionService agent for current information onfungicides available for rice diseasemanagement.

Rice Disease IdentificationEach year the Louisiana rice crop is

affected by many diseases. Severity ofsymptoms often varies because of varietalresistance, environmental conditions andplant growth stage. Also, not allsymptoms typical of a disease occur on asingle plant. It is important to look atseveral plants, from all over the field, toestablish an accurate diagnosis. In thetext, all symptoms known to occur aredescribed, but not all will be expressed.Use the guide to the identification of ricediseases present in Louisiana to decidewhich diseases are present. The diseasesare divided into sections based on whatplant part is affected. Several diseasesmay affect more than one part of a riceplant, however. When a disease isidentified, more information is in the textand in Table 13.

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Table 10. Rice diseases and disorders in Louisiana.Table 10. Rice diseases and disorders in Louisiana.Table 10. Rice diseases and disorders in Louisiana.Table 10. Rice diseases and disorders in Louisiana.Table 10. Rice diseases and disorders in Louisiana.

Common NameCommon NameCommon NameCommon NameCommon Name Pathogen name or causePathogen name or causePathogen name or causePathogen name or causePathogen name or cause

Bacterial diseases

Bacterial blight Xanthomonas oryzae pv. oryzae (Ishiyama) Swings et al.= X. campestris pv. oryzae (Ishiyama) Dye

Foot rot Erwinia chrysanthemi Burkholder et al.

Pecky rice (kernel spotting) Damage by bacteria (see also under fungal andmiscellaneous diseases)

Fungal diseases

Black kernel Curvularia lunata (Wakk.) Boedijn(teleomorph: Cochiobolus lunatus R.R. Nelson & Haasis)

Blast (leaf, neck [rotten neck],nodal and collar) Pyricularia grisea Sacc.=P. oryzae Cavara

(teleomorph: Magnaporthe grisea (Hebert) Barr)

Brown spot Cochliobolus miyabeanus (Ito & Kuribayashi) Drechs.ex Dastur (anamorph: Bipolaris oryzae(Breda de Haan) Shoemaker)

Crown sheath rot Gaeumannomyces graminis (Sacc.) Arx & D. Olivier

Downy mildew Sclerophthora macrospora (Sacc.) Thirumalachar et al.

Eyespot Drechslera gigantea (Heald & F.A. Wolf) Ito

False smut Ustilaginoidea virens (Cooke) Takah.

Kernel smut Tilletia barclayana (Bref.) Sacc. & Syd. in Sacc.= Neovossia horrida (Takah.) Padwick & A. Khan

Leaf smut Entyloma oryzae Syd. & P. Syd.

Leaf scald Microdochium oryzae (Hashioka & Yokogi) Samuels& I.C. Hallett= Rhynchosporium oryzae Hashioka & Yokogi

Narrow brown leaf spot Cercospora janseana (Racib.) O. Const.= C. oryzae Miyake(teleomorph: Sphaerulina oryzina K. Hara)

Pecky rice (kernel spotting) Damage by many fungi including Cochliobolusmiyabeanus (Ito & Kuribayashi) Drechs. ex Dastur,Curvularia spp., Fusarium spp., Microdochium oryzae(Hashioka & Yokogi) Samuels & I.C. Halett,

5454545454

Sarocladium oryzae (Sawada) W. Gams & D.Hawksworth and other fungi

Root rots Fusarium spp., Pythium spp., P. dissotocum Drechs.,P. spinosum Sawada

Seedling blight Cochliobolus miyabeanus (Ito & Kuribayashi) Drechs.ex Dastur, Curvularia spp., Fusarium spp.,Rhizoctonia solani Kuhn, Sclerotium rolfsii Sacc.(teleomorph: Athelia rolfsii (Curzi) Tu & Kimbrough),and other pathogenic fungi.

Sheath blight Thanatephorus cucumeris (A.B. Frank) Donk(anamorph: Rhizoctonia solani Kuhn)

Sheath rot Sarocladium oryzae (Sawada) W. Gams & D.Hawksworth= Acrocylindrium oryzae Sawada

Sheath spot Rhizoctonia oryzae Ryker & Gooch

Stackburn (Alternaria Alternaria padwickii (Ganguly) M.B. Ellisleaf spot)

Stem rot Magnaporthe salvinii (Cattaneo) R. Krause & Webster(synanamorphs: Sclerotium oryzae Cattaneo, Nakataeasigmoidae (Cavara) K. Hara)

Water-mold (seed-rot and seedling disease) Achlya conspicua Coker, A. klebsiana Pieters, Fusarium

spp., Pythium spp., P. dissotocum Drechs., P. spinosumSawada

Disorders

Bronzing Zinc deficiency

Cold injury Low temperatures

Panicle blight Cause undetermined

Pecky rice (kernel spotting) Feeding injury by rice stink bug

Straighthead Arsenic induced, unknown physiological disorder

Nematodes

Root-knot Meloidogyne spp.

White tip Aphelenchoides besseyi Christie

5555555555

F I G U R E S

5 65 65 65 65 6

5757575757

Figure 1. Germination

Figure 2. Coleoptile and radicle development

Figure 3. Mesocotyl development

Figure 4. Primary leaf

Figure 5. Primary leaf elongates

Figure 6. Sheath, collar and blade

Figure 7. First leaf

Figure 8. Second leaf

5 85 85 85 85 8

Figure 9. Shoot and root parts

Figure 10. First primary tiller

Figure 11. Second primary tiller

Figure 12. Crown and modes

Figure 13. Green ring

Figure 14. Second internode Figure 15. Panicle differentiation

5959595959

Figure 16. Early boot

Figure 17. Late boot

Figure 18. First heading

Figure 19. Full heading/pollination

Figure 20. Milk stage

Figure 21. Dough stage

Figure 22. Firm endosperm

6 06 06 06 06 0

Figure 23. Harvest maturity

Figure 26. Nitrogen deficient rice

Figure 27. Nitrogen deficient rice Figure 28. Nitrogen deficient rice

Figure 29. Straighthead

Figure 30. Phosphorus deficiencyFigure 31. Potassium deficiency

Figure 32. Zinc deficiency

6161616161

Figure 33. Seedling barnyardgrass

Figure 34. Barnyardgrass

Figure 35. Broadleaf signalgrass

Figure 36. Red rice

Figure 37. Hemp sesbania

Figure 38. Hemp sesbania

Figure 39. Alligatorweed

Figure 40. Dayflower

6 26 26 26 26 2

Figure 41. Ducksalad Figure 42. Jointvetch Figure 43. Perennial sedges

Figure 44. Perennial sedges

Figure 45. Perennial sedges

Figure 46. Red pericarp of red rice

Figure 47. Water bermuda

Figure 48. Sprangletop

Figure 49. Morningglories

6363636363

Figure 50. Texas weed seedling

Figure 51. Texas weed seedling

Figure 52. Eclipta

Figure 53. Smartweed

Figure 54. Leaf blast

Figure 55. Node blast

Figure 56. Collar blast

Figure 57. Rotten neck blastFigure 58. Stem rot

Figure 59. Stem rot

Figure 60. Sheath blight (early lesion)

6 46 46 46 46 4

Figure 61. Sheath blight (sclerotia) Figure 62. Sheath blight Figure 63. Sheath blight (leaf lesion)

Figure 64. Brown spot Figure 65. Narrow brown spot (leaf)

Figure 66. Narrow brown spot (sheath)

Figure 67. Kernel smutFigure 68. Water molds Figure 69. Water molds

Figure 70. Crown rot Figure 71. Leaf scald

6565656565

Figure 72. Leaf scald

Figure 73. Leaf smut

Figure 74. Sheath rot

Figure 75. Stackburn

Figure 76. Sheath spot Figure 77. Sheath spot

Figure 78. Crown sheath rot

Figure 79. Seedling blight

Figure 80. Bacterial leaf blight Figure 81. False smut

6 66 66 66 66 6

Figure 82. Panicle blight

Figure 83. Straighthead Figure 84. Cold injury

Figure 85. Salt injury

Figure 86. White tip

Figure 87. Root knot

Figure 88. Downy mildew

Figure 89. Seed midge tubes

6767676767

Figure 90. Seed midge damage

Figure 91. Chinch bugs

Figure 92. Rice leaf miner larva

Figure 93. Leaf miner damage

Figure 94. Leaf miner stand reduction

Figure 95. Adult rice water weevils

Figure 96. Rice water weevil larva on roots

Figure 97. Rice water weevil pupa

Figure 98. Rice water weevil leaf scars

Figure 99. Water weevil damage (pruned roots)

Figure 100. Water weevil sampling bucket

Figure 101. Rice stem borer adult

6 86 86 86 86 8

Figure 102. Rice stem borer larva Figure 103. Sugarcane borer larva on rice

Figure 104. Stalkborer injury Figure 105. Stalkborer (white-headcondition)

Figure 106. Rice stink bug adult

Figure 107. Rice stink bug adult

Figure 108. Pecky rice

Figure 109. Skipper larva

Figure 110. Skipper adult

6969696969

Table 11. A guide to the identification of rice diseases present inTable 11. A guide to the identification of rice diseases present inTable 11. A guide to the identification of rice diseases present inTable 11. A guide to the identification of rice diseases present inTable 11. A guide to the identification of rice diseases present inLouisianaLouisianaLouisianaLouisianaLouisiana

For identification of the major diseases, determine the part of the plant affectedby the disease then refer to that section of Table 11. A list of the causal agents ofall rice diseases known to occur in Louisiana is in Table 10.

I. Planted Seeds and SeedlingsI. Planted Seeds and SeedlingsI. Planted Seeds and SeedlingsI. Planted Seeds and SeedlingsI. Planted Seeds and SeedlingsWater-seeded rice: seeds rotted after draining water from field, copper or

greenish-brown spots on soil surfaces around or above rotted seeds; coarse, bristlymycelium radiating from seed (Achlya spp.) (Fig. 68) or gelatinous matrixsurrounding each affected seed (Pythium spp.) (Fig. 69). Water Mold.

Water-seeded rice: seedlings 1 to 4 inches tall dying in seedling flood or afterflushing seeded field. Pythium Seedling Blight.

Drill-seeded or dry broadcast rice: seedlings 1 to 4 inches tall dying:a) Brown spot on coleoptile or growing point (Fig. 79), seedlings suddenly dying.

Seedling Blight.b) Seedlings dying or turning white in patches or in short strips of drill row; fluffy

white mycelium and small, round sclerotia (tan) may be present on soil surfaceat the base of affected seedlings after flushing seeded field. Sclerotium Seed-ling Blight.

Seedlings at three- to five-leaf stage dying, often in patches, may have linearreddish-brown lesion on sheath of small seedlings, older seedlings with purple-brown blotches made up of small spots aggregating, leaves yellow or bronze (Fig.32), lower leaves floating on surface of flood water, seedlings dying in deeperwater and disappearing below surface of water. Bronzing.

See also Salinity and Cold Injury.

II. Roots and Crown (Root-Stem Interface)II. Roots and Crown (Root-Stem Interface)II. Roots and Crown (Root-Stem Interface)II. Roots and Crown (Root-Stem Interface)II. Roots and Crown (Root-Stem Interface)Crown area decayed with soft rot, black or dark brown with streaks extending

to the lower internodes of culms (Fig. 70), fetid odor of bacterial soft rot, tillersdying one at a time; roots dying and turning black, adventitious roots produced atnode above crown area. A similar discoloration of the crown may be caused byapplying hormonal herbicide such as 2,4-D too early. Crown Rot.

Roots turning black or brown, decayed, reduced root volume, roots dying. RootRot.

Roots with swollen areas, found only under dry-land conditions (Fig. 87). Rootknot.

III. Leaf BladesIII. Leaf BladesIII. Leaf BladesIII. Leaf BladesIII. Leaf BladesLesions varying from small round, dark-brown spots, to oval spots with narrow

reddish-brown margin and gray or white center with dark circular line (eyespotlesion) (Fig. 54), spots becoming elongated, diamond-shaped or linear with graydead area in center surrounded by narrow reddish-brown margin. Leaf Blast.

Round to oval, dark-brown lesions with yellow or gold halo (Fig. 64); as lesionsenlarge, they remain round, with center area necrotic, gray and lesion marginreddish-brown to dark brown. Brown Spot.

7070707070

Long, narrow brown or reddish-brown lesion (Fig. 65); lesions 0.5 to 3 cm long,parallel with leaf veins, and usually restricted to the area between veins; lesionsmay occur on leaf sheaths. Narrow Brown Leaf Spot.

Lesions consist of alternating wide bands of white, greenish-gray or tan withnarrow bands of reddish-brown or brown (Fig. 63); lesions begin at base of blade,spreading from leaf sheath or from infection point on leaf blade. Sheath Blight.

Lesions consist of wide bands of gray, dying tissue alternating with narrowreddish-brown bands (Fig. 71); band pattern in chevrons from leaf tip or edges ofthe leaf, sometimes lesions are gray blotches at leaf edge with reddish-brownmargin, advancing edge of lesion usually has a yellow or gold area (Fig. 72)between reddish-brown margin and green, healthy tissues. Leaf Scald.

Small 1-2 mm, black linear lesions on leaf blade (Fig. 73), usually more lesions onupper half of the leaf blade, lesions may have dark gold or light brown halo, leaf tipdries as plants approach maturity, lesions on sheaths of upper leaves. Leaf Smut.

Round or oval white or pale tan spot with narrow red or reddish-brown margin(Fig. 75); often two adjacent spots coalesce to form an oval double spot; lesions arefrom 0.5 to 1 cm in diameter, spots with small black fruiting structures in the center.Stackburn.

Leaf tips turn white with a yellow area between the white tip and the healthygreen area (Fig. 86); white areas sometimes occur on leaf edges; flag leaf bladetwisted with poor emergence of the panicle; kernels aborted or poorly filled; graindistorted or discolored. White Tip.

Lesions consist of elongated lesions near the leaf tip or margin and start out watersoaked in appearance; lesions, several inches long, turn white to yellow and thengray because of saprophytic fungi (Fig. 80). Bacterial Leaf Blight.

IVIVIVIVIV. Leaf Sheath and Stem. Leaf Sheath and Stem. Leaf Sheath and Stem. Leaf Sheath and Stem. Leaf Sheath and StemWater-soaked, gray-green lesion at water line (Fig. 60) during tillering or early

jointing stages of growth, lesions becoming oval, white or straw-colored in centerwith reddish-brown edge (Fig. 62), lesions 1 - 2 cm wide and 3 - 4 cm long, lesionsspreading up leaf sheaths and onto leaf blades, lesions discrete or forming acontinuous band on sheath (Fig. 62) or leaf (Fig. 63) of alternating wide necroticareas with narrow reddish-brown bands. Sheath Blight.

Black, angular lesions on leaf sheaths at water line on plants at tillering or earlyjointing stages of growth (Fig. 58); at later stages outer sheath drying, inner sheathdiscolored or with black angular lesion; culms discolored with dark-brown or blackstreaks; raised areas of dark fungus mycelium on surface; gray mycelium inside ofculm or at maturity culm collapsed with small, round black sclerotia in dead sheathtissues and inside of culm (Fig. 59). Stem Rot.

Lesions oval, pale green, turning cream or white in the center with a broad darkreddish-brown margin (Fig. 76, 77). Lesions remain separate, not forming largecontinuous lesions. Sheath Spot.

7171717171

Black to brown diffuse lesions on the sheath near the water line (Fig. 78).Perithecia necks protruding from upper surface and a thick fungal mat between leafsheath and culm. Crown Sheath Rot.

Reddish- or purple-brown, netlike pattern on sheath below the collar of lowerleaf blades (Fig. 66), lesion oval, 1 to 2 cm wide and 3 to 5 cm long, leaf bladesturning yellow and drying. Cercospora Net Spot. (See Narrow Brown Leaf Spot.)

General reddish discoloration of flag leaf sheath or reddish-brown or yellow-tanspots with dark, irregular ring pattern inside of spots (Fig. 74); panicles emergingpoorly; stem of panicle twisted; white “frosting” of conidia on inside of leaf sheath,florets of panicles on affected tillers discolored a uniform reddish-brown or darkbrown. Grain does not fill or kernels are lightweight. Sheath Rot.

Narrow red-brown lesions on flag leaf sheath or penultimate leaf sheath afterpanicles emerge; lesions 0.5 to 1.5 mm wide and up to 1 to 3 cm long; lesions runparallel with veins in sheaths, affecting the tissues between veins (Fig. 66). NarrowBrown Leaf Spot.

Collar of flag leaf discolored brown or chocolate-brown; leaf blade detaches fromsheath as lesion dies and dries (Fig. 56). Blast on Flag Leaf Collar.

Culm nodes turn black or nodes become shriveled and gray as plants approachmaturity (Fig. 55); nodes purple to blue-gray with conidia of the pathogen; culmsand leaves straw-colored above affected node; culms lodge at affected nodes. NodeBlast.

VVVVV. Panicle, Florets and Grain. Panicle, Florets and Grain. Panicle, Florets and Grain. Panicle, Florets and Grain. Panicle, Florets and GrainPaniclePaniclePaniclePaniclePanicle

Node and surrounding area at base of panicle discolored brown or chocolate-brown (Fig. 57); stem of panicle shrivels and may break; node purplish or blue-graywith conidia of the fungal pathogen; panicle white or gray; florets do not fill andturn gray; panicle branches and stems of florets gray-brown lesions. Rotten NeckBlast.

Panicles upright, not falling over or slightly bent over because of sterility. Hullsdistorted, beak-shaped. Plants may not head at all (Fig. 83). Straighthead.

Internodal area above or below node at the base of the panicle turns light brownor tan-brown; affected area dies and shrivels; kernels in florets of lower portion ofthe panicle do not fill. Neck Blight. (See Brown Spot and Narrow Brown Leaf Spotfor more information.)

Single florets or several florets on a panicle branch turn light brown or straw-colored; floret stem with brown lesion; grain stops developing; florets turn gray.Panicle Blast.

Panicles irregular, unable to emerge from the leaf sheath, and becoming twisted(Fig. 88); the panicle is small, normally remaining green longer than usual; no seedsproduced. Downy Mildew.

7272727272

Panicles small, reduced number of spikelets, and lemmas and paleas oftenabsent on terminal portions of panicles. White Tip.

Florets and GrainSingle florets or several florets per panicle with brown, reddish-brown, purple or

white surrounded by purple-brown spots (Fig. 108). Grain Spotting or PeckyRice.

Maturing grain partially filled with or without grayish cast; powdery black masson surface of the kernel and at seam between palea and lemma (Fig. 67) (rubs offeasily onto fingers). Kernel Smut. See black kernel.

Single florets or more commonly several florets in a panicle turn reddish-brownto dark brown. Sheath Rot.

Single florets or several florets on a panicle branch turn light brown or straw-colored (Fig. 82). The grain stops developing, and the florets turn gray. PanicleBlight.

Maturing grain partially filled, shriveled, chalky, fuzzy black mass coveringsurface of the grain or at seam between palea and lemma (will not easily rub off onfingertips). Brown Spot.

Large orange fruiting structure on one or two grains in maturing panicle; whenorange membrane ruptures, a mass of greenish-black spores is exposed (Fig. 81);grain replaced by one or more sclerotia. False Smut.

Rice Diseases in LouisianaRice Diseases in LouisianaRice Diseases in LouisianaRice Diseases in LouisianaRice Diseases in Louisiana

Bacterial Leaf BlightBacterial leaf blight is caused by the

bacterium Xanthomonas campestris pv.oryzae. It was first identified in the UnitedStates in Texas and Louisiana in 1987. Nomajor losses have been associated withthis disease in the United States, butbacterial leaf blight in other parts of theworld causes severe damage.

The blight bacterium overwinters inrice debris in the soil and on weed hosts.There is also a slight chance that seed maytransmit the pathogen. The pathogen isspread by wind-blown rain, irrigationwater, plant contact and probably on plantdebris on machinery. High humidity andstorms favor disease development. Water-soaked areas appear on the leaf marginsnear the tips, enlarge and turn white toyellow. As the lesions mature, theyexpand, turn white and then gray becauseof growth of saprophytic fungi (Fig. 80).The lesion may be several inches long.

Contact your Cooperative ExtensionService agent if you suspect this disease.Accurate identification is important sincethe symptoms can be confused with otherdiseases, especially leaf scald, herbicidedamage and other plant stress.

Management practices include rotatingto nongrass crops, tilling to destroy plantdebris and avoiding contaminating the fieldthrough infected plant materials orirrigation water.

Black KernelThe fungus Curvularia lunata causes

black kernel. The fungus causes severegrain discoloration, and after milling thekernels appear black. When infections areheavy, the fungus can cause seedlingblights or weakened seedlings. Thisdisease is rarely severe enough thatmanagement practices are recommended.Seed treatments to manage other diseasesshould reduce seedling damage. No othermanagement measures are warranted.

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BlastBlastBlastBlastBlastRice blast is caused by the fungus

Pyricularia grisea. The disease is alsocalled leaf blast, node blast, panicle blast,collar blast and rotten neck blast,depending on the portion of the plantaffected. Blast has been one of the mostimportant diseases in Louisiana, causingsevere yield losses to susceptible varietiesunder favorable environmental conditions.

Blast can be found on the rice plantfrom the seedling stage to near maturity.The leaf blast phase occurs between theseedling and late tillering stages. Spots onleaves start as small white, gray or bluetinged spots, which enlarge quickly undermoist conditions to either oval diamond-shaped spots or linear lesions with pointedends with gray or white centers andnarrow brown borders (Fig. 54). Leavesand whole plants are often killed undersevere conditions. Lesions on resistantplants are small brown specks that do notenlarge.

On stem nodes (Fig. 55), the host tissueturns black and becomes shriveled andgray as the plant approaches maturity. Theinfected area may turn dark purple toblue-gray because of the production offungal spores. Culms and leaves becomestraw-colored above the infected node.Plants lodge or break off at the infectedpoint, or they are connected only by a fewvascular strands. Some varieties areinfected where the flag leaf attaches to thesheath at the collar (Fig. 56). The lesionturns brown or chocolate brown to gray,and the flag leaf becomes detached fromthe plant as the lesion area becomes deadand dry.

Rotten neck symptoms appear at thebase of the panicle starting at the node(Fig. 57). The tissue turns brown to choco-late brown and shrivels, causing the stemto snap and lodge. If the panicle does notfall off, it may turn white to gray, or theflorets that do not fill will turn gray.Panicle branches and stems of florets alsohave gray-brown lesions.

Scouting a field for blast should beginearly in the season during the vegetativephase and continue through the season toheading. Leaf blast will usually appear in

the high areas of the field where the floodhas been lost or is shallow. Areas of heavynitrogen fertilization and edges of thefields are also potential sites of infection.If leaf blast is in the field or has beenreported in the same general area, and ifthe variety is susceptible, fungicidalapplications are advisable to reduce rottenneck blast.

The pathogen overwinters as myceliumand spores on infected straw and seed.Spores are produced from specializedmycelium called conidiophores and be-come windborne at night on dew or rain.The spores are carried by air currents andland on healthy rice plants. The sporesgerminate under high humidity and dewconditions and infect the plant. Generallylesions will appear four to seven dayslater, and additional spores are produced.Plants of all ages are susceptible. Mediumgrain varieties are more susceptible toblast, especially during the leaf phase,than the long grain varieties grown inLouisiana.

Environmental conditions that favordisease development are long dew peri-ods, high relative humidity and warm dayswith cool nights. Agronomic practices thatfavor disease development include exces-sive nitrogen levels, late planting and drysoil (loss of flood). Several physiologicraces of P. grisea exist, and disease devel-opment varies, depending on variety-raceinteractions.

The disease can be reduced by plantingresistant varieties (Table 12), maintaining a4- to 6-inch flood (Kim, 1986), propernitrogen fertilizer, avoiding late plantingand by applying a fungicide recommendedby the Louisiana Cooperative ExtensionService.

Brown SpotBrown spot, caused by the fungus

Cochiobolus miyabeanus, is one of themost prevalent rice diseases in Louisiana.It is also called Helminthosporium leafspot. When C. miyabeanus attacks theplants at emergence, the resulting seedlingblight causes sparse or inadequate standsand weakened plants. Leaf spots arepresent on young rice, but the disease is

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more prevalent as the plants approachmaturity and the leaves begin to senesce.Yield losses from leaf infection or leafspots are probably not serious. When thefungus attacks the panicle, including thegrain, economic losses occur. Heavy leafspotting indicates an unfavorable growthfactor, usually a soil problem.

The pathogen also attacks thecoleoptiles, leaves, leaf sheath, branchesof the panicle, glumes and grains. Thefungus causes brown, circular to oval spotson the coleoptile leaves of the seedlings(Fig. 79). It may cause seedling blight.

Leaf spots are found throughout theseason. On young leaves, the spots aresmaller than those on older leaves. Thespots may vary in size and shape fromminute dark spots to large oval to circularspots (Fig. 64). The smaller spots are darkbrown to reddish-brown. The larger spotshave a dark brown margin and a light,reddish-brown or gray center. The spotson the leaf sheath and hulls are similar tothose on the leaves.

The fungus attacks the glumes andcauses a general black discoloration. It alsoattacks the immature florets, resulting in nograin development or kernels that arelightweight or chalky.

Brown spot is an indicator ofunfavorable growth conditions includinginsufficient nitrogen, inability of the plantsto use nitrogen because of rice water-weevil injury, root rot or other unfavorablesoil conditions. As the plants approachmaturity, brown spot becomes moreprevalent, and the spots are larger onsenescing leaves.

Damage from brown spot can bereduced by maintaining good growingconditions for rice by proper fertilization,crop rotation, land leveling, proper soilpreparation and water management. Seed-protectant fungicides reduce the severityof seedling blight caused by thisseedborne fungus. Some varieties are lesssusceptible than others (Table 12).

Crown RotCrown rot is suspected to be caused by

a bacterial infection (possibly Erwiniachrysanthemi). It is a minor disease

usually associated with the variety Saturn.Symptoms first appear during tillering. Thecrown area is decayed, with soft rotting,becoming black or dark brown withdiscolored streaks extending into the lowerinternodes of culms (Fig. 70). There is afetid or putrid odor characteristic ofbacterial soft rots, and tillers start dyingone at a time. The roots also die and turnblack. Adventitious roots are produced atthe node above the crown area. A similardiscoloration of the crown can be causedby misapplied herbicides. Control practicesare not available.

Crown Sheath RotCrown sheath rot is caused by the

fungus Gaeumannomyces graminis var.graminis. Other names for this diseaseinclude brown sheath rot, Arkansas foot rotand black sheath rot. It has beenconsidered a minor disease of rice, butrecent reports from Texas suggest severedamage can occur. The pathogen killslower leaves, thus reducing photosyntheticactivity, causes incomplete grain fillingand plants can lodge.

Symptoms appear late in the season,usually after heading. Sheaths on the lowerpart of the rice plant are discolored brownto black (Fig. 78). Reddish-brown mycelialmats are found on the inside of infectedsheaths. Dark perithecia are producedwithin the outside surface of the sheath.Perithecia are embedded in the sheathtissues with beaks protruding through theepidermis. This disease can easily beconfused with stem rot (Fig. 58).

The fungus survives as perithecia andmycelia in plant residues. Ascospores arewindborne in moist conditions. The fungushas been reported to be seedborne.Management practices have not beenworked out for this disease.

Downy MildewDowny mildew is caused by the fungus

Sclerophthora macrospora. In early growthstages, infected seedlings are dwarfed andtwisted with chlorotic, yellow to whitishspots. Symptoms are more severe on thehead (Fig. 88). Because of failure toemerge, panicles are distorted, causing

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irregular, twisted and spiral heads thatremain green longer than normal. Nocontrol measures are recommended.

False SmutFalse smut, caused by the fungus

Ustilaginoidea virens, is a minor disease inthe United States. The disease ischaracterized by large orange to brown-green fruiting structures on one or moregrains of the mature panicle (Fig. 81).When the orange covering ruptures, amass of greenish-black spores is exposed.The grain is replaced by one or moresclerotia. All varieties appear to have ahigh level of resistance, and diseasecontrol measures are not required.

Grain Spotting and Pecky RiceMany fungi infect developing grain and

cause spots and discoloration on the hullsor kernels. Damage by the rice stink bug,Oebalus pugnax F., also causesdiscoloration of the kernel. Kernelsdiscolored by fungal infections or insectdamage are commonly called pecky rice(Fig. 108). This is complex disorderinvolves many fungi, the white-tipnematode and insect damage. High windsat the early heading stage may causesimilar symptoms. Proper insect controland disease management will reduce thisproblem.

Kernel SmutThis fungal disease is caused by

Neovossia barclayana. Symptoms areobserved at or shortly before maturity. Ablack mass of smut spores replaces all orpart of the endosperm of the grain. Thedisease is easily observed in the morningwhen dew is absorbed by the smut spores.The spore mass expands and pushes outof the hull, where it is visible as a blackmass (Fig. 67). When this spore massdries, it is powdery and comes off easilyon fingers. Rain washes the black sporesover adjacent parts of the panicle.Affected grains are a lighter, slightlygrayish color compared with normal grain.

Usually only a few florets may beaffected in a panicle, but fields have beenobserved in Louisiana with 20 percent to

40 percent of the florets affected on 10percent or more of the panicles in a field.Smutted grains produce kernels with blackstreaks or dark areas. Milled rice has a dullor grayish appearance when smuttedgrains are present in the sample. Becausefewer kernels break when parboiled riceis milled, kernel smut can be a severeproblem in processed rice. Growers aredocked in price for grain with a highincidence of smut.

This disease is usually minor inLouisiana, but it can become epidemic inlocal areas. Some varieties are moresusceptible and should be avoided wheresmut is a problem. Spores of the fungusare carried on affected seeds andoverwinter in the soil of affected fields.The pathogen attacks immature,developing grain and is more severe whenrains are frequent during flowering.Specific control measures are notavailable.

Leaf ScaldThis disease, caused by Gerlachia

oryzae, is common and sometimes severein Central and South America. It is presentin the southern rice area of the UnitedStates and in Louisiana annually. It affectsleaves, panicles and seedlings. Thepathogen is seedborne and survivesbetween crops on infected seeds. Thedisease usually occurs on maturing leaves.Lesions start on leaf tips or from the edgesof leaf blades. The lesions have a chevronpattern of light (tan) and darker reddish-brown areas (Fig. 71). The leading edge ofthe lesion usually is yellow to gold (Fig.72). Fields look yellow or gold. Lesionsfrom the edges of leaf blades have anindistinct, mottled pattern. Affected leavesdry and turn straw-colored.

Panicle infestations cause a uniformlight to dark, reddish-brown discolorationof entire florets or hulls of developinggrain. The disease can cause sterility orabortion of developing kernels.

Control measures are notrecommended, but foliar fungicides usedto manage other diseases have activityagainst this disease.

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Leaf SmutLeaf smut, caused by the fungus

Entyloma oryzae, is a widely distributed,but somewhat minor, disease of rice. Thefungus produces slightly raised, blackspots (sori) on both sides of the leaves(Fig. 73) and on sheaths and stalks. Theblackened spots are about 0.5 - 5.0 mmlong and 0.5 - 1.5 mm wide. Many spotscan be found on the same leaf, but theyremain distinct from each other. Heavilyinfected leaves turn yellow, and leaf tipsdie and turn gray. The fungus is spread byairborne spores and overwinters ondiseased leaf debris in soil.

Leaf smut occurs late in the growingseason and causes little or no loss. Controlmeasures are not recommended.

Narrow Brown Leaf SpotNarrow brown leaf spot, caused by the

fungus Cercospora janseana, varies inseverity from year to year and is moresevere as rice plants approach maturity.Leaf spotting may become very severe onthe more susceptible varieties and causessevere leaf necrosis. Some prematureripening, yield reduction and lodgingoccur.

Symptoms include short, linear, brownlesions most commonly found on leafblades (Fig. 65). Symptoms also occur onleaf sheaths, pedicels and glumes. Leaflesions are 2-10 mm long and about 1 mmwide, tend to be narrower, shorter anddarker brown on resistant varieties andwider and lighter brown with gray necroticcenters on susceptible varieties. On upperleaf sheaths, symptoms are similar to thosefound on the leaf. On lower sheaths, thesymptom is similar to a “net blotch” orCercospora sheath spot in which cell wallsare brown and intracellular areas are tan toyellow (Fig. 66).

The primary factors affecting diseasedevelopment are (1) susceptibility ofvarieties to one or more prevalentpathogenic races, (2) prevalence ofpathogenic races on leading varieties and(3) growth stage. Although rice plants aresusceptible at all stages of growth, theplants are more susceptible from panicleemergence to maturity.

Plant breeders have found differencesin susceptibility among rice varieties(Table 12), but resistance is an unreliablecontrol method because new racesdevelop readily. Some fungicides used toreduce other diseases also may haveactivity against narrow brown leaf spot.Low nitrogen levels favors development ofthis disease.

Root KnotSpecies of the nematode Meloidogyne

cause root knot. Symptoms includeenlargement of the roots and the formationof galls or knots (Fig 87). The swollenfemale nematode is in the center of thistissue. Plants are dwarfed, yellow and lackvigor. The disease is rare and yield losseslow. The nematode becomes inactive afterprolonged flooding.

Root RotRoot rots are caused by several fungi

including Pythium spinosum, P.dissotocum, other Pythium spp. andseveral other fungi. The rice plant ispredisposed to this disorder by acombination of factors includingphysiological disorders, insect feeding,especially feeding of rice water weevillarvae, extreme environmental conditionsand various other pathogens.

Symptoms can be noted as early asemergence. Roots show brown to blackdiscoloration and necrosis. As the rootsdecay, nutrient absorption is disrupted, theleaves turn yellow and the plants lackvigor. With heavy root infections, plantslack support from the roots and lodge,causing harvest problems. Often plantswith root rot show severe brown leaf spotinfection. The disease is referred to asfeeder root necrosis when the small fineroots and root hairs are destroyed. Whenthis happens, no lodging occurs andsymptom development is not as apparenton the upper plants.

Fertilizer usually reduces the above-ground symptoms although actual nutrientuse is impaired. Rice water weevil controlgreatly reduces root rots. Draining fieldsstimulates root growth but can cause

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problems with blast, weeds or efficiencyof nutrient use.

Seedling BlightSeedling blight, or damping off, is a

disease complex caused by severalseedborne and soilborne fungi includingspecies of Cochiobolus, Curvularia,Sarocladium, Fusarium, Rhizoctonia andSclerotium. Typically, the rice seedlingsare weakened or killed by the fungi.Environmental conditions are important indisease development. Cold, wet weather isthe most detrimental.

Seedling blight causes stands of rice tobe spotty, irregular and thin. Fungi enterthe young seedlings and either kill orinjure them. Blighted seedlings thatemerge from the soil die soon afteremergence. Those that survive generallylack vigor, are yellow or pale green anddo not compete well with healthyseedlings.

Severity and incidence of seedlingblight depend on three factors: (1)percentage of the seed infested byseedborne fungi, (2) soil temperature and(3) soil moisture content. Seedling blight ismore severe on rice that has been seededearly when the soil is usually cold anddamp. The disadvantages of early seedingcan be partially overcome by seeding at ashallow depth. Conditions that tend todelay seedling emergence favor seedlingblight. Some blight fungi that affect riceseedlings at the time of germination canbe reduced by treating the seed withfungicides.

Seeds that carry blight fungi frequentlyhave spotted or discolored hulls, but seedcan be infected and still appear to beclean. Cochiobolus miyabeanus, one of thechief causes of seedling blight, isseedborne. A seedling attacked by thisfungus has dark areas on the basal parts ofthe first leaf (Fig. 79).

If rice seed is sown early in the season,treating the seed is likely to mean thedifference between getting a satisfactorystand or having to plant a second time.Little benefit is received from treating riceseed to be sown late in the season, unlessunfavorable weather prevails.

The soilborne seedling blight fungus,Sclerotium rolfsii, kills or severely injureslarge numbers of rice seedlings after theyemerge when the weather at emergence ishumid and warm. A cottony white molddevelops on the lower parts of affectedplants. This type of blight can be checkedby flooding the land immediately.

Treatment of the seed with a fungicideis recommended to improve or ensurestands. Proper cultural methods for riceproduction, such as proper planting dateor shallow seeding of early planted rice,will reduce the damage from seedlingblight fungi.

Water- and soil-borne fungi in thegenus Pythium attack and kill seedlingsfrom germination to about the three-leafstage of growth. Infected roots arediscolored brown or black, and the shootsuddenly dies and turns straw-colored.This disease is most common in water-seeded rice, and the injury is often morevisible after the field is drained. It mayalso occur in drill-seeded rice duringprolonged wet, rainy periods.

Seed treatment, planting whentemperatures favor rapid growth ofseedlings and draining the field are thebest management measures for seedlingdisease control.

Sheath BlightSheath blight has been the most

economically significant disease inLouisiana since the early 1970s. Thedisease is caused by Rhizoctonia solani, afungal pathogen of both rice andsoybeans. On soybeans, it causes theaerial blight disease.

Several factors have contributed to thedevelopment of sheath blight from minorto major disease status. They include theincreased acreage planted to susceptiblelong-grain varieties, the increase in theacreage of rice grown in rotation withsoybeans, the increased use of broadcastseeding and the higher rates of nitrogenfertilizers used with the moderncommercial rice varieties. The disease isfavored by dense stands with a heavilydeveloped canopy, high temperature andhigh humidity.

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Sheath blight is characterized by largeoval spots on the leaf sheaths (Fig. 62) andirregular spots on leaf blades (Fig. 63).Infections usually begin during the latetillering-joint elongation stages of growth.The fungus survives between crops asstructures called sclerotia or as hyphae inplant debris. Sclerotia (Fig. 61) or plantdebris floating on the surface of irrigationwater serves as sources of inoculum thatattack and infect lower sheaths of riceplants at the waterline. Lesions about 0.5 -1 cm in width and 1 - 3 cm in length areformed a little above the waterline oninfected culms (Fig. 60). Fungus myceliumgrows up the leaf sheath, forms infectionstructures, infects and causes new lesions.The infection can spread to leaf blades(Fig. 63). The lower leaf sheaths andblades are affected during the jointingstages of growth. After the panicleemerges from the boot, the diseaseprogresses rapidly to the flag leaf onsusceptible varieties. With very susceptiblevarieties, the fungus will spread into theculm from early sheath infections. Infectedculms are weakened, and the tillers maylodge or collapse.

The fungus can spread in the field bygrowing from tiller to tiller on an infectedplant or across the surface of the water toadjacent plants. The fungus also growsacross touching plant parts, for examplefrom leaf to leaf, causing infections onnearby plants. Infected plants are usuallyfound in a circular pattern in the fieldbecause the fungus does not producespores and must grow from plant to plant.

The lesions have grayish-white or lightgreen centers with a brown or reddish-brown margin (Fig. 63). As lesions coalesceon the sheath, the blades turn yellow-orange and eventually die. As areas in thefield with dead tillers and plants increase,they may coalesce with other affectedareas to cause large areas of lodged, deadand dying plants. Damage is usually mostcommon where wind-blown, floating debrisaccumulates in the corners of cuts whenseedbeds are prepared in the water.

Sheath blight also affects many grassesand weeds other than rice, causing similarsymptoms. Sclerotia that survive between

crops are formed on the surface of lesionson these weed grasses, as well as on riceand soybeans. The sclerotia are tightlywoven masses of fungal myceliumcovered by an impervious, hydrophobiccoating secreted by the fungus.

Disease severity can be reduced byintegrating several management practices.Dense stands and excessive use offertilizer both tend to increase the damagecaused by this disease. Broadcast seedingtends to increase stand and canopydensity. Rotation with soybeans orcontinuous rice increases the amount ofinoculum in field soils. Fallow periods,with disking to control growth of grassweeds, will reduce inoculum in the soil.The pathogen also is known to infectsorghum, corn and sugarcane whenenvironmental conditions are favorable fordisease development.

Medium grain rice varieties are moreresistant to sheath blight than most of thelong grain varieties. Several recentlyreleased long grain varieties are moreresistant to sheath blight than the olderlong grain varieties (Table 12).

Fungicides are available for reducingsheath blight. Ask a Cooperative ExtensionService agent for the latest information onfungicides for sheath blight management.

Sheath RotThis disease is caused by the fungal

pathogen Sarocladium oryzae. Symptomsare most severe on the uppermost leafsheaths that enclose the young panicleduring the boot stage. Lesions are oblongor irregular oval spots with gray or light-brown centers and a dark reddish-brown,diffuse margin (Fig. 74), or the lesionsmay form an irregular target pattern. OnU.S. rice varieties, the lesion is usuallyexpressed as a reddish-brown discolorationof the flag leaf sheath. Early or severeinfections affect the panicle so that it onlypartially emerges. The unemerged portionof the panicle rots, turning florets red-brown to dark brown. Grains fromdamaged panicles are discolored reddish-brown to dark brown and may not fill. Apowdery white growth consisting ofspores and hyphae of the pathogen may

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be observed on the inside of affectedsheaths. Insect or mite damage to the bootor leaf sheaths increases the damage fromthis disease.

This disease affects most rice varieties.The disease is usually minor, affectingscattered tillers in a field. Occasionally,larger areas of a field may have significantdamage. Control measures are notrecommended. Fungicidal sprays used in ageneral disease management programreduce damage, but recent studies showthat several bacterial pathogens commonlycause similar sheath rot symptoms on ricein Louisiana. Fungicides would have littleeffect on these pathogens.

Sheath SpotThis disease is caused by the fungus

Rhizoctonia oryzae. The diseaseresembles sheath blight, but is usually lesssevere. The lesions produced by R.oryzae are found on sheaths midway upthe tiller or on leaf blades (Fig. 76).Lesions are oval, 0.5 - 2 cm long and 0.5 -1 cm wide. The center is pale green,cream or white with a broad, darkreddish-brown margin (Fig. 77). Lesionsare separated on the sheath or blade anddo not form the large, continuous lesionsoften found with sheath blight. Thepathogen attacks and weakens the culmunder the sheath lesion on verysusceptible varieties. The weakened culmlodges or breaks over at the point whereit was infected. Lodging caused by sheathspot usually occurs midway up the culm.

This disease is usually minor onLouisiana rice. Some fungicides used tomanage sheath blight also reduce sheathspot.

StackburnThis disease was first observed on rice

growing in Louisiana and Texas. Stackburnor Alternaria leaf spot is caused by thefungal pathogen Alternaria padwickii. It isnow common on rice around the world.

The disease is present in all rice fieldsin Louisiana. Only occasional spots areobserved, but the disease may be moresevere in restricted areas of a field. Thespots are typically large (0.5 - 1 cm in

diameter), oval or circular, with a darkbrown margin or ring around the spot(Fig. 75). The center of the spot is initiallytan and eventually becomes white ornearly white. Mature spots have smalldark or black dots in the center. These aresclerotia of the fungus. Grain or seedsaffected by the disease have tan to whitespots with a wide, dark brown border.The disease causes discoloration ofkernels, or the kernels stop developmentand grains are shriveled.

This fungus is the most commonseedborne fungus in Louisiana and maycause seedling blight. It is more commonon panicles and grain than on leaves inLouisiana.

No specific control recommendationsare available, but seed-protectantfungicides will help reduce the seedlingblight caused by this pathogen and willreduce the number of spores available tocause leaf infections.

Stem RotStem rot caused by the fungus

Sclerotium oryzae is an important diseasein Louisiana. Often, losses are notdetected until late in the season when it istoo late to initiate control practices. Stemrot causes severe lodging, which reducescombine efficiency, increases seedsterility and reduces grain filling.

The first symptoms are irregular blackangular lesions on leaf sheaths at or nearthe water line on plants at tillering or laterstages of growth (Fig. 58). At later stagesof disease development, the outer sheathmay die, and the fungus penetrates to theinner sheaths and culm. These becomediscolored and have black or dark brownlesions. The dark brown or black streakshave raised areas of dark fungal myceliumon the surface and gray mycelium insidethe culm and rotted tissues. At maturity,the softened culm breaks, infected plantslodge and many small, round, blacksclerotia develop in the dead tissues (Fig.59).

The pathogen overwinters as sclerotiain the top 2 - 4 inches of soil and on plantdebris. During water-working andestablishment of early floods, the

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hydrophobic sclerotia float on the surfaceof the water and often accumulate alongthe edge of the field and on leveesbecause of wind action.

After a permanent flood is established,the sclerotia float to the surface, contactthe plant, germinate and infect the tissuesnear the waterline. The fungus thenpenetrates the inner sheaths and culm,often killing the tissues. The funguscontinues to develop, forming manysclerotia in the stubble after harvest.

Most commercial varieties of rice arenot highly resistant to stem rot. Thedisease is favored by high nitrogen levels.Early maturing varieties are usually lessaffected by stem rot. In addition,applications of potassium fertilizer reducedisease severity in soils where potassiumis deficient. Stem rot is more serious infields that have been in rice production forseveral years.

Suggested management measuresinclude using early maturing varieties,avoiding very susceptible varieties,burning stubble or destroying bycultivation after harvest to destroysclerotia, using crop rotation whenpossible, applying potassium fertilizer,avoiding excessive nitrogen rates andusing foliar fungicides recommended bythe Cooperative Extension Service. Severalcultural practices may reduce stem rot.These include fluctuating the water levelin the field so stagnant water does notremain at the same level on the lower leafsheaths, and draining water from the fieldat the tillering and early jointing stages ofgrowth, while keeping the soil saturated.These practices may lead to thedevelopment of leaf blast and otherproblems, however.

Water-Mold and Seed-RotWith the extensive use of the water-

seeding method of planting rice, it hasbecome more difficult to obtain uniformstands of sufficient density to obtainmaximum yields. The most importantbiological factor contributing to thissituation is the water-mold or seed-rotdisease caused primarily by fungi in thegenera Achlya and Pythium. Recently,

certain Fusarium spp. also have beenfound associated with molded seeds. Thedisease is caused by a complex of thesefungi infecting seeds. The severity of thisdisease is more pronounced when watertemperatures are low or unusually high.Low water temperatures slow thegermination and growth of rice seedlings,but do not affect growth of thesepathogens. In surveys conducted inLouisiana during the early 1970s and1980s, an average of 45 percent of water-planted seeds were lost to water-mold.

In addition to the direct cost of the lostseeds and the cost of replanting, water-mold also causes indirect losses caused bythe reduced competitiveness of rice withweeds in sparse or irregular stands. Also,replanting or overseeding the field causesthe rice to mature late when conditions areless favorable for high yields because ofunfavorable weather and high diseasepressure.

Water-mold can be observed throughclear water as a ball of fungal strandssurrounding seeds on the soil surface.After the seeding flood is removed, seedson the soil surface are typicallysurrounded by a mass of fungal strandsradiating out over the soil surface from theaffected seeds (Figs. 68). The result is acircular copper-brown or dark green spotabout the size of a dime with a rotted seedin the center. The color is caused bybacteria and green algae which are mixedwith the fungal hyphae.

Achlya spp. (Fig. 68) normally attackthe endosperm of germinating seeds,destroying the food source for the growingembryo and eventually attacking theembryo. Pythium spp. (Fig. 69) usuallyattack the developing embryo directly.When the seed is affected by the disease,the endosperm becomes liquified andoozes out as a white, thick liquid when theseed is mashed. The embryo initially turnsyellow-brown and finally dark brown. Ifaffected seeds germinate, the seedlingshoot and root are attacked and theseedling is stunted. When infection byPythium spp. takes place after theseedling is established, the plant is stunted,turns yellow and grows poorly. If the

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weather is favorable for plant growth,seedlings often outgrow the disease andare not severely damaged.

The disease is less severe when rice iswater-seeded when weather conditionsfavor seedling growth. High and lowtemperatures averaging above 65 degreesF favor seedling growth, and water-moldis less severe. Seeds should be vigorousand have a high germination percentage.Seed with poor vigor will be damaged bywater-mold fungi when water-seeded.

Treat seed with a recommendedfungicide at the proper rate to reducewater-molds and seed diseases. A list ofrecommended fungicides is availablethrough Cooperative Extension Serviceagents. Most rice seed is treated by theseedsman and is available to the groweralready treated. Seed-protectantfungicides differ in their effectiveness.Information on recent results from seed-protectant fungicide trials can be obtainedfrom an extension agent or the RiceResearch Station. In field tests, thesefungicides have increased stands overthose produced by untreated seeds from25 percent to 100 percent.

White TipThis disease is caused by the

nematode Aphelenchoides besseyi.Characteristic symptoms which appearafter tillering include the yellowing ofleaf tips, white areas in portions of theleaf blade (Fig. 86), stunting of affectedplants, twisting or distortion of the flagleaf, and distortion and discoloration ofpanicles and florets. Leaf tips changefrom green to yellow and eventuallywhite. The tip withers above the whitearea, becoming brown or tan and tatteredor twisted. Resistant varieties may showfew symptoms and still have yield loss.The nematode infects the developinggrain and is seedborne.

This disease is present endemically inLouisiana, but is considered a minor ricedisease. Fumigation of seeds in storagewill reduce the nematode population. Noother specific control measures arerecommended.

Physiological DisordersCold Injury

Cold weather affects rice developmentmost at the seedling or reproductivestages of growth. Seedling damage isexpressed as a general yellowing of theplants or as yellow or white bands acrossthe leaves where a combination of windand low temperature damaged the plantsat the soil line (Fig. 84). Cold weather(less than 60 degrees F) present duringthe reproductive stages causes panicleblanking or blighting. Individual florets orthe whole panicle may be white whenemerging. To eliminate this problem,adjust planting date to avoid lowtemperatures.

Panicle BlightThe cause of panicle blight is

unknown. It can be severe on certainvarieties of rice. The disease ischaracterized by brown or straw-coloreddiscoloration of florets on a paniclebranch (Fig. 82). Lesions are not apparentbelow the grain, thus panicle branchesremain green. The grain stops developingand the florets turn gray. It is more severein late planted rice where the rice ismaturing and late night temperatures arehigh.

SalinitySoil alkalinity, or salinity, and water

salinity injure rice and are characterizedby areas of stunted, chlorotic plants in thefield (Fig. 85). Under severe conditions,leaves turn from yellow to white, andplants die. Affected areas usually havedead or dying plants in the center or onhigh spots, with stunted yellow or whiteplants surrounding that area and green,less affected, plants in lower areas. Saltdeposits may be seen on the edges ofleaves, on clods of soil and other highareas of the field. Damage is reduced byflushing with water low in salt.

StraightheadThis physiological disorder is

associated with sandy soils, fields witharsenic residues or fields having largeamounts of plant residue incorporated into

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the soil before flooding. Panicles areupright at maturity because the grain doesnot fill or panicles do not emerge from theflag leaf sheath. Hulls (palea and lemma)may be distorted and discolored, withportions missing or reduced in size.

Distorted florets with a hook on the endare called “parrot beak” (Fig. 83) and aretypical of straighthead. Plants are darkergreen or blue-green and often producenew shoots and adventitious roots from thelower nodes. These symptoms can be

mimicked by herbicide damage. Manageby using resistant varieties (Table 12) anddraining at the first internode elongatingstage of growth to dry the soil until itcracks. Do not plant susceptible varietiesunder conditions favorable for straightheaddevelopment, which include very sandysoils, soils with high levels ofundecomposed plant residue or fields witha history of arsenical herbicide (such asMSMA) applications.

Table 12. Reaction of rice varieties commonly grown in Louisiana to commonTable 12. Reaction of rice varieties commonly grown in Louisiana to commonTable 12. Reaction of rice varieties commonly grown in Louisiana to commonTable 12. Reaction of rice varieties commonly grown in Louisiana to commonTable 12. Reaction of rice varieties commonly grown in Louisiana to commondiseases and disordersdiseases and disordersdiseases and disordersdiseases and disordersdiseases and disorders

NarrowSheath brown Brown leaf Leaf

Cultivar Blast blight spot spot smut Straighthead

Long grainLong grainLong grainLong grainLong grain

Akitakomachi MR S MR R MR SAlan S S MS MR S MSCypress MS S MR MR MS MRDella S S MR S MS SDellrose S S MS MS MS MRDixiebelle S S-VS MR MS MR VSDrew MR S MR MR MR MSGulfmont S VS R S MS-S MRJackson S S MR MS MR MRJasmine 85 R R MS-S R R VSJefferson MS S MR MR MR MSJodon S S MR MS MS VSKaty MR MS R MR MS MSKaybonnet R-MR MS-S MS MS MS SLacassine S S-VS MS MR R MSLaGrue S-VS S R-MR R R SLemont S S-VS MS-S S S MRLitton MS MS — — — MSMaybelle S S MR MS S MRMillie MS-S MS R MR MR MSPriscilla MS MS — — — MSTORO-2 R MS-S MR-MS MS MR-MS VS

Medium grainMedium grainMedium grainMedium grainMedium grain

Bengal S MS MS MR MS VSLafitte MR MS MR R MS VSMars S MS MS MR MS VSRico-1 S MS S MS MS MRSaturn MR MS-S MS S S S

R = resistant, MR = moderately resistant, MS = moderately susceptible S = susceptible, and VS =very susceptible. Varieties labeled S or VS for a given disease or disorder may be severely damagedunder conditions favoring disease development.

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Table 13. Scouting and management practices recommended for major riceTable 13. Scouting and management practices recommended for major riceTable 13. Scouting and management practices recommended for major riceTable 13. Scouting and management practices recommended for major riceTable 13. Scouting and management practices recommended for major ricediseases.diseases.diseases.diseases.diseases.

BLASTBLASTBLASTBLASTBLASTScouting or Determining Need

Varieties with low levels of resistance should be scouted for leaf blast during the vegetativestages of growth. Leaf blast is more likely when the flood is lost, excessive nitrogen is used orrice is planted late in the growing season. Sandy soils and tracts near tree lines are probableareas where blast will occur. There are no predictive systems to foresee when rotten neck blastwill occur. Since significant damage is already done when the disease is first detected,preventive sprays are required on susceptible varieties, especially when blast has beendetected in the region.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesPlant varieties resistant to blast. Avoid late planting. Plant as early as possible within your

recommended planting period. For leaf blast, reflood if field has been drained. Maintain flood at4 - 6 inches. Do not overfertilize with nitrogen. Apply a fungicide if necessary. Contact yourcounty agent for the latest information on available fungicides and timing.

SHEATH BLIGHTSHEATH BLIGHTSHEATH BLIGHTSHEATH BLIGHTSHEATH BLIGHTScouting or Determining Need

Rice following rice or soybeans is more likely to be affected. Dense stands and excessivenitrogen favor disease development. Scout varieties from mid-tillering until heading. The fieldshould be sampled at several locations to determine the percentage of tillers infected. Sprayinga fungicide is warranted if 5 percent to 10 percent or 10 percent to 15 percent of the tillers areinfected on susceptible or moderately susceptible varieties, respectively.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesAvoid dense stands and excessive nitrogen fertilizer. Most long grain varieties have little

resistance to sheath blight. Medium grain varieties are more resistant. Timing and rate offungicide applications are critical for good sheath blight management. Check with your countyagent for the latest information on fungicides. Fallow periods, with disking to control grasses inthe field (which serve as sources of inoculum) and break down crop residue, help reducedisease pressure.

BROWN SPOTBROWN SPOTBROWN SPOTBROWN SPOTBROWN SPOTScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining Need

Disease is most severe when plants are nitrogen deficient or under other stresses. Plantsbecome more susceptible as they approach maturity.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesMaintain good growing conditions through proper fertilizer, land leveling, good soil

preparation and other cultural practices. Use recommended seed protectant fungicides to reduceinoculum. Correct stress conditions in the field. All varieties are susceptible, but some more thanothers.

NARROW BROWN LEAF SPOTNARROW BROWN LEAF SPOTNARROW BROWN LEAF SPOTNARROW BROWN LEAF SPOTNARROW BROWN LEAF SPOTScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining Need

Disease is most severe from panicle emergence to maturity. Several pathogenic races arepresent, and new races develop to affect resistant varieties.

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Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesMany commercial varieties have acceptable levels of resistance to this disease. Check with

your Cooperative Extension Service agent for latest information on the use of availablefungicides. Apply fungicides at recommended rate and timing.

STEM ROTSTEM ROTSTEM ROTSTEM ROTSTEM ROTScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining Need

Most commercial varieties are susceptible. Infection takes place at the waterline, andangular black lesions form. The number of infected tillers may reach 100 percent in areas ofthe field where debris and sclerotia from the previous crop have collected after beingwindblown on the water surface.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesApplying potassium will reduce disease severity where potassium is deficient. Early

maturing varieties are less affected by stem rot. Destroying the sclerotia in stubble by croprotation, tillage or burning can reduce disease pressure.

WWWWWAAAAATERMOLD AND SEED-ROTTERMOLD AND SEED-ROTTERMOLD AND SEED-ROTTERMOLD AND SEED-ROTTERMOLD AND SEED-ROTScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining Need

The fungi causing this disease are soil- and waterborne. They occur in most rice fields. Theseed-rot and water mold disease is most severe under flooded conditions when the water iscold.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesSeed should be treated with recommended fungicides. Check with your county agent for

recent information on effective seed-protectant fungicides. Draining the seeding flood andflushing as needed help prevent watermold. Seeding should not begin until the mean dailytemperature reaches 65 degrees F.

SEEDLING BLIGHTSEEDLING BLIGHTSEEDLING BLIGHTSEEDLING BLIGHTSEEDLING BLIGHTScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining Need

The fungi causing this disease can be seedborne or soilborne. They are common and arenormally present on seeds or in soil. Seedling blight is common in drillseeded or dry broadcastrice.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesTreating seed with seed-protectant fungicides effectively reduces seedling blight. Check

with your extension agent for recent information on effective seed-protectant fungicides.

GRAIN SPOTTING AND PECKY RICEGRAIN SPOTTING AND PECKY RICEGRAIN SPOTTING AND PECKY RICEGRAIN SPOTTING AND PECKY RICEGRAIN SPOTTING AND PECKY RICEScouting and Determining NeedScouting and Determining NeedScouting and Determining NeedScouting and Determining NeedScouting and Determining Need

Since these diseases are normally associated with insect damage, scout for the rice stinkbug. Monitor fields from immediately after pollination until kernels begin to harden. Samplewith a sweep net and count the number of insects collected. If the number of stink bugsexceeds 30 per 100 sweeps during the first two weeks after heading, treat the field with alabeled insecticide. During the dough stages, fields should be treated when 100 or more stinkbugs are collected per 100 sweeps.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesControl of the stink bugs with insecticides is the only management measure for grain

spotting and pecky rice.

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and other bodies of water. Adult midgesresemble small mosquitoes but lack theneedle-like mouthparts and hold theirforelegs up when resting. Eggs areelongate and laid in strings, usually on thesurface of open water. The strings are heldtogether by a sticky material that forms agelatinous coat around the eggs. Afteremerging, the larvae move to the soilsurface, where they live in spaghetti-liketubes constructed from secreted silk, plantdebris and algae (Fig. 89). The larvae gothrough four instars before pupating underwater in the tubes. The life cycle from eggto adult requires 10-15 days.

InjuryInjuryInjuryInjuryInjuryMidge larvae injure rice by feeding on

the embryo of germinating seeds and onthe developing root and shoot of youngrice seedlings. Most economic injury to riceis the result of stand loss caused by larvaefeeding on the embryo of germinatingseeds. Reports of injury caused by riceseed midge have increased in recent years.

Scouting and ManagementRice seed midge is a problem only for

rice seeds and seedlings in water-seededfields. Midges are not a problem in ricemore than 2 to 4 inches tall. Scout fieldsfor midges and midge injury within five toseven days after seeding. Repeat scoutingat five- to seven-day intervals until riceseedlings are about 3 inches tall. Midge

KERNEL SMUTKERNEL SMUTKERNEL SMUTKERNEL SMUTKERNEL SMUT, LEAF SMUT, LEAF SMUT, LEAF SMUT, LEAF SMUT, LEAF SMUT, SHEA, SHEA, SHEA, SHEA, SHEATH ROTTH ROTTH ROTTH ROTTH ROT, SHEA, SHEA, SHEA, SHEA, SHEATH SPOTTH SPOTTH SPOTTH SPOTTH SPOT, LEAF SCALD,, LEAF SCALD,, LEAF SCALD,, LEAF SCALD,, LEAF SCALD,STSTSTSTSTACKBURN, ROOT ROTACKBURN, ROOT ROTACKBURN, ROOT ROTACKBURN, ROOT ROTACKBURN, ROOT ROT, ROOT KNOT, ROOT KNOT, ROOT KNOT, ROOT KNOT, ROOT KNOT, WHITE TIP, WHITE TIP, WHITE TIP, WHITE TIP, WHITE TIP, P, P, P, P, PANICLE BLIGHTANICLE BLIGHTANICLE BLIGHTANICLE BLIGHTANICLE BLIGHT, DOWNY, DOWNY, DOWNY, DOWNY, DOWNYMILDEWMILDEWMILDEWMILDEWMILDEW, F, F, F, F, FALSE SMUTALSE SMUTALSE SMUTALSE SMUTALSE SMUT, BACTERIAL LEAF BLIGHT, BACTERIAL LEAF BLIGHT, BACTERIAL LEAF BLIGHT, BACTERIAL LEAF BLIGHT, BACTERIAL LEAF BLIGHT, BLACK KERNEL, CROWN ROT, BLACK KERNEL, CROWN ROT, BLACK KERNEL, CROWN ROT, BLACK KERNEL, CROWN ROT, BLACK KERNEL, CROWN ROT,,,,,CROWN SHEATH ROTCROWN SHEATH ROTCROWN SHEATH ROTCROWN SHEATH ROTCROWN SHEATH ROTScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining NeedScouting or Determining Need

These diseases rarely occur with enough severity to warrant control measures orscouting.

Management PracticesManagement PracticesManagement PracticesManagement PracticesManagement PracticesControl measures are not available or recommended for these diseases. Varieties differ

in their reaction to these diseases, but extensive evaluations have not been conducted.Fungicides used to manage other major diseases reduce several of these diseases. Checkwith your county agent for the latest information.

Insect ManagementDennis R. Ring, James Barbour, William

C. Rice, Michael Stout and Mark Muegge

Insects can be a major factor limitingrice production in Louisiana. The rice waterweevil and the rice stink bug are keypests. They cause significant reduction inthe quantity and quality of rice producedeach year in Louisiana. Other insectsattacking rice, though not key pests, canoccasionally reduce rice yield and qualitysignificantly. These include the rice seedmidge, rice leaf miner, fall armyworm,chinch bug, rice stalk borer and sugarcaneborer.

This section contains information aboutthe identification, life cycle, injury to riceand current scouting and managementpractices for these pests. The scouting andmanagement recommendations are basedon the best available information and willbe modified as additional research isconducted. Current treatmentrecommendations are summarized in Table14, but consult your county agent and themost recent “Insect Control Guide”(Louisiana Cooperative Extension Servicepublication 1838) to get the latestrecommendations for specific insect pests.

RRRRRICEICEICEICEICE S S S S SEEDEEDEEDEEDEED M M M M MIDGEIDGEIDGEIDGEIDGE, , , , , ChironomusChironomusChironomusChironomusChironomus spp. spp. spp. spp. spp.Description and life cycle

Adult midges can be seen in swarmsover rice fields, levees, roadside ditches

8686868686

presence is indicated by larval tubes on thesoil surface (Fig. 89). There are manymidge species, most of which do not attackrice, and the presence of midge tubes alonedoes not indicate the need to treat a givenfield.

Midge injury is indicated by thepresence of chewing marks on the seed,roots and shoots and by the presence ofhollow seeds (Fig 90). If midge injury ispresent, and plant stand has been reducedto fewer than 15 plants per square foot,treatment may be necessary. The onlyavailable method for control of rice seedmidge is to drain fields to reduce numbersof midge larvae. Re-seeding of heavilyinfested fields may be necessary. Thepotential for damaging levels of seed midgecan be reduced or prevented by usingrecommended water and crop managementpractices. Holding water in rice fields formore than two to three days before seedingencourages the buildup of large midgenumbers before seeding and should beavoided. Practices that encourage rapidseed germination and seedling growth, suchas using pre-sprouted seed and avoidingplanting in cool weather, will help to speedrice through the vulnerable stage andreduce the chances for serious damage.

Chinch bug, Chinch bug, Chinch bug, Chinch bug, Chinch bug, Blissus leucopterusBlissus leucopterusBlissus leucopterusBlissus leucopterusBlissus leucopterusleucopterusleucopterusleucopterusleucopterusleucopterus (Say) (Say) (Say) (Say) (Say)Description and life cycleDescription and life cycleDescription and life cycleDescription and life cycleDescription and life cycle

Chinch bugs overwinter as adults ingrass clumps, leaf litter and other protectedareas, emerging in early- to mid-spring tofeed and mate on grass hosts includingsmall grains such as wheat, rye, oats andbarley. Adults are small, black insects about1/6-inch long, with white front wings (Fig.91). Each wing has a triangular black spotnear the outer wing margin. Adults laywhite, elongate eggs 1/24-inch long behindthe lower leaf sheaths or in the soil near theroots. Eggs turn red as they mature andlarvae emerge in seven to 10 days. Thereare five nymphal instars. Early instarnymphs are red with a yellow band on thefront part of the abdomen. Last instarnymphs are black and gray with aconspicuous white spot on the back (Fig.91). The life cycle from egg to adult takes

30-40 days, and adults may live two tothree weeks.

InjuryChinch bugs are a sporadic pest of rice

in Louisiana. Economic injury to ricegenerally occurs when favorable weatherconditions and production practices allowchinch bugs to build in corn, sorghum andwheat fields. As these crops mature and areharvested, large numbers of chinch bugsmay move to young plants in nearby ricefields. Serious economic losses haveresulted from chinch bug infestations innorth Louisiana. The trend toward increasingacreage of small grains increases thepotential for chinch bug problems.

Chinch bug injury results when adultsand nymphs feed on the leaves and stemsof rice plants. Feeding on young seedlingscauses leaves and stems to turn light brown.High numbers of chinch bugs can killyoung plants, severely reducing plantstands.

Scouting and ManagementCheck unflooded rice near small grain

fields every three to five days fromseedling emergence until application ofpermanent flood. Check foliage in ricefields for chinch bugs. Thresholds forchinch bugs in rice are not available. If highnumbers of chinch bugs are present andplant stands are being reduced, the fieldshould be treated. Cultural and chemicalcontrol methods are available. Culturalcontrol consists of flooding infested fields tokill chinch bugs or to force them to moveonto rice foliage where they can be treatedwith an insecticide. This tactic requires thatlevees be in place and that rice plants besufficiently large to withstand a flood.Cultural control may be more expensivethan chemical control. Contact your countyagent for specific recommendations ifchemical control is needed.

The Fall Armyworm, Spodopterafrugiperda (J. E. Smith)Description and Life Cycle

The fall armyworm feeds on mostgrasses found in and around rice fields. It isalso a serious pest of corn and pasture

8787878787

grasses. Since rice is not its preferred host,the fall armyworm is only an occasionalpest on rice. Adult moths are about 1 inchlong with gray-brown sculptured frontwings and whitish hind wings. The frontwings of male moths have a white bar nearthe wing tip. This bar is absent in femalemoths. Females lay masses of 50 to severalhundred whitish eggs on the leaves of riceand other grasses in and around rice fields.Egg masses are covered with moth scalesand appear fuzzy.

The larvae emerge in two to 10 days,depending on temperature, and beginfeeding on rice plants. They vary from lightgreen to brown to black, but havedistinctive white stripes along the side andback of the body. Larvae feed for two tothree weeks, developing through fourinstars. Mature larvae are about 1 inch longand have a distinctive inverted “Y” on thehead. Mature larvae prepare a cocoon andpupate in soil or decomposing plantmaterial. Moths emerge in 10 to 15 days,mate and disperse widely before layingeggs on new plants. At least fourgenerations per year occur in Louisiana.

InjuryFall armyworm larvae feed on the

leaves of young rice plants, destroyinglarge amounts of tissue. Leaf loss of 25percent in the seedling stage can reducerice yields by about 130 pounds per acre.When large numbers of armyworms arepresent, seedlings can be pruned to theground, resulting in severe stand loss. Fallarmyworm infestations generally occuralong field borders, levees and in highareas of fields where larvae escapedrowning. The most injurious infestationsoccur in fields of seedling rice that are tooyoung to flood. Larvae from the firstoverwintering generation, occurring in earlyspring, are the most injurious. Infestationslater in the season may cause feeding injuryto rice panicles, although this is rare.

Scouting and ManagementAfter germination of seedlings, scout

fields weekly for larvae on plants. Sampleplants every 10 feet along a line across thefield, and repeat this process in a second

and third area of the field. Treat whenthere is an average of one armyworm pertwo plants.

Fall armyworm management consists ofcultural, chemical and biological control.Parasitic wasps and pathogenicmicroorganisms frequently reducearmyworm numbers below economicallevels. Since adults lay eggs on grasses inand around rice fields, larval infestationscan be reduced by effective managementof grasses. When fall armyworm numbersreach threshold levels, cultural or chemicalcontrol is needed. Cultural control consistsof flooding infested fields for a few hoursto kill fall armyworm larvae. This requiresthat levees be in place and that rice plantsbe large enough to withstand a flood.Cultural control may be more expensivethan chemical control. Contact your countyagent for specific recommendations ifchemical control is needed.

The Rice Leaf Miner,,,,, Hydrelia griseola(Fallen)Description and Life Cycle

Adults are dark flies with clear wingsand a metallic blue-green to gray thorax.Less than 1/4 inch long, they can be seenflying close to the water and lighting onrice leaves. White eggs are laid singly onrice leaves that float on the water.Transparent or cream-colored legless larvaeemerge in three to six days and beginfeeding between the layers of the rice leaf.Larvae become yellow to light green asthey feed. Mature larvae are about 1/4 inchlong (Fig. 92). The larvae feed for five to12 days before pupating. Adults emergeafter five to nine days and live two to fourmonths. Under ideal conditions the lifecycle can be completed in as little as 15days. In cool weather the life cycle canextend for more than one month.

InjuryThe rice leaf miner is a sporadic

problem in Louisiana. Problems are moresevere in continuously flooded rice thanin periodically flooded rice, and whenwater is more than 6 inches deep. Injuryis usually greatest on the upper side oflevees where water is deepest. The rice

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leaf miner attacks rice during the earlyspring. Injury is caused by larvae feedingbetween the layers of the rice leaf (Fig.93). Leaves closest to the water areattacked and killed. As larvae move upthe plant, additional leaves die. When leafminer numbers are high, entire plants candie, reducing stands severely (Fig. 94). InLouisiana, rice leaf miner seems to attackfields in the same vicinity year after year.

Scouting and ManagementScout fields for rice leaf miners by

walking through flooded rice fields andgently drawing the leaves of rice plantsbetween the thumb and forefinger. Bumpsin the leaves indicate the presence of leafminer larvae or pupae. If leaf miners arepresent and plant numbers are reduced toless than 15 per square foot, treatment isnecessary. Rice leaf miner managementinvolves cultural control or insecticideapplication, perhaps both. Maintainingwater depth at 4-6 inches will usuallyprevent problems with rice leaf miner. Ifleaf miners are present, lowering thewater level in rice fields so that riceleaves can stand up out of the water alsowill help to prevent injury. Contact yourcounty agent for specific controlrecommendations.

Rice Water Weevil, Lissorhoptrusoryzophilus Kuschel Kuschel Kuschel Kuschel KuschelDescription and Life Cycle

The rice water weevil is the mostinjurious insect pest in Louisiana riceproduction. Yield losses of more than1,000 pounds per acre can occur fromsevere infestations. The total annual lossin Louisiana attributed to this pest isbetween $9 million and $10 million.

Rice water weevil adults are grayish-brown beetles about 1/8 inch long with adark brown V-shaped area on their backs(Fig. 95). Rice water weevils overwinteras adults in grass clumps and grounddebris near rice fields. Wing muscles ofoverwintering adults degenerate so theseinsects cannot fly. When springtemperatures rise to 65 degrees F, wingmuscles begin to regenerate and adultsbegin moving out of overwintering sites.

Adults fly in the early evening, with littleflight occurring when night-timetemperature falls below 60 degrees F.

Adults will invade either unflooded orflooded rice fields and begin feeding onthe leaves of rice plants. The flightmuscles degenerate again as the weevilsbecome established, and the adults cannotfly. Females begin egg laying in floodedfields or in areas of unflooded fields thatcontain water, such as low spots, potholesor tractor tire tracks. Females depositwhite, elongate eggs in the leaf sheath ator below the waterline. White, legless, C-shaped larvae with small brown headcapsules emerge from the eggs in aboutseven days.

First instar larvae are about 1/32 inchlong and feed in the leaf sheath for ashort time before exiting the stem andfalling through the water to the soil,where they burrow into the mud andbegin feeding on the roots of rice plants(Fig. 96). The larvae continue to feed inor on the roots of rice plants developingthrough four instars in about 27 days.Larvae increase in size with eachsucceeding molt. Fourth instar larvae areabout 3/16 inch long. Larvae pupate inoval, watertight cocoons attached to theroots of rice plants. The cocoons arecovered with a compacted layer of mudand resemble small mud balls (Fig. 97).

Adults emerge from the cocoons infive to seven days, are able to fly a shorttime after emerging and may attack rice inthe same or a different field. The lifecycle from egg to adult takes about 35days. The length of the life cycle istemperature-dependent, however, and canvary from 25 to 45 days in warm and coolweather, respectively. The number ofgenerations per year vary with latitude.Two and a partial third generation occurin the southern rice-growing areas ofLouisiana. One and a partial secondgeneration occur in the northern rice-growing areas. Most adult weevilsemerging in late July to early August (firstor second generation weevils in north orsouth Louisiana, respectively) fly tooverwintering sites and remain inactiveuntil the next spring.

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InjuryInjuryInjuryInjuryInjuryAdult rice water weevils feed on the

upper surface of rice leaves, leavingnarrow longitudinal scars that parallel themidrib (Fig. 98). Adult feeding injury cankill plants when large numbers of weevilsattack very young rice, but this is rare andis usually localized along the field borders.Most economic injury is caused by larvaefeeding in or on rice roots. This feedingor root pruning reduces root surface area,resulting in decreased nutrient uptake bythe plant. Plants with severely pruned rootsystems (Fig. 99) turn yellow and appearto be nitrogen deficient. At harvest, plantsfrom heavily infested fields will be shorterthan normal and have lower yields. Eachlarva found in a 4-inch (diameter) by 3-inch (deep) core sample reduces rice yieldby 40 pounds per acre.

Scouting and ManagementManagement practices for the rice

water weevil are changing. Furadan isexpected to be available on a limited basisto producers in the 1999 growing season.At the time of writing, the only othercompound which has received a label foruse is Karate.

Numbers of larvae on rice roots peak21-35 days after flooding. At this timemost of the larvae will be large, and asignificant amount of root pruning willhave occurred. Early scouting of fields canindicate if and when treatment is requiredto prevent damaging infestations resultingin reduced insecticide costs and higheryields.

Take the first larval count seven to 14days after establishment of the permanentflood in a drill-seeded system or 10 to 14days after plants have emerged from thewater in a water-seeded system. At leastsix sites should be randomly selected ineach field. At each site, remove a singlecore of plants and soil 4 inches indiameter and 3 inches deep and place it ina 10-quart bucket with a 40-mesh screenbottom (Fig. 100). Wash the soil from theplant roots through the screen bottom inthe bucket by thoroughly stirring the soilin the water. Push the bucket up and downvigorously in the water several times. This

forces water up through the screen bottomand helps to separate larvae from anyplant debris remaining in the bucket. Aftera few seconds, larvae will float to thesurface where they can be counted andremoved. Repeat the washing procedureseveral times to make sure all larvae in asample have been counted. If you don’tfind larvae in any sample, sample the fieldagain in five to seven days. If the averagenumber of larvae per sample is fewer thanfive, sample the field again three to fivedays later. If the average number of larvaeper sample is five or more, the fieldshould be treated. Sampling should ceasewhen the field has been treated or whenplants have reached the 2 mm paniclestage of development.

Timing of Karate is crucial, and morethan one application may be required.One day after permanent flood has beenestablished, begin scouting for adults.Examine plants in a one square foot areain five to 10 locations per field forpresence of adults. Continue scoutingevery three to four days until treatment isneeded. Treat when there is one adultweevil per square foot. Check at least 10locations before making a decision. Scoutand treat as needed until green ring, whenplants are no longer susceptible. Do NOTmake more than five applications at the3.84 fluid ounce per acre rate. Do NOTapply within 21 days of harvest.

Karate kills adult weevils, but not eggsand larvae. Egg laying (oviposition) mustbe prevented. Once eggs are laid in ricestems or larvae are in the roots, Karate isnot effective. Applying Karate for eggs orlarvae is a waste of money in addition tothe loss caused by weevils. Samplingplans and economic injury levels for therice water weevil are being developed.Recommendations for the management ofthe rice water weevil with foliarinsecticides may change.

Management of the Rice Water Weevilusing Cultural Control

Fields may be drained to reduce ricewater weevil numbers. Draining fields isthe only rice water weevil control methodavailable for rice grown in rotation with

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crawfish. Draining fields for rice waterweevil control requires careful planning soconflicts with weed, disease and fertilizermanagement programs can be avoided orminimized. Contact your county agent forspecific information on variety andmanagement practices for cultural controlor for specific chemical controlrecommendations.

The Stem Borers: The Rice StalkBorer, Chilo plejedellus (Zink)The Sugarcane Borer, Diatreasaccharalis (F.)

Description and Life Cycle, The RiceStalk Borer

The rice stalk borer is a sporadic pestof rice in Louisiana. Rice stalk borersoverwinter as last instar larvae in the stalksof rice and other host plants. Larvaepupate in the spring, and adult mothsemerge in early to late June, mate and liveon various hosts until rice stem diameter islarge enough to support tunneling larvae.Adults are about 1 inch long with palewhite fore and hind wings tinged on theedges with metallic gold scales. Frontwings are peppered with small black dots(Fig. 101). Although egg laying may beginin late May, injurious infestations usuallyoccur from August through September.Flat, oval cream-colored eggs are laid inclusters of 20 to 30 on the upper andlower leaf surfaces. Eggs are laid at nightover one to six days. Larvae emerge infour to nine days and crawl down the leaftoward the plant stem. Larvae may feedfor a short time on the inside of the leafsheath before boring into the stem. Theyare pale yellow-white with two pairs ofstripes running the entire length of thebody (Fig. 102). These stripes distinguishrice stalk borer larvae from sugarcaneborer larvae, which have no stripes.Mature larvae are about 1 inch long.Larvae move up and down the stemfeeding for 24 to 30 days before movingto the first joint above the waterline,chewing an exit hole in the stem andconstructing a silken web in which topupate. Pupae are about 1 inch long,brown and smoothly tapered. There aretwo to three generations per year in rice.

Description and Life Cycle,,,,,The Sugarcane Borer

The sugarcane bore is also a sporadicpest of rice in Louisiana. Like the stalkborer, sugarcane borers overwinter as lastinstar larvae in the stalks of rice and otherplants. These larvae pupate in the spring,and adult moths emerge as early as May,mate and live on various hosts until ricestem diameter is large enough to supportlarval feeding. Adults are straw-coloredmoths about 1 inch long with a series ofblack dots, arranged in a V-shaped pattern,on the front wings. Egg laying on rice canbegin as early as May, but economicallydamaging infestations generally do notoccur until August or September. The flat,oval, cream-colored eggs are laid at nightin clusters of two to 100 on the upper andlower leaf surfaces over one to six days.Larvae emerge in three to five days, crawldown the leaf and bore into the plantstem. They move up and down the stem,feeding for 15 to 20 days before chewingan exit hole in the stem and pupating.Larvae are pale yellow-white in thesummer, with a series of brown spotsvisible on the back (Fig. 103).Overwintering larvae are a deeper yellowand lack the brown spots. The lack ofstripes distinguishes sugarcane borerlarvae from rice stalk borer larvae, whichhave stripes in winter and summer (seeabove). Mature larvae are about 1 inchlong and do not enclose themselves in asilken web before pupation. The pupaeare brown, about 1 inch long and roughlycylindrical in shape, not smoothly taperedas are rice stalk borer pupae.Overwintering sugarcane borer larvae areusually found closer to the plant crownthan rice stalk borer larvae. The pupalstage lasts seven to 10 days. There arethree generations per year.

InjuryInjury to rice results from stalk and

sugarcane borer larvae feeding on planttissue as they tunnel inside the stem.Injury is often first noticed when theyoungest partially unfurled leaf of theplant begins to wither and die, resulting ina condition called deadheart (Fig 104).

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Later in the growing season, these ricestems are weakened and may lodge beforeharvest. Stem feeding that occurs duringpanicle development causes partial orcomplete sterility and results in the white-head condition (Fig. 105). The white,empty panicles are light in weight andstand upright.

Scouting and ManagementUnfortunately by the time signs of field

infestations (deadhearts, white-heads) arenoted, it is usually too late to applyeffective chemical treatments. For chemicaltreatments to be effective, you must timeapplication to coincide with larvalemergence so small larvae are killedbefore they enter rice stalks. Once larvaeenter the stalks, pesticides are noteffective. Extensive scouting of rice fieldsis required to time pesticide applicationsproperly. Scouting can be conducted forstem borer adults or egg masses. Eggs arelaid over an extended period, however,and although some injury may beprevented, satisfactory control usingchemical treatments is difficult and has notbeen generally successful. No pesticidesare labeled specifically for stem borercontrol in rice. Stem borer eggs and larvaeare parasitized by the wasps,Trichogramma minutum Riley and Agathisstigmaterus (Cresson), respectively. It isbelieved these parasites play an importantrole in maintaining stem borer numbersbelow economic levels.

Rice Stink Bug, Oebalus pugnax (F.)Description and Life Cycle

Adult rice stink bugs are shield-shaped,metallic-brown insects about ½ inch long(Fig. 106). Rice stink bugs overwinter asadults in grass clumps and ground cover.They emerge from overwintering sites inearly spring and feed on grasses near ricefields before invading fields of maturingrice. Adults live 30-40 days. Females laymasses of light-green cylindrical eggs onthe leaves, stems and panicles of riceplants. Eggs are laid in parallel rows withabout 20-30 eggs per mass. As theymature, eggs become black with a red tint.

Immature stink bugs (nymphs) emergefrom eggs in four to five days in warmweather or as long as 11 days in coolweather. Nymphs develop through fiveinstars in 15-28 days. Newly emergednymphs are about 1/16 inch long, with ablack head and antennae and a redabdomen with two black bars (Fig. 107).Nymphs increase in size with successivemolts and the color of later instars becomestan-green. There are four generations peryear in Louisiana, two on weed hosts andtwo on rice. Only one generation developsin a given field, however.

InjuryRice stink bugs feed on the rice florets

and developing rice kernels. Feeding onflorets reduces rough rice yields, but mosteconomic loss results from stink bugsfeeding on developing kernels. Kernelfeeding results in discolored or “pecky”rice kernels that have lower grade andpoor milling quality (Fig. 108). Both adultand nymph rice stink bugs feed ondeveloping rice grains, but adults aloneaccount for most economic losses in rice.Relationships between stink bugs and stinkbug injury developed in Texas show astrong increase in percentage of pecky riceand a strong decrease in percentage ofhead yield with increasing numbers ofadult stink bugs during the heading period.When numbers of immature stink bugswere included, this relationship did notchange.

Scouting and ManagementSeveral natural enemies are important in

reducing rice stink bug numbers in rice.Adults and nymphs are parasitized by theflies, Beskia aelops (Walker) and Eutheratentatrix Lav. Rice stink bug eggs areparasitized by the tiny wasps, Oencyrtusanasae (Ashm.) and Telonomus podisi(Ashm.). Management relies significantlyon the activity of these naturally occurringbiological control agents. Insecticidalcontrol based on the results of fieldscouting is recommended when rice stinkbugs escape from the control provided bynatural enemies.

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Rice fields should be sampled for stinkbugs using a 15 inch diameter insectsweep net once each week beginningimmediately after pollination andcontinuing until kernels harden. Do notsample fields at midday when stink bugsmay be seeking shelter from the heat inthe shade at or near the ground. Avoidsampling field borders, where stink bugnumbers are often higher than in the fieldinteriors, also. A sample consists of 10consecutive 180 degree sweeps madewhile walking through the field. Hold thenet so that the lower half of the opening isdrawn through the foliage. After 10successive sweeps, count the number ofrice stink bug nymphs and adults.Normally 10 samples of 10 sweeps eachare made per field. Alternatively, 100random sweeps may be taken per field.During the first two weeks of heading,fields averaging one or more rice stinkbugs per three sweeps (30 or more per

100 sweeps) should be treated with aninsecticide. After the first two weeks ofheading, treat fields when an average oneor more stink bugs per sweep (100 ormore per 100 sweeps) is found. Do nottreat fields within two weeks of harvest.Contact your county agent for specifictreatment recommendations.

Other Insect Pests of RiceSeveral other insects may occasionally

attack rice in Louisiana. They include thesouthern green stink bug, Nezara viridula(L.), several grasshopper species and thelarvae of several species of skippers (Figs.109, 110) and tiger moths. The numbers ofthese insects in rice fields are usuallybelow levels justifying treatment, but theymay increase rapidly under favorableconditions and yield losses can occur.Contact your county agent for specifictreatment recommendations.

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Table 14. Rice insect control recommendations.Table 14. Rice insect control recommendations.Table 14. Rice insect control recommendations.Table 14. Rice insect control recommendations.Table 14. Rice insect control recommendations.

Dosage Per AcreInsect Treatment Active Ingredient Limitations Remarks

Armyworms1 Methyl l/2 lb. ec l5 days Treat when there is oneParathion armyworm per two plants.

Malathion2 1.5 lb ec 15 daysB.t.2,3 0.5 lb 0 days

Chinch Bugs3 Methyl 3/4 lb. ec l5 days Flood fields first.Parathion

Rice Leaf Miners Methyl l/4 lb. ec 5 days Treat when stands areParathion reduced to less than 15 plants

per square foot.

Rice Stink Bug Malathion l/2 lb. ec 7 days Treat when there are 30 stinkSevin l to l l/4 lb. WP l4 days bugs per 100 sweeps during the

first two weeks of heading.Methyl l/4 lb. ec l5 days Treat when there areParathion 100 stink bugs per 100 sweepsPenncap M 1/4 lb. ec 15 days from two weeks after heading

begins until two weeks beforeMalathion2 0.5 lb 15 days harvest.

Rice Water Furadan4,5 l/2 lb. (l6 to 20 lbs. Treat when 40% of the plantsWeevil5 of 3% sand core granules) have feeding scars on

the newest unfurled leaf, and/orWater management2,6 when there is an average of 5 rice

water weevil larvae per core.

Rice Seed Drain fields Treat when stands are reducedMidge to less than 15 plants

per square foot.

1 Flooding is effective for armyworm control if plants are sufficiently developed. Do not use Methyl Parathionwithin 14 days of applying propanil.

2 For rice grown in rotation with crawfish.3 There are several formulations available. Follow label directions.4 Apply from one day before to four days after permanent flood for dark rice field mosquito control.5 Do not apply propanil after applying furadan. Do not apply to fields used for crawfish production. Do not

apply more than once per season.6 Consult your county agent for specific water management procedures.

WARNING: Re-entry times for workers entering treated fields should be strictly observed. Be sure to check thelabel for this information.

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Blackbird ControlJames F. Fowler and Joseph A. Musick

Blackbirds (Icterinae), are among themost numerous birds in rice-growing areas.The red-winged blackbird (Agelaiusphoeniceus) is the most abundant breedingbird in the rice-growing area ofsouthwestern Louisiana. Red-wingedblackbirds are responsible for most ricedepredation. Brown-headed cowbirds(Molothrus ater), common grackles(Quiscalus quiscula) and boat-tailedgrackles (Quiscalus major) cause the restof rice damage. Blackbirds are responsiblefor significant economic loss duringsprouting and ripening stages each year.Damage to sprouting rice can beparticularly severe in water-seeded rice.Most damage occurs in southwesternLouisiana where rice is seeded beforeresident flocks of blackbirds havedispersed to breed and before thedeparture of all wintering migrants. Asmany as 50 winter roost sites in Louisianamay be used by more than 125 millionblackbirds annually. Economic lossescaused by blackbird damage are mostsevere in fields located within five milesof winter roost sites. These areas aretraditionally adjacent to coastal marshes.

Both federal and state governmentsrecognize that blackbirds are importantdepredators of agricultural commodities.Blackbirds are migratory birds and areprovided protection under provisions ofthe Migratory Bird Treaty Act. They maybe controlled without a federal permitwhen found depredating agriculture crops,however. Louisiana considers blackbirdspests that may be taken any time by anylegal means.

No conventional agricultural pesticidesare labeled for use in reducing blackbirddamage in rice production. No lethalchemical compound that will controlblackbirds in agricultural crops safely andeffectively is likely to be registered forgeneral use by producers in the nearfuture. Methods of control involvealternative cultural practices, scare

Blackbird ControlJames F. Fowler and Joseph A. Musick

devices, chemical repellents and restricteduse toxicants.

Cultural Practices1. Drill seed rice on a well-prepared

seedbed. Water-plant only where acontinuous uniform flood of 2 to 6inches can be kept on the rice.

2. Delay planting rice in high blackbirdinfested areas (such as coastal areas)until after April 1. Arrange plantingprograms so fields near roost areas orcoastal marshes are planted last. Beginplanting nearest the farm headquartersand progress to more sensitive areaslater in the season.

3. Block planting in areas of traditionallysevere bird damage, such as in fieldsadjacent to coastal marshes, can beeffective in reducing damage on indi-vidual farms. This method requires thata group of farmers in a given area plantall or most of their rice on, or near, thesame date.

4. Consider alternate crops in high birdpressure areas where there has been ahistory of extreme damage to rice crops.

5. Habitat modification and clean croppingmay be helpful in reducing the numberof resident blackbirds damaging ricecrops at maturity. Removing brush andtrees from ditch banks, levees, fencerows and keeping fields free of weedswill eliminate blackbird habitat in andaround field areas.

Scare Devices1. Propane exploders with timers to turn

them off and on automatically each dayare the most effective scare devicesused to move feeding blackbirds fromfreshly planted rice fields and aftermaturity. There should be a least oneexploder for every 25 acres of crop tobe protected. They should be elevatedon a barrel, stand or truck bed to “shoot”over the crop. They should be movedaround the field every few days. Ex-

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ploders should be reinforced with liveammunition fired from shotgun and .22caliber rifles. In addition, pyrotechnicssuch as 12-gage shell crackers, rope firecrackers and rocket bombs can behelpful when used with live ammunitionand propane exploders.

2. Aircraft can be used to harass birds innewly planted fields, but this method iscostly under most situations.

Chemical Repellents1. Chemical repellents are compounds

which must be registered by EPA. Whenplaced on rice seed or other bait,repellents will deter consumption ofnewly planted seed by blackbirds. Theywork by causing olfactory, gustatory ordigestive irritation in the target animal.At present, no chemical repellents areregistered to protect newly planted riceseed.

2. Methyl anthranilate is a chemical com-pound that holds promise for protectingseed rice. Testing is under way.

Restricted Use Toxicants1. Avitrol (4-aminopyridine) is a poison

with flock-alarming properties used tocontrol blackbirds and starlings in, on oraround the area of feedlots, structures,nesting, roosting and feeding sites. Itacts in such a way that only a part ofthe flock feeding on the bait will ingesttreated bait, react and frighten the restaway. Birds that react and alarm a flock

usually die. Avitrol is for sale to and useonly by certified applicators or personsunder their direct supervision and onlyfor those uses covered by the CertifiedApplicators Certification. Distribution ofAvitrol should be limited to scatteredspot placements that will providefeeding opportunities only for thenecessary number of target birds. Afterthe birds’ feeding pattern has beenestablished through prebaiting, untreatedbait is removed and diluted treated baitapplied only at sites where the targetbirds are actively feeding. Do not applythis product where nontarget birdspecies are feeding. Treated bait shouldbe picked up and removed from thefield each day.

2. Compound DRC-1339 is an avicideregistered for use in parts of southwest-ern Louisiana under a 24 (C), local-needs label. It can be used only bypersonnel of the USDA Animal DamageControl Program and those workingunder their supervision. DRC-1339 isapplied to brown rice baits broadcast onblackbird staging areas near winter andspring roosting sites. Depending on thenumber of birds killed, the product issometimes effective in reducing ricedepredations associated with largeconcentrations of roosting blackbirds.DRC-1339 has not been effective whenused in areas where blackbirds arewidely dispersed.

Harvest and StorageHarvest and StorageHarvest and StorageHarvest and StorageHarvest and Storage

Harvesting RiceWilliam A. Hadden

Harvest ConsiderationsProper adjustment of harvesting

equipment is essential for reducing harvestloss and monitoring optimum harvestefficiency, but preharvest losses andmanagement losses can both result in poorharvest efficiency. Preharvest losses arecaused by factors such as adverse weather,bird depredation or damage caused by

certain insects and disease. Managementlosses are caused by premature drainingand improper harvest moisture.

Combine losses can be minimized withproper harvester adjustment. Lossesgenerally occur at the header (gatheringunit loss), at the cylinder or duringseparation. Gathering loss includesshattering, loose stalk and lodged stalkloss. Shatter loss occurs when loose grainsor panicles fail to enter the header. Loosestalk losses occur when panicles are cut

Harvest and StorageHarvest and StorageHarvest and StorageHarvest and StorageHarvest and Storage

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but do not enter the header. Lodged stalkloss occurs when panicles are broken overor separated from the plant before cutting.

Cylinder loss includes those grains ofrice which are left on the heads and arecarried out the rear of the combine.Separation loss is that portion of threshedgrain carried out of the combine with thestraw residue.

Rice harvest losses may be determinedby counting the number of grains persquare foot found to have been missed bythe combine. A count of 33 to 42 grainsper square foot (depending on the variety)equals 100 per acre.

Rice losses can be reduced by takingcertain measures. The moisture status ofthe crop needs to be determined beforeharvest. In general, most rice should beharvested when grain moisture rangesfrom 18 percent to 22 percent.

The combine should be operated atproper forward speed, platform height andreel speed. Cut as high as possible butwith enough straw to ensure efficientthreshing. Proper reel adjustment willprevent shattering and provide a uniformfeed into the header.

The proper cylinder speed maintainsgood threshing while preventing crackingand hulling of the rice. Excessive cylinderspeeds at lower moisture will increasekernel breakage. If the cylinder speed istoo slow, some of the grain will not beremoved, especially at higher moisture.

Separation losses can be decreased bymaintaining proper setting at the chafferand sieves. Adjust air flow to remove asmuch trash as possible without losing grainfrom the rear of the combine.

Combine CapacityA combine typically operates 50

percent to 80 percent of the time it is inthe field. This is known as its fieldefficiency. Harvesting speed usuallyranges from one to four miles per hour.The capacity of the combine can bedetermined with this formula:

C = S x W x Field Efficiency————————————— 825

Where:C = Capacity in acres per hourS = Speed, MPHW = Width, feet

Field Efficiency = 50 to 80 percent

Example:C = 2 x 20 x 60 = 2.9 acres/hour ___________ 825

Where: S = 2, W = 20, Field Efficiency= 60

Rice Drying and StorageDouglas L. Deason

The rice grain on a plant, and even ona single panicle, may vary considerably inmoisture content as the plant nearsreadiness for harvest. This is because ofgrain location on the plant and because ofthe time interval over which a plantblooms. When a sample is cut todetermine moisture content, an averagemoisture is determined; some grains arewetter and some drier than this averagemoisture. Harvesting at 18 percent to 22percent wet basis moisture content givesthe best milling yields. Most varietiesharvested at 23 percent and above tend tohave too many chalky immature kernels. Ifrice is allowed to field-dry to moisturesless than 16 percent, the driest kernels aresubjected to wetting and drying cyclescaused by air drying potential changesfrom day to night. This causes stress cracks(checks) in some of the kernels, reducingmilling yields. This reduction of millingyield as the rice dries is more severe insome varieties than others. Rapidrewetting by rain, once rice reaches 15percent or less moisture content, is a keycause of lower head rice yields. To obtainthe highest milling yields, some method ofartificially drying rice from harvestmoisture to a safe storage level of 12percent to 13 percent is necessary.

For a drying system to produce a highmilling, quality rice, the system must (1)operate so the rice is not overdried and (2)provide a controlled drying rate adequate

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to reduce rice from 22 percent to 16percent or below in no more than sevendays. If drying rates are slower than this,damage from molds and fungi will discolorthe milled kernels. This is called heatdamage or stackburn. At 16 percentmoisture or less, the rice does not providea favorable environment for mold andfungi growth, and moisture content can besafely reduced at a slower rate. A moisturecontent of not more than 13 percent in anyportion of the bin is recommended for safestorage. Rice mills prefer 12 percent to12.5 percent moisture for best millingresults.

Certain precautions should be takenbefore placing the season’s first rice inbins for drying. The bins and plenum areashould be cleaned thoroughly, allowed todry and treated for insects. Air leaksaround the base of bins and doors shouldbe caulked and rodent-proofed. Everyeffort should be made to place clean ricein the drying bins. This includes carefuladjustment and supervision of the harvest-ing equipment and providing for additionalcleaning at the bin location if necessary.Excessive foreign material in the grainsamples will cause uneven drying in thebins and increase the moisture content ofthe rice. If levees have more weeds thanthe fields, levee rice should be harvestedand dried separately.

Drying, Storage and EquipmentThe corrugated metal bin with full

perforated metal floors, tightly constructedto protect the rice from weather, insectsand rodents, is the centerpiece of ricedrying on farms in Louisiana. Other neces-sary items include drying fans and heaters,combination humidistat-thermostat control,adequate grain handling equipment,plenum temperature thermometers andample roof ventilators. Optional equip-ment includes grain stirring devices, grainspreaders and grain temperature monitor-ing equipment.

Modern rice drying bin systems shouldbe equipped with centrifugal fans althoughsome older farm bins with axial-flow fansadequately dry rice in shallow rice depths.

In general axial-flow fans will worksatisfactorily for drying up to a depth of 8feet if sized to deliver 2 ½ to 3 cfm (cubicfeet of air per minute) per bushel of rice.For use in bins where depths are morethan 8 feet, or in bins equipped withstirrers and drying depths to 16 or 17 feet,the centrifugal fan is an absolute necessity.

Drying Rice Without StirrersThis method of drying rice would be

described as drying a static bed of ricewith supplemental heat as necessary tokeep drying air at a desired humiditylevel. A minimum air flow rate of 9 cubicfeet per minute per barrel (9 cfm/bbl) or2.5 cubic feet per minute per bushel (2.5cfm/bu) is necessary to accomplish dryingwithout stackburn. A larger cfm/bu airflowrate will dry more rapidly. For most bin-fan combinations as installed, you can get2.5 cfm/bu with 7 to 9 feet of rice (a half-bin). Centrifugal fans can be selected tosupply 2.5 cfm/bu at depths of more than9 feet. The use of stirrers would not benecessary, but design depth should belimited by a static pressure requirement ofnot more than 5.5 inches. In principle thisdrying method uses a humidistat to turn onheat when the plenum air is above 65percent relative humidity. Generally, onlya slight increase in temperature isnecessary to reduce humidity below thehumidistat cut-off point. Under normaloperation of this system, burners will notadd heat when the air humidity is less than65 percent. The amount of heat addedwith this method is small, making this themost energy-efficient system. With thissystem supplying 2.5 to 3 cfm/bu, cleanrice at 22 percent moisture should dry to14 percent moisture in six to seven days.

In this static bed method of drying rice,drying moves from the bottom of the binupward, with the top layers drying last.Sample the top of the rice regularly asdrying progresses, and stop adding heatwhen the top 12 to 15 inches of rice are at15 percent moisture.

This static bed system of using ahumidistat to control supplemental heathas several shortcomings. Often the ricewill not dry evenly throughout the half-

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bin; the bottom will be drier than the top,and rice in the center of the bin will havehigher moisture content than grain nearwalls. Transfer of the half-bin of 14percent rice to another bin mixes the rice.This second bin can be filled with 14percent rice for completing drying to 12.5percent. For best milling yield, completethe drying and cooling without addingheat. This can be done by running the fansduring the daylight hours when the airhumidity is less than 65 percent.

Another shortcoming of this system isthat it is rather slow because only one-halfbin is dried at a time and smalltemperature increases are used. Fastharvest and large acreage will requirenumerous bins or other methods of drying.

A third drawback is that good resultsdepend on a properly operating humidistatto control the addition of heat to the dryingair. Check the humidistat for properoperation each year and service or replaceas necessary. The work of the fan willlower the relative humidity of outside airabout 5 percent. Turn heat on whenoutside air humidity is 70 percent or aboveto obtain 65 percent or less relativehumidity under the grain. If the humidistatis not operating properly, excessive heatmay be added, the bottom layers of thebin will be overdried and milling yieldswill be reduced.

When using the thermostat incombination with the humidistat, set thethermostat at 95 degrees F. Used in thismanner, the humidistat should control theburners to add heat, and the thermostatshould serve as a safety device to turnheat off above 95 degrees F. Efforts to drydeep layers of 8 to 9 feet of rice with onlya thermostat for controlling heat willgenerally give poor results if a stirringdevice is not used.

In recent years, several manufacturershave offered low temperature rise,modulating valve controlled heaters. Theseunits can provide precise temperaturecontrol of air under the drying floor. Thistype of controller is more energy efficientthan the older on-off controls. Drying deeplayers of rice (8 to 9 feet) with thistemperature controlled system will

probably provide faster drying whencompared to a humidistat controlledsystem. Using this temperature controlsystem in Louisiana, with a 90 degree Fcontrol point, relative humidity will bereduced to 50 percent to 55 percent.Producers have reported excellent millingquality on rice dried with this equipment.

Drying Rice With Stirring EquipmentStirring equipment for moving rice from

bottom of bin to top has some importantadvantages for rice producers. (1) Itreduces the risk of uneven drying fromoverdrying of lower layers caused bypoorly constructed and managedhumidistats. Rice directly in the bin’scenter is not stirred and generally remainsat a higher moisture level than rice inother areas. This must be carefullymonitored. (2) It reduces the problem ofhot spots and uneven drying caused bytrash separation in the bin. Vertical screwsdo a good job of evenly distributingforeign material and leveling the topsurface. (3) It allows the addition of alarger amount of heat and provides moredrying capacity with the same bin and fanequipment; most systems with stirrers candry at least twice as much rice in a givenperiod as can static bed - humidistatcontrolled drying. (4) It requires only athermostat.

The stirring device should be turned onand started when 2 feet of rice cover thefloor evenly. The stirrers should beoperated constantly throughout the dryingperiod and until rice is dry enough tocease adding heat to the air. Initialthermostat setting should be 90 degrees Funtil depth of rice is equal to one-fourth oftotal drying fill. For example, if 16 feet ofrice will be dried, the thermostat should beset to 90 degrees F for up to 4 feet ofdepth; from 4 to 8 feet, the thermostatshould be set to 95 degrees F. Increase thethermostat setting gradually to a maximumof 105 degrees F at maximum fill of 16 to17 feet. Airflow should be a minimum of1.25 cfm/bushel or 4.5 cfm/barrel atmaximum stirred drying depth. A 15 HPcentrifugal fan is required for a 27 feetdiameter bin, 20 HP for 30 feet diameter

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and 30 HP for 36 feet diameter bin. Two20 HP fans may provide a more even airand heat distribution with the 36 feetdiameter bin than will one 30 HP fan. With16 to 17 feet of rice and this airflow, thefans will operate against a static pressureof about 6 inches of water.

Properly managed stirrer equipped binsincrease drying capacity, reduce dryingrisk and result in more uniform milling.

Other Rice Drying MethodsLarge farm operations may have harvest

and drying rates that necessitateconsideration of methods other than thetwo research-proven methods discussed.One alternative to increasing dryingcapacity of a farm bin drying system is touse a continuous flow dryer to remove nomore than 3 percent or 4 percent ofmoisture initially. A continuous flow dryerneeds a large holding capacity, a lowheated air temperature and good mixingaction within the dryer. Rice graintemperatures coming from the dryershould not exceed 95 degrees F. Ricecoming from a continuous flow dryer atabout 17 percent to 18 percent moistureshould be transferred to a stirred bin tocomplete the drying operation. Beginningwith rice at a 22 percent moisture, thissystem must be managed carefully toprevent significant milling yield losses.Using a continuous flow dryer to remove 4percent to 5 percent moisture from riceinitially at 19 percent to 20 percentmoisture will probably cause significantmilling yield losses. No research hasshown this to be possible without costlyreduction of whole grain and total millingyield.

Another type of drying system nowbeing marketed in rice-growing areas is ahigh airflow in-bin continuous flowconcept. This system consists of a bin witha perforated floor and one or two fansdesigned to provide five to 10 cfm/bu ofairflow to as much as a 10-feet dryingdepth of grain. Unloading augers areinstalled on the floor of the bin and arecontrolled to operate so that a layer ofgrain is removed from the bottom of bin asit becomes sufficiently dry. This system is

energy-efficient relative to energyrequired per pound of water removed.This type of continuous flow system alsoprovides a relatively large volume of wetgrain storage ahead of the dryer.

The dryers should be operated at 4 to 6feet of rice depth with an intended airflow of about 10 cfm/bu of rice. The riceleaving the dryer should not have a graintemperature of more than 100 degrees Fto 105 degrees F. Base decisions on thisexit grain temperature on milling yield ofthe rice samples. The grain from this dryer(16 percent to 17 percent rice) is placedin nearly full bins at reduced risk tocomplete drying. Do not expect thiscontinuous bin dryer to remove 4 or morepercent of moisture from rice with initialmoisture of 20 percent or less withoutmilling yield loss. Most desirable operationof this continuous flow bin drying systemrequires a level grain surface across thefull bin width and uniform air temperaturesunder the bin. Both requirements aredifficult to achieve.

Management of Stored RiceAfter rice has been dried and cooled to

a moisture of 12 percent to 13 percent,sample it for temperature and moisturecontent during storage. Sample severaltimes in the first couple of weeks aftercompletion of drying because percentageof grain moisture often increases becauseof moisture migrating to the kernelsurfaces. Aeration is required when thisoccurs. Once grain moisture stabilizes,check moisture and temperature no lessthan once a month, preferably every twoweeks. High temperature spots indicatelocations with excess moisture and requireaeration.

As winter approaches, aeration can beused to lower the temperature of the grainmass. This will reduce temperaturedifferences in the bin which causemoisture migration in the grain mass. Highmoisture grain is most likely to occur inthe top center portion of the bin and alongthe walls. For aeration cooling purposes,operate fans when outside air temperatureis 10 degrees F or more below graintemperature. In Louisiana, relative

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humidity of the air blown during aerationmust be considered. Extended aeration athigh air flows and low humidities cancause severe overdrying of the bottom rice

layers in the bin. Preferred relativehumidity for aeration is in the 60 percentto 70 percent range. Do not operate fansduring fog or rain.

Rice EconomicsRice EconomicsRice EconomicsRice EconomicsRice EconomicsL. Eugene Johnson, G. Grant Giesler and Michael E. Salassi

Rice EconomicsRice EconomicsRice EconomicsRice EconomicsRice EconomicsL. Eugene Johnson, G. Grant Giesler and Michael E. Salassi

For many decades rice has been amongthe top cash crops produced in Louisiana.Rice production supports an infrastructureof storage, processing, transportation andagricultural supply industries larger thanthat of many other agricultural commoditiesproduced in the state.

Other major rice-producing states areArkansas, California, Mississippi, Missouriand Texas, which, together with Louisiana,accounted for an average of about 1.4percent of world rice production from1986 - 1997. During the same period,about 35 percent of this production wasexported, accounting for about 19 percentof total world trade in rice. More than 97percent of the world’s rice wasdomestically consumed in the countrywhere produced during this period.

Farm ManagementA key to successful farm management is

understanding and estimating enterpriseproduction costs. This is particularly truefor rice growers because rice is relativelyexpensive to produce compared to otherfield crops typically grown in Louisiana.Several production decisions which mustbe made during the growing season basedon the current status of the rice crop mayimpact costs significantly. Examples ofthese include insecticides, fungicides andfertilizer. All these decisions are partially afunction of environmental conditions thathave prevailed since planting andsubsequent effects on the yield potential ofa particular field of rice. Unfortunately,these effects cannot be accuratelypredicted on a yearly basis, so theirimpacts on production costs are among themost difficult to estimate before they occur.

A systematic method for estimatingproduction costs is an enterprise budget.An enterprise budget is simply an itemized

list of projected expenditures and returnsassociated with a given crop productionsystem. The budget includes the total inputrequirements for that enterprise based onthe sequence of operations. Its purpose isto summarize enterprise cost and returnprojections for use in managementdecisions. Much of the information neededto construct an enterprise budget isavailable from historical farm records andcurrent projections of input costs andoutput prices. Two illustrations ofenterprise budgets for rice are provided inTables 15 and 16.

In Table 15, the budget is typical of awater-planted owner-operator situation insouthwestern Louisiana. Owner-operatorscan compare their cost estimates with thebudget in Table 15 using the “Your Farm”column. Similarly, tenant-operators cancompare their situations with the projectedbudget presented in Table 16. In analyzingcrop enterprise budgets, it is extremelyimportant to evaluate the levels ofprofitability associated with various levelsof product price and yield projections.

Not all items in these tables are directcash outlays. Interest on operating capitaland certain items included in the fixedexpenses section of the budgets are notalways direct cash costs. Noncash expenseitems are used to approximate theeconomic cost associated with devotingcapital and machinery resources to the riceenterprise. An interest charge on operatingcapital indicates that money tied up in thecurrent year’s rice crop could be usedelsewhere. Items such as depreciation(economic, not tax, depreciation),insurance and housing (for equipment) aretypically included under the fixedexpenses category. These cost items mustbe covered if the farm business is to beprofitable in the long run.

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Using the cash expense information inthe enterprise budget, a farmer candevelop a whole-farm cash flow analysisfor the business. Cash flow analysissummarizes the sources and uses of cashin the business and requires estimatingtotal expenditures and receipts whichoccur during specified periods of the year(usually quarters). Cash flow deficits in agiven quarter indicate the need for costcontrol measures or possible borrowing.The best source of data for developing acash flow statement is historical farmrecords. (Monthly bank statements canprovide much of the needed information.)

An important, yet often neglected,aspect of farm management is the controlphase. Just as it is important to projectexpenditures and receipts for theupcoming season, it is important tocompare actual events and outcomes withearlier projections. Deviations in the actualoutcome from the initial projection can beanalyzed and become the basis for nextyear’s plan of action. This type ofcontinual monitoring of the businessallows the farmer to control his or heroperation better and to detect potentialproblems.

MarketingContrasted to that of other high energy

foods, rice consumption in the UnitedStates has been increasing for many years,especially since the early 1980s. In fiscal1993 it reached nearly 20 pounds ofmilled rice per capita, which does notinclude more than four pounds per capitaused in brewing. Projections for fiscal1996 indicate expected consumption percapita to increase to more than 21 poundsand four pounds respectively for food andbrewers’ use. Of the milled rice consumeddomestically, about 80 percent to 85percent is used directly for food andprocessed food, and 15 percent to 20percent for brewing. On a rough ricebasis, forecasted total domestic per capitause now amounts to more than 35 poundsper year (Table 17).

From fiscal years 1988 to 1995, U.S.rice exports were distributed as follows:

Mid-East, 39.51 percent; North America,18.26 percent; Caribbean Islands, 7.17percent; Africa, 9.73 percent; Asia, 7.39percent; Europe, 11.83 percent; and SouthAmerica, 6.11 percent. These percentagesare somewhat skewed because of largepurchases by Japan in 1993. Otherrelatively large exporting countries areThailand, Pakistan, Burma, Italy and, attimes, China, Japan and Taiwan.Aggregated world rice production andtrade data are in Table 18.

Because of the relatively large numberof buyers and public auctions operating inLouisiana, and the state’s proximity to bothdomestic markets and export facilities,Louisiana growers have perhaps a widerrange of marketing choices than growersin other rice-producing states. Louisianaranks second to Arkansas in number ofoperating rice mills.

Historically the South’s largest producerof medium grain rice, Louisiana was edgedout by Arkansas in 1995 in production ofmedium grain. From 1992 to 94, mediumgrain acreage has fluctuated from 30percent to 40 percent of total rice acreagein Louisiana, but fell to 23 percent in 1995and 13 percent in 1996.

Long grain rice generally commands ahigher price than medium grain rice of thesame grade (Table 19). Anticipatingpremiums the market will pay for longgrain rice is one of the most important, butmore difficult, marketing tasks manyLouisiana growers face.

Anticipating probable market prices foreither class has also become more difficultsince 1972. Further development offutures trading for rice holds somepromise in this regard as well as to createa large number of marketing alternativesnot previously available. In any case, agrower must choose when to sell, and thechoice will likely affect incomesignificantly in any given year. There isoften no way to predict prices with anydegree of certainty, and the choice ofwhen to sell is often dictated by financialcircumstances of individual growers.

Figure 111 (p. 105) shows the productsderived from milling 100 pounds of long

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grain rough rice. The exact proportions ofeach of the products produced depend ona number of management andenvironmental factors.

Rice is exported mainly in 100-poundand 50-kilo bags in the form of either rawor parboiled milled rice, but significantamounts also move to the export marketin bulk form as rough and brown rice, andin consumer packages.

U.S. Farm Policy for RiceIn general, the historical objectives of

government farm policy have been to 1)ensure a secure and wholesome foodsupply, 2) to maintain a viable agriculturalindustry and 3) to support the income offarmers. Government intervention into thedomestic agricultural industry began withthe Agricultural Adjustment Act of 1933,and rice was designated as one of theAct’s original seven commodities.Succeeding Acts have all had significantinfluence on the rice industry, resulting ina 92 percent to 95 percent participationrate of rice farmers in the rice programnationwide.

Government programs for rice in thefirst half of the 1990s were governed bythe Farm Bill of 1990. This bill resultedfrom two statutes, The Food, Agriculture,Conservation and Trade Act of 1990 andThe Agricultural Reconciliation Act of1990. Goals of the 1990 Farm Bill wereto: 1) further reduce the federal deficit byreducing payment acres, 2) help maintainfarm income growth through increasedplanting flexibility and expanding exportsthrough market-oriented loan rates and 3)enhance environmental quality throughthe Conservation Reserve Program and theWater Quality Protection Program.

Important provisions of the 1990 FarmBill (as compared to the 1985 bill)applicable to rice were: 1) freezing ofminimum target prices for five years at$10.71/cwt, 2) maintaining the currentmethod of loan rate calculation, 3)maintaining the current method ofdeficiency payment rate calculations for1991-93 crop years, with subsequentchanges for the 1994-95 crop years, 4)

changing triggers for acreage reductionprograms (ARP) and 5) introducing normaland optional flexibility acres (NFA andOFA). Provisions continued under the1990 Act included: voluntary compliance,marketing loans, nonrecourse loans basedon a loan rate, deficiency payments basedon a target price, crop acreage base,acreage reduction program, flexibilityacres and payment limitations.

With the passage of the new farm bill,the Federal Agriculture Improvement andReform Act of 1996, the role of thefederal government in price supportactivities for agricultural commodities,including rice, will change dramatically.The new program basically consists of aseven-year transition period, during whichtime government support payments foragricultural commodities will be reducedannually and producer returns fromproduction of these commodities willdepend more and more on market prices.

A summary of the rice provisions ofthe new farm bill is in Table 16. The newfarm program eliminates the rice targetprice/deficiency payment price supportsystem which has been in effect for manyyears. Eligible producers would enter intoa seven-year, production flexibilitycontract for the 1996-2002 period.Producers would receive guaranteed,direct, fixed payments on 85 percent ofeligible rice base acreage. Thesepayments would generally decline overthe seven years and would not be tied tomarket prices. Total annual commodityspending would be set in advance anddivided between commodities, basedpartly on previous payment history. Theshare of total commodity spendingallocated to rice is estimated at 8.47percent under this new bill, compared to12 percent to 13 percent paid to riceproducers over the previous severalyears.

Transition payments for rice under thenew farm program are projected to rangefrom $2.94 down to $2.03 perhundredweight over the 1996-2002period. Payments would be based onestablished rice program yields and paid

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on 85 percent of eligible rice baseacreage. These payment rates comparewith a maximum deficiency payment rateof $4.21 per hundredweight under the1985 and 1990 farm bills.

Nonrecourse loans for commodities,including rice, were retained from theprevious farm program. The maximumloan rate for rice over the life of the billwas set at the 1995 level of $6.50 perhundredweight. Marketing loan provisions(LDP program) for rice were extendedfrom previous legislation with repaymentat world prices or 70 percent of loan, ifworld market prices are below the loanrate. Producers would be free to plant any

program crop, oilseed crop or industrial orexperimental crop on their paid rice baseacreage and could plant in excess of theirbase. Planting fruits and vegetables wouldbe prohibited on payment acres. Hayingand grazing would be permitted as a flexcrop on payment acreage. All acreagereduction (set-aside) programs wereeliminated. Current payment limitationswere reduced from $50,000 to $40,000per entity, although the three-entityprovisions of the previous farm programwere retained. The bill extends provisionslimiting marketing loan gains and loandeficiency payments to $75,000 perperson per year.

Table 15. Estimated costs and returns per acre. Rice, water planted,Table 15. Estimated costs and returns per acre. Rice, water planted,Table 15. Estimated costs and returns per acre. Rice, water planted,Table 15. Estimated costs and returns per acre. Rice, water planted,Table 15. Estimated costs and returns per acre. Rice, water planted,ownerownerownerownerowner-operators, Southwest Louisiana, 1998.-operators, Southwest Louisiana, 1998.-operators, Southwest Louisiana, 1998.-operators, Southwest Louisiana, 1998.-operators, Southwest Louisiana, 1998.

_______________________________________________________________________ItemItemItemItemItem UnitUnitUnitUnitUnit PricePricePricePricePrice QuantityQuantityQuantityQuantityQuantity AmountAmountAmountAmountAmount Your FarmYour FarmYour FarmYour FarmYour Farm_______________________________________________________________________

dollars dollarsINCOMEa/

Rice cwt 10.00 48.0000 480.00 _________ Rice checkoff cwt 0.08 -48.0000 -3.84 _________

————TOTAL INCOME 476.16 _________

DIRECT EXPENSESCUSTOM Fertilizer Truck acre 3.50 1.0000 3.50 _________ Airplane seed cwt 4.55 1.4000 6.37 _________ Global Pos. System acre 0.45 6.3500 2.86 _________ Airplane Stam acre 5.15 2.0000 10.30 _________ Airplane furadanb/ acre 4.00 0.5200 2.08 _________ Airplane 2,4-D acre 5.10 1.0000 5.10 _________ Airplane Fert cwt 4.05 1.4000 5.67 _________ Airplane benlateb/ acre 4.50 0.7000 3.15 _________ Airplane Insectb/ acre 3.95 0.1300 0.51 _________ Drying Rice cwt 0.95 53.9300 51.23 _________ Storage Ricec/ cwt 0.40 48.0000 19.20 _________FERTILIZER Nitrogen lbs 0.23 120.0000 27.60 _________ Phosphate lbs 0.26 51.0000 13.26 _________ Potash lbs 0.14 51.0000 7.14 _________FUNGICIDES Quadrisb/ oz. 2.19 4.2000 9.20 _________ Benlate 50% WPb/ lbs 16.50 0.3500 5.77 _________

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HERBICIDES Stam M4 qt 4.58 6.0000 27.48 _________ 2,4-D-LV4 pt 1.78 1.0000 1.78 _________HIRED LABOR Other labor hour 7.50 1.0000 7.50 ________________________________________________________________________________Item Unit Price Quantity Amount Your Farm_______________________________________________________________________INSECTICIDES Furadan 3Gb/ lbs 0.80 8.8400 7.07 _________ Methyl parathion 4Eb/ pt 3.31 0.1300 0.43 _________OTHER Plastic sqft 0.08 13.5000 1.08 _________SEED Rice seed lbs 0.21 140.0000 28.70 _________OPERATOR LABOR Tractors hour 7.50 1.5934 11.95 _________ Self-Propelled Eq. hour 7.50 0.3800 2.85 _________IRRIGATION LABOR Irrig sys 9 fl WP hour 7.50 0.3150 2.36 _________OWNER LABOR Self-Propelled Eq. hour 12.00 0.4180 5.02 _________DIESEL FUEL Tractors gal 0.74 9.4218 6.97 _________ Self-Propelled Eq. gal 0.74 2.6980 2.00 _________ Irrig sys 9 fl WP gal 0.74 77.9450 57.68 _________GASOLINE Self-Propelled Eq. gal 1.17 1.9000 2.22 _________REPAIR & MAINTENANCE Implements acre 3.04 1.0000 3.04 _________ Tractors acre 8.89 1.0000 8.89 _________ Self-Propelled Eq. acre 12.78 1.0000 12.78 _________ Irrig sys 9 fl WP acin 0.16 35.0000 5.46 _________INTEREST ON OP. CAP. acre 11.23 1.0000 11.23 _________

————TOTAL DIRECT EXPENSES 379.43 _________RETURNS ABOVE DIRECT EXPENSES 96.73 _________

FIXED EXPENSES Implements acre 5.37 1.0000 5.37 _________ Tractors acre 12.72 1.0000 12.72 _________ Self-Propelled Eq. acre 27.40 1.0000 27.40 _________ Irrig sys 9 fl WP acre 32.07 1.0000 32.07 _________

————TOTAL FIXED EXPENSES 77.55 _________

————TOTAL SPECIFIED EXPENSES 456.98 _________RETURNS ABOVE TOTAL SPECIFIED EXPENSES 19.18 _________

ALLOCATED COST ITEMS Overhead (owner) acre 64.31 1.0000 64.31 _________

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L&W, SWWP Conv. Riced/ acre 29.00 1.0000 29.00 _________RESIDUAL RETURNS -74.13 _________

_______________________________________________________________________a/ Includes estimated market income only.b/ Prorated use based on survey results of percentage of rice acreage actually treated in 1991 and

expert opinion of these percentages in more recent years.c/ Drying cost charged on green weight.d/ This charge represents net income to a land/water lord based on budgets applicable to a tenant

version of the above budget, incorporating relevant cost share items, and may be interpretedas an opportunity cost to an owner/operator. It does not represent an estimated cost ofland.

Table 16. Estimated costs and returns per acre. Rice, water planted,Table 16. Estimated costs and returns per acre. Rice, water planted,Table 16. Estimated costs and returns per acre. Rice, water planted,Table 16. Estimated costs and returns per acre. Rice, water planted,Table 16. Estimated costs and returns per acre. Rice, water planted,tenant-operators, Southwest Louisiana, 1998.tenant-operators, Southwest Louisiana, 1998.tenant-operators, Southwest Louisiana, 1998.tenant-operators, Southwest Louisiana, 1998.tenant-operators, Southwest Louisiana, 1998.

_______________________________________________________________________Item Unit Price Quantity Amount Your Farm_______________________________________________________________________

dollars dollarsINCOMEa/

Rice cwt 10.00 48.0000 480.00 _________ Land share rent cwt 10.00 -9.6000 -96.00 _________ Water share rent cwt 10.00 -9.6000 -96.00 _________ Rice checkoff cwt 0.08 -28.8000 -2.30 _________

————TOTAL INCOME 285.70 _________

DIRECT EXPENSES CUSTOM Fertilizer Truck acre 3.50 1.0000 3.50 _________ Airplane seed cwt 4.55 1.4000 6.37 _________ Global Pos. System acre 0.45 6.3500 2.86 _________ Airplane Stam acre 5.15 2.0000 10.30 _________ Airplane furadanb/ acre 4.00 0.5200 2.08 _________ Airplane 2,4-D acre 5.10 1.0000 5.10 _________ Airplane Fert cwt 4.05 1.4000 5.67 _________ Airplane benlateb/ acre 4.50 0.7000 3.15 _________ Airplane Insectb/ acre 3.95 0.1300 0.51 _________ Drying Ricec/ cwt 0.95 32.3580 30.74 _________ Storage Rice cwt 0.40 28.8000 11.52 _________FERTILIZER Nitrogen lbs 0.23 72.0000 16.56 _________ Phosphate lbs 0.26 30.6000 7.96 _________ Potash lbs 0.14 30.6000 4.28 _________FUNGICIDES Quadrisb/ oz. 2.19 2.5200 5.52 _________ Benlate 50% WPb/ lbs 16.50 0.2100 3.47 _________HERBICIDES Stam M4 qt 4.58 3.6000 16.49 _________ 2,4-D-LV4 pt 1.78 0.6000 1.07 _________

106106106106106

HIRED LABOR Other labor hour 7.50 1.0000 7.50 _________INSECTICIDES Furadan 3Gb/ lbs 0.80 5.3040 4.24 _________ Methyl pt 3.31 0.0780 0.26 _________ parathion 4Eb/

OTHER Plastic sqft 0.08 13.5000 1.08 _________SEED Rice seed lbs 0.21 140.0000 28.70 _________OPERATOR LABOR Tractors hour 7.50 1.5934 11.95 _________ Self-Propelled Eq. hour 7.50 0.3800 2.85 _________IRRIGATION LABOR Irrig. sys. 10 fl WP hour 7.50 0.3150 2.36 _________OWNER LABOR Self-Propelled Eq. hour 12.00 0.4180 5.02 _________DIESEL FUEL Tractors gal 0.74 9.4218 6.97 _________ Self-Propelled Eq. gal 0.74 2.6980 2.00 _________GASOLINE Self-Propelled Eq. gal 1.17 1.9000 2.22 _________REPAIR & MAINTENANCE Implements acre 3.04 1.0000 3.04 _________ Tractors acre 8.89 1.0000 8.89 _________ Self-Propelled Eq. acre 12.78 1.0000 12.78 _________ Irrig. sys. 10 fl WPacin 0.16 35.0000 5.46 _________INTEREST ON acre 7.58 1.0000 7.58 _________ OP. CAP. ————TOTAL DIRECT EXPENSES 250.04 _________RETURNS ABOVE DIRECT EXPENSES 35.66 _________

FIXED EXPENSES Implements acre 5.37 1.0000 5.37 _________ Tractors acre 12.72 1.0000 12.72 _________ Self-Propelled Eq. acre 27.40 1.0000 27.40 _________

————TOTAL FIXED EXPENSES 45.48 _________

————TOTAL SPECIFIED EXPENSES 295.52 _________RETURNS ABOVE TOTAL SPECIFIED EXPENSES -9.82 _________

ALLOCATED COST ITEMS Overhead (tenant) acre 53.29 1.0000 53.29 _________RESIDUAL RETURNS -63.11________________________________________________________________________________*Assumes a 1/5 crop share for land and a 1/5 crop share for water with landlord and waterlordeach paying 1/5 of fertilizer, chemicals, drying and storage costs, and the waterlord paying allirrigation fuel costs.a/ Includes estimated market income only.b/ Prorated use based on survey results of percentage of rice acreage actually treated in 1991and expert opinion of these percentages in recent years.c/ Drying cost charged on green weight.

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Table 17. U.S. Supply and Use of Rice, Selected Years. Item 1990/91 1991/92 1992/93 1993/94 1994/95 1995/96 ————Million Cwt. of Rough Rice Equivalent———— Production 156.1 159.4 179.7 156.1 97.8 174.2 Supply 187.2 189.3 213.2 202.5 230.9 213.9 Total Domestic 91.6 95.4 96.7 101.5 98.6 104.2 Use and Residual Food 63.767.1 69.0 71.2 74.0 77.0 Seed 3.6 3.9 3.6 4.2 4.1 4.1 Brewers 15.3 15.4 15.1 15.1 15.1 15.1 Exports 71.0 66.4 77.0 75.2 100.9 86.0 Total Use 162.6 161.8 173.7 76.7 199.5 190.2 Ending Stocks 24.6 27.5 39.5 25.8 31.4 23.7

———————Units as Specified——————-———— Area Harvested 2.82 2.88 3.18 2.92 3.35 3.12 (mil. acres) Yield (cwt./acre) 55.29 57.31 57.36 55.1 59.64 56.35 Avg. Market Price 6.68 7.58 5.89 7.98 6.78 7.00-8.00 ($/cwt.) Per Capita Consumption Food and Brewers (lbs. - rough equiv.)31.92 32.18 33.18 33.66 34.41 35.26

*Source: Rice Outlook and Situation Yearbook and various other USDA publications.

Figure 111. Rice Milling Process for 100 Pounds of Rough Rice

Source: Rice Miller’ Association, (Arlington, Virginia)

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Table 18. Selected World Rice Production and Trade Data, 1997/98Table 18. Selected World Rice Production and Trade Data, 1997/98Table 18. Selected World Rice Production and Trade Data, 1997/98Table 18. Selected World Rice Production and Trade Data, 1997/98Table 18. Selected World Rice Production and Trade Data, 1997/98

Country Productiona/ Exportsb/ Importsb/

(mmt) (tmt) (tmt)

Bangladesh 27.8 —— 100 Burma 16.6 100 —— China 195.7 1000 1000 India 122.3 1750 —— Indonesia 51.2 0 1500 Japan 12.4 —— 650 Philippines 11.2 —— 1000 South Korea 7.4 —— —— Pakistan 6.5 1700 —— Thailand 21.2 5250 —— Vietnam 27.3 3500 —— Selected Asian Country Sub-Totals 499.4 13300 4250 Australia 1.2 650 —— Brazil 9.6 —— 1000 EC-12 2.5 350 700 Iran —— —— 1250 Saudi Arabia —— —— 700 Senegal —— —— 500 South Africa —— —— 500 All Others 46.5 2106 10306 Total Non-U.S. 559.1 16406 19206 United States 8.2 2800 —— World Total 567.3 19206 19206

a/ Production on Million Metric Tons, Rough Rice Equivalentb/ Imports and Exports on Thousand Metric Tons, Milled Rice Equivalent

Exports and Imports Projected for Calendar Year 1998.** A dashed line indicates this country was not counted independently of other.*** Source: Rice Outlook and Situation Yearbook and various other USDA publications.****Totals may not add due to rounding procedures.

Table 19. Selected U.S. Rice Industry Data, 1993 Through 1997 Crop Year

1993 1994 1995 1996 1997———————(Dollars per Cwt.—————

Target Price per cwt. of 10.71 10.71 10.71 — — Rough Rice Price Support Loan per cwt. 6.50 6.50 6.50 6.50 6.50 of Rough rice U.S. Average Rough Rice Price 7.98 6.78 9.15 9.90 9.75 per cwt. (12 months) Deficiency Payments per cwt 3.98 3.79 3.22 — — of Rough Rice Loan and Purchase Rates per cwt. Projected Milled Rice as Determined by Official Test: Long Grain Variety Head Rice 10.75 10.72 10.69 10.77 10.69 Medium & Short Grain Variety Head rice 9.75 9.72 9.69 9.77 9.69 Brokens (second heads, screenings and brewers) 5.37 5.36 5.35 5.35 5.35

*Source: Rice Situation and Outlook Yearbook and other USDA publications.

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Table 20. Rice Provisions of the Federal Agriculture Improvement andTable 20. Rice Provisions of the Federal Agriculture Improvement andTable 20. Rice Provisions of the Federal Agriculture Improvement andTable 20. Rice Provisions of the Federal Agriculture Improvement andTable 20. Rice Provisions of the Federal Agriculture Improvement andReform Act of 1996.Reform Act of 1996.Reform Act of 1996.Reform Act of 1996.Reform Act of 1996.

Contract Payments: • Eligible producers can enter into seven-year market transition contracts for 1996-2002.• Guaranteed direct fixed payments not tied to market prices. Target prices and deficiency payments are

eliminated.• Payments received on 85% of eligible base acreage

and is based on historical program yield .• Projected rice payments per unit on paid base acreage:

(Dollars/cwt.)1996 - $2.75/cwt1997 - $2.71/cwt1998 - $2.94/cwt1999 - $2.81/cwt2000 - $2.58/cwt2001 - $2.09/cwt2002 - $2.03/cwt

Loan Provisions: • Establishes a loan rate for rice at $6.50/cwt.• Extends marketing loan provisions for rice with repayment at a lower rate if world prices are below loan rate.

Planting Flexibility: • No minimum program crop planting requirements.• Triple base provisions of 1990 farm bill are eliminated• Producers are free to plant any program crop or

oilseed crop on rice base acreage without restriction.• Fruits and vegetables planting prohibited on 85% of base eligible for payment. No restrictions on remaining 15% of base.• Haying and grazing are permitted on payment acreage during the five principal growing months.• All acreage reduction programs (ARP) eliminated.

Payment Limitations: • Current payment limitation on direct payments reduced from $50,000 to $40,000.• Extends limit on marketing loan gains and loan deficiency payments at $75,000.• Extends three-entity provisions.

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Glossary

Active ingredient (ai) - Component of a pesticide that has toxic activity against thepest in contrast to the inert or inactive ingredients.

Adventitious - Refers to a structure arising from an unusual place, such as roots grow-ing from stems or leaves.

Amylographic - Spectrographic analysis of starch.Amylose - Type of starch in rice grain; higher content makes rice cook drier.Anaerobic - Refers to an organism able to live and grow without air or free oxygen.Antagonistic - Decreased activity of an organism from the effect of another organism

or compound.Bacterium (pl. bacteria) - A one-celled microscopic organism that lacks chlorophyll

and multiplies by fission (splitting apart).Biological control - Disease control by means of predators, parasites, competitive

microorganisms and decomposing plant material, which restrict or reduce the popula-tion of the pathogen.

Biotype - Genetic varient of a species.Boot - Growth stage of rice when the panicle is more than 1 inch long but before

emergence (heading).Brewers - Smallest size of broken milled rice, which is less than one-quarter of the

whole kernel.Broken yield - Pounds of broken grain milled from 100 pounds of rough rice (total

milling yield - head milling yield).Brokens - Milled rice kernels which are smaller than three-fourths of the whole kernel.

This includes second heads, screening and brewers.Brown rice - Rice with only the hulls removed.Carbohydrate - A class of organic chemicals composed of carbon, hydrogen and

oxygen; in plants, photosynthesis-produced sugars and starch are examples.Chevrons - Stripe-like pattern consisting of several curved or V-shaped bands.Chlorophyll - Green pigment associated with photosynthesis.Chlorosis - Yellowing of normally green tissue caused by the destruction of the chloro-

phyll or the partial failure of the chlorophyll to develop.Coalesce - The coming together of two or more lesions to form a large spot or blotch.Coleoptile - The protective covering of an emerging shoot, is not a true leaf.Commingled rice - Rice which has been blended with other rice of similar grain type,

quality and grade.Conidiophore - Specialized hypha bearing conidia.Conidium (pl. conidia) - A spore formed asexually, usually at the top or side of a

specialized hypha (conidiophore).Crown - Junction between stem and root.Culm - The jointed stem of grass.Damage - Economic loss to a crop caused by an insect.Debris - The crop residues left from the previous crop.Denitrification - Conversion of nitrate nitrogen to gaseous nitrogen.Dough - The stage when the endosperm of the grain has begun to solidify.Drift - The spread of airborne spray droplets to adjacent, non-target areas.Drying - Removal of kernel moisture to obtain a safe storage condition (about 12.5

percent moisture). Drying is achieved by forcing heated air through grain mass.Economic injury level - The lowest pest density that will cause damage equal to the

cost of control.Economic threshold - The density of a pest at which control action must be taken to

prevent a pest from reaching the economic injury level.

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Embryo - The microscopically small plant under the lemma near the point of attach-ment of the rice seed to the panicle.

Endemic - The normal presence of a pest in a crop year after year in less than epi-demic amounts.

Endosperm - Primarily carbohydrate in the form of starch comprising most of the riceseed and used during germination and early plant growth.

Enzyme - Protein specialized to catalyze chemical reactions related to metabolic activitynecessary for growth.

EPA - Environmental Protection Agency, an agency of the U.S. government.Epiphytotic or epidemic - The extensive development of a disease in a geographical

area.Fissuring - The cracking or breaking of grains prior to harvest caused by alternating

periods of wetting and drying.Flag leaf - The uppermost leaf of the rice plant, immediately below the panicle.Floret - The rice flower including the lemma, palea and reproductive floral parts.Flush - Flooding of the field with drainage soon after for the purpose of keeping the

seed bed moist.Foliar - Dealing with the foliage of a plant.Fungus (pl. fungi) - An undifferentiated plant lacking chlorophyll and conductive

tissues.Gelatinization temperature - Index to classify the cooking types of long, medium and

short grain.Gibberellic acid (GA) - Plant growth hormone which stimulates elongation.Green rice - Rough rice from which the excess moisture has not been removed (usu-

ally 18.5 percent to 22.5 percent moisture).Green ring - Rice plant growth stage during which the tissue of the first internode

appears green because of the accumulation of chlorophyll, indicates a change fromvegetative to reproductive growth.

GPA - Gallons per acre.Heading - The period during which panicles exert from the flag leaf sheath.Head rice - Milled rice kernels which are more than three-fourths of the whole kernel.Head milling yield - Pounds of head rice milled from 100 pounds of rough rice.Horizontal resistance - A uniform resistance against all races of a pathogen. The level

of resistance is usually only moderate and often influenced by temperature.Hulling - A process of removing husks from rough rice.Hulls - Outer husk of the rice grain, usually a waste product, but can be used in rice

millfeed and as a filler for feed products.Hydrophobic - Resistant to wetting.Hypha (pl. hyphae) - A single thread or filament of a fungus.Imbibed - Absorption of water.Infestation level - Percent of the population affected by a pathogen, or density of a

pest in a unit area.Inflorescence - A flower cluster.Injury - Feeding by an insect on a crop but not necessarily causing economic loss.Instant rice - Milled rice which is cooked, cooled and dried under controlled conditions

and packaged in a dehydrated form. Before packaging, it is enriched with thiamine,riboflavin, niacin and iron.

Instar - The stage of an insect between molts.Internode - The tissue of a rice stem between two nodes (joints).Internode elongation - Jointing, the rapid lengthening of the tissue between nodes of

a rice stem.IPM - Integrated pest management; the reduction of plant pests through the combined

use of various control practices.

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Joint - A node.Key pest - A pest that causes economic loss in most years.Label - Document accompanying a pesticide container giving specific information about

a pesticide, also a legal document specifying how and when a product can be used.Larva - The second stage of insects with complete metamorphosis (egg, larva, pupa,

adult). Larvae look different from adults, live in different places and feed on differ-ent food.

Lemma - The larger of two enclosing structures which form the hard outer covering ofa rice seed.

Lesion - A localized area of diseased tissue of a host plant.Lodging - The leaning or falling over of rice plants before harvest.Long-grain rice - Rice that is long and slender, measuring one-quarter of an inch or

more in length. Kernel size is 6.5 mm or more long, and the length-width ratio isfrom 3.27 to 3.41:1.

Main shoot - The first noticeable above-ground portion of a rice plant originatingdirectly from the seed.

Medium-grain rice - Rice that is plump, measuring less than one-quarter of an inchlong. Kernel size is from 5.37 to 6.06 mm and has a length-width ratio of from 2.09 to2.49:1.

Mesocotyl - Portion of the shoot between the seed and the cotyledon.Metamorphosis - A change in form during development.Milk - The stage when the endosperm of the grain is the consistency of milk.Milled rice - Rice grain from which husks, bran and germ have been removed.Milling - Processing the rough rice into milled or brown rice.Mycelium (pl. mycelia) - A mass of fungus hyphae; the vegetative body of a fungus.Neck - Region of the head consisting of the joint below the panicle.Necrotic - dead.Nematode - Generally microscopic, unsegmented roundworm, usually threadlike, free-

living or a parasite of plants or animals.Node - The pronounced area of a rice stem from which a leaf originates.Nymph - The immature stage of insects with incomplete metamorphosis (egg, nymph,

adult). Nymphs look similar to adults, live in the same place as adults and feed on thesame food.

Occasional pest - A pest that occasionally causes economic loss.Overwinter - A term used to describe an insect’s ability to survive the winter. The

overwintering stage and site are important.Palea - The smaller of two enclosing structures which form the hard outer covering of a

rice seed.Panicle - The main axis (which is branched) of an inflorescence.Panicle 2mm - Same as panicle differentiation.Panicle differentiation (PD) - Rice plant growth stage during which the panicle is

recognizable as a small tuft of fuzz about 2 mm (1/8 inch) long.Panicle initiation (PI) - Rice plant growth stage during which a specialized group of

cells in the growing point begin to actively divide. It often corresponds to or closelyfollows green ring and can be positively identified only with magnification.

Parboiled rice - Rough rice soaked in warm water under pressure, steamed and driedbefore milling.

Parboiling - A process by which rough rice is steeped in water, steamed or heated togelatinize starch, then subsequently dried.

Pathogen - A specific agent that causes infectious disease.Pest - An organism that competes with humans.pH - A measure of the acidity or alkalinity of soil, water or solution. Values range from

0 to 14 with 7 being neutral, less than 7 acidic and above 7 alkaline.

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Photosynthesis - The process by which plants absorb light and use the energy forgrowth and development.

Phytotoxic - Causes toxic or harmful effects on a plant.Pollination - Transfer of pollen from the male to female flower structures.Precooked rice - Milled rice which has been processed by various methods to make it

cook quickly.Processed rice - Rice used in breakfast cereals, soups, baby foods and packaged

mixes.Pupa - The third stage of insects with complete metamorphosis (egg, larva, pupa,

adult). Pupae do not feed and are in a resting stage.Radicle - First root of a germinating seed.Ratoon crop (second crop) - Regrowth of rice from the stalks harvested earlier.Resistance - The inherent ability of a host plant to suppress, retard or prevent entry or

subsequent activity of a pathogen or other injurious factor.Rice bran - Layer directly beneath the hull containing the outer bran layer and parts of

the germ. Bran is rich in protein and vitamin B. It is used as livestock feed andvitamin concentrates.

Rice polish - A layer removed in the final stages of milling which was composed ofthe inner white bran. It is rich in protein and has high fat content; used in livestockfeed and baby food.

Rough rice (paddy) - Rice grains with the hulls, but without any part of stalk; consistsof 50 percent or more of paddy kernels (whole or broken unhulled kernels of rice).

Saturated - Condition when all soil pore spaces are full of water.Sclerotium (pl. sclerotia) - Dense, compacted mass of hyphae, resistant to unfavor-

able conditions and can remain dormant for long periods; able to germinate whenfavorable conditions return.

Screenings - Broken milled rice which is less than one-half of the whole kernel andmore than one-quarter of the whole kernel.

Second heads - Largest size of broken milled rice which is more than one-half of thewhole kernel size.

Semidwarfs - Plants changed genetically to a reduced plant height.Senescence - The process of aging leading to death after the completion of growth in

plants and individual plant parts.Shoot - A collection of leaves originating from a crown in rice before stem formation

occurs.Short-grain rice - Rice that is almost round. Kernel size ranges from 4.56 to 5.01 mm

in length, and the length-width ratio varies from 1.66 to 1.77:1.Skipper - A group of insects closely related to moths and butterflies. Adult skippers

have knobs on the end of their antennae (similar to butterflies), and the antennae arewidely spaced on the head (similar to moths).

Spikelet - Consists of a single floret below which are two reduced bracts.Spore - A minute propagative unit that functions as a seed, but differs from it in that a

spore does not contain a preformed embryo.Stale seedbed - Seedbed prepared about planting time in which vegetation is allowed

to grow usually.Stooling - Tillering.Straighthead - Physiological disorder characterized by sterile, deformed seeds and an

upright seedhead.Sun checking - Fissuring.Susceptibility - The inability of a plant to resist the effect of a pathogen or other

damaging factor.Suppression - The act of reducing or holding back rather than eliminating.Tiger moth - A group of moths with hairy caterpillars (the woollybear).

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Tiller - A young vegetative shoot arising from nodes at the base of the plant; most canproduce a panicle.

Tillering - The period during which tillers are formed, usually beginning at the 4- to 5-leaf stage and continuing until early reproductive growth.

Tolerance - Amount of pesticide that can safely remain in or on raw farm products attime of sale, or the ability of a plant to yield equally under diseased condition ashealthy.

Total milling yield - Pounds of head, brewers, second heads and screenings milledfrom 100 pounds of rough rice.

White rice - Total milled rice after the hulls, bran layer and germ are removed. Thisincludes head rice and brokens.

Y-leaf - The most recently expanded leaf, at least 3/4 unfurled. This leaf is usuallyselected for tissue analysis.

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CONTRIBUTING AUTHORS

Clayton A. Hollier, Specialist (Plant Pathology), Louisiana Cooperative Extension Service, BatonRouge, and Editor.

James Barbour, Assistant Professor (Entomology), University of Idaho (formerly with the LouisianaAgricultural Experiment Station, Department of Entomology, Baton Rouge).

Patrick K. Bollich, Professor (Agronomy), Louisiana Agricultural Experiment Station, Rice ResearchStation, Crowley.

Douglas L. Deason, Specialist (Agricultural Engineering), Louisiana Cooperative Extension Service,Baton Rouge.

Richard T. Dunand, Professor (Plant Physiology), Louisiana Agricultural Experiment Station, RiceResearch Station, Crowley.

James F. Fowler, Specialist (Wildlife), Louisiana Cooperative Extension Service, Baton Rouge.

Eddie R. Funderburg, Specialist (Agronomy), Louisiana Cooperative Extension Service, Baton Rouge.

G. Grant Giesler, Research Associate (Agricultural Economics), Louisiana Agricultural ExperimentStation, Department of Agricultural Economics, Baton Rouge.

Donald E. Groth, Professor (Plant Pathology), Louisiana Agricultural Experiment Station, RiceResearch Station, Crowley.

William A. Hadden, Specialist (Agricultural Engineering), Louisiana Cooperative Extension Service,Baton Rouge.

Farman L. Jodari, Assistant Professor (Agronomy), Louisiana Agricultural Experiment Station, RiceResearch Station, Crowley.

L. Eugene Johnson, Specialist (Agricultural Economics), Louisiana Cooperative Extension Service,Baton Rouge.

David Jordan, Assistant Professor (Weed Science), North Carolina State University (formerly with theLouisiana Agricultural Experiment Station, Northeast Louisiana Research Station, St. Joseph).

Steven D. Linscombe, Professor (Agronomy), Louisiana Agricultural Experiment Station, RiceResearch Station, Crowley.

Kent S. McKenzie, Rice Breeder, Rice Research Station, Biggs, CA (formerly an agronomist with theLouisiana Agricultural Experiment Station, Rice Research Station, Crowley).

Mark Muegge, Assistant Professor (Entomology), Texas A&M University (formerly a postdoctoralassociate, Department of Entomology, Baton Rouge).

Joseph A. Musick, Resident Director of the Rice Research Station and Professor (AgriculturalEconomics), Louisiana Agricultural Experiment Station, Crowley.

James H. Oard, Associate Professor (Agronomy), Louisiana Agricultural Experiment Station,Department of Agronomy, Baton Rouge.

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William C. Rice, Insect Pathologist, USDA/ARS, Rice Research Station, Crowley.

Dennis R. Ring, Associate Specialist (Entomology), Louisiana Cooperative Extension Service, BatonRouge.

Milton C. Rush, Professor (Plant Pathology), Louisiana Agricultural Experiment Station, Departmentof Plant Pathology and Crop Physiology, Baton Rouge.

John K. Saichuk, Associate Specialist (Agronomy), Louisiana Cooperative Extension Service, RiceResearch Station, Crowley.

Michael E. Salassi, Associate Professor (Agricultural Economics), Louisiana Agricultural ExperimentStation, Department of Agricultural Economics, Baton Rouge.

Dearl E. Sanders, Specialist (Weed Science), Louisiana Cooperative Extension Service, Baton Rouge.

K. Paul Seilhan, formerly Coordinator, Rice Educational Programs (Agronomy), LouisianaCooperative Extension Service, Baton Rouge.

Michael Stout, Assistant Professor (Entomology), Louisiana Agricultural Experiment Station,Department of Entomology, Baton Rouge.

Lawrence M. White III, Research Associate/Coordinator (Rice Foundation Seed Program), LouisianaAgricultural Experiment Station, Rice Research Station, Crowley.

Visit our website @ http://wwwagctr.lsu.edu/wwwac

Louisiana State University Agricultural Center, William B. Richardson, Chancellor

Louisiana Cooperative Extension Service, Jack L. Bagent, Vice Chancellor and Director

Pub. 2321 (7 M) Rev.11/98

Issued in furtherance of Cooperative Extension work, Acts of Congress of May 8 and June 30, 1914, in

cooperation with the United States Department of Agriculture. The Louisiana Cooperative Extension Service

provides equal opportunities in programs and employment.