No. 8 June 22, 2006 - North Dakota State University · Winged aphids were present. ... necessarily...

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No. 8 June 22, 2006

Inside this Issue...2006 Project Safe Send Collection Sites . . . . . . . . . . . . 1Begin Scouting for Soybean Aphids . . . . . . . . . . . . . . . 1Grasshopper Activity Increasing . . . . . . . . . . . . . . . . . . 2Canola Insect Pest Trap Network . . . . . . . . . . . . . . . . . 2Degree Days for Collecting Leafy Spurge Flea Beetles . 2White Heads in Wheat - Wheat Stem Maggot . . . . . . . . 3Oilseed Sunflower Development . . . . . . . . . . . . . . . . . . 3Soybean Flowering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Facts about Tillering in Corn . . . . . . . . . . . . . . . . . . . . . 4Wheat Streak Mosaic Virus Update . . . . . . . . . . . . . . . . 5Wheat Disease Observations, June 12-20 . . . . . . . . . . . 5NDSU Disease Forecasting Site . . . . . . . . . . . . . . . . . . . 5Keep Aware of Soybean Cyst Nematode . . . . . . . . . . . . 6Sclerotinia Risk Map for Canola . . . . . . . . . . . . . . . . . . 6Glyphosate Price Quiz . . . . . . . . . . . . . . . . . . . . . . . . . . 6What is this Weed - Wild Strawberry . . . . . . . . . . . . . . . 7ND Petitions Being Submitted to EPA . . . . . . . . . . . . . . 7Crop Rotation Restrictions . . . . . . . . . . . . . . . . . . . . . . . 7Yellowheaded Spruce Sawfly Update . . . . . . . . . . . . . . 8Plant Diagnostic Lab Summary . . . . . . . . . . . . . . . . . . 10Around the State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2006 PROJECT SAFE SEND COLLECTION SITES,DATES ANNOUNCED

Sixteen sites have been selected for the 2006 ProjectSafe Send collection of unusable pesticides, scheduled forJuly 11-25.

“This is a good time for anyone with pesticides –farmers, ranchers, chemical dealers and applicators,government agencies and homeowners – to take stock oftheir inventory and set aside unusable pesticides fordisposal,” said Agriculture Commissioner Roger Johnson.“With 16 collection sites, no one will have to drive far toget rid of their waste pesticides, safely, efficiently and atno charge.”

The collections have been scheduled for thefollowing dates and communities:

July 11-12 West FargoJuly 13 MayvilleJuly 14 DraytonJuly 17 Courtenay and MinotJuly 18 Minot and LangdonJuly 19 Bottineau and TiogaJuly 20 Rugby and KilldeerJuly 21 Linton and BelfieldJuly 24 Edgeley and HettingerJuly 25 Wyndmere and Glen Ullin

Persons with more than 1,000 pounds of pesticidesshould call (701) 328-4997 to pre-register. No other pre-registration is required.

Pesticide rinse water will also be accepted at any ofthe 16 collection sites. The first 100 pounds of rinse waterwill be taken free of charge; a fee of $1 per pound will becharged for each additional pound.

Since 1992, nearly 5,000 participants have usedProject Safe Send to safely get rid of almost 1.8 millionpounds of unusable pesticides, including DDT, arsenicand mercury compounds.

Project Safe Send is funded through the fees paid bypesticide manufacturers to register their products in NorthDakota.

For more information, please call Patrice Lahlum or TedQuanrud at (701) 328-2231.

BEGIN SCOUTING FOR SOYBEAN APHIDSThe first soybean aphid was detected on June 15,

2006 in northeastern North Dakota. Low levels ofsoybean aphids have been observed in soybean fields inthe southeast (Cass, Richland, Traill counties), andnortheast regions (Walsh, Grand Forks, and Nelsoncounties) of North Dakota from June 15-20, 2006.Average numbers of aphids are very low about <5 aphidsper plant with a high of 40 aphids per plant. Wingedaphids were present. Crop stages of soybeans are still inthe early vegetative stages (VC to V3) crop stages. TheMulticolored Asian lady beetle (Harmonia axyridis), apredator of soybean aphids, was also observed in soybeanfields.

Begin scouting fields at the V3 to V4 stage todetermine if soybean aphids are present in fields. Checknumerous locations within a field for aphids as theirdistribution is often spotty throughout a field. Notreatment is recommended at this time and is discouragedso insecticides do not reduce the presence of predatorsand parasites. Early detection of soybean aphids does notnecessarily mean that we will have high populations ofaphids this year. It does mean that we need to be vigilanton scouting for soybean aphids. Stay tune for moreupdates and information on treatment thresholds.

North Dakota State University CROP & PEST REPORT June 22, 2006

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GRASSHOPPER ACTIVITY INCREASING Continue monitoring the field edges and entire fields

of agricultural crops for young grasshopper nymphs.There has been a few reports of increased grasshopperhatching / activity in north central region. Grasshoppersare more easily and economically controlled while theyare in the nymph stage and still within hatching sites, suchas roadsides and fencerows. The warm spring is causingan earlier hatch and more rapid development. The rainfallhas been sporadic throughout North Dakota. Under thesehot dry conditions, a small grasshopper can do as muchdamage as a large grasshopper under cool, wet conditions.

CANOLA INSECT PEST TRAP NETWORK A trap network is being coordinated through the

NDSU IPM Survey Program for diamondback moth andbertha armyworm in canola this year. Trap catches fordiamondback moth are VERY LOW and pose NOTHREAT to canola crop so far. The trap catches rangefrom 0 to 18 moths per trap week for this past weekthroughout the southwest, north central and northeastregions of North Dakota. No report for bertha armyworm.

DEGREE DAYS FOR COLLECTING LEAFYSPURGE FLEA BEETLES

There has been several questions about how manydegree days are required for collecting leafy spurge fleabeetles. The accumulated growing degree days (AGDD)for sunflower (base of 44F) can be used as a guide todetermine when to begin scouting for adult flea beetles.Begin scouting for adult flea beetles when the AGDDapproaches 1,000. Likewise, the flea beetle populationand egg laying by females begins to decline when theAGDD reaches 1,600 or more.

Collect flea beetles between 1,200 and the 1,600AGDD. Peak emergence of Aphthona spp. flea beetlesalso corresponds to the flowering of the prairie wild roseand the ripening of garden strawberries in North Dakota.See current map of AGDD in North Dakota. Use thesunflower degree days/growth stage application inNDAWN and enter “2006-03-01” for planting date andselect “degree day” for map type.

http://ndawn.ndsu.nodak.edu/sunflowerdd-form.html


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WHITE HEADS IN WHEAT - WHEAT STEMMAGGOT

White heads have been reported in winter wheat insouthwest regions of North Dakota. This is from feedinginjury caused by the larvae of wheat stem maggot (a fly).The wheat stem maggot damage becomes evident afterflowering when seeds begin to develop. Normally the firstindication of its presence is the dying and whitening of thewheat heads (see photo) and upper internodes while thelower stem and leaves remain green. A single maggot willbe found inside the straw just above the last node. Theplant stem pulls out very easily and if larvae are notfound, the stem is usually cut off. The presence of whiteheads alone is not always an accurate assessment ofdamage. The maggots can also infest young tillers prior tothe boot stage causing the affected tiller to abort. Theseaborted tillers can account for an unseen loss in yield.Little is known about this insect pest, and no chemicalcontrols are recommended. Two diseases can also causewhite heads are scab and root rot.

Janet KnodelExtension [email protected]

OILSEED SUNFLOWER DEVELOPMENTSunflower growth and development responds to heat

units similar to corn and several other crops. The basetemperature of 44 F is used to determine Growing DegreeDays (GDD). GDD formula = [(daily maximumtemperature + daily minimum temperature)/2] - 44 F.

In the table below research data was collected at theCarrington Research and Extension Center over a numberof years on sunflower stage development and heat units.

Oil sunflower development by days and growingdegree day (GDD) units, 1994-95, CarringtonResearch Extension Center*

Sun-flowerstage

Average days andGDD units increasefrom previous stage

Average days andGDD units

accumulated fromplanting

days units days unitsVE 10 167 10 167V4 10 182 20 349V8 8 196 28 545V12 6 145 34 690V16 5 82 38 772V20 6 99 44 871R1 2 49 46 919R2 15 333 61 1252R3 6 142 67 1394R4 4 99 71 1492R5.1 3 54 73 1546R5.5 4 77 77 1623R6 8 158 84 1780R7 12 272 96 2052R8 9 159 104 2211R9 15 259 119 2470

Growing Degree Days were averaged over 5 hybridseach year and 5 plants per hybrid per plot were observed. Sunflower was planted on May 25 and May 23 in 1994and 1995 respectively.

GDD units/data for 2006 can be found on NDSU’sExtension site under Ag weather (NDAWN).http://ndawn.ndsu.nodak.edu/applications.html Just clickon the applications section and then to "Degree Days".


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SOYBEAN FLOWERINGThe appearance of flowers on soybean plants is

controlled by a complicated interaction betweenphotoperiod (length of light period) and temperature, withtemperature being more important in the northern soybeanbelt and photoperiod being more important in the southernsoybean belt. Nearly all soybean varieties are stimulatedto flower by decreasing photoperiod length (short-dayplants). In nature, decreasing photoperiods occur afterJune 21. Because of the sensitivity of soybean tophotoperiod and temperature, soybean varieties aregrouped into maturity group bands. These bands are about100- to 150-miles wide and are somewhat parallel (but notexactly) to Earth's latitudes. In general, soybean varietiesplanted south of their adapted maturity group will flowermore quickly, and plants will be shorter than normal. Thisoften decreases yield potential.

The first flower on soybean plants with anindeterminate growth habit (type in ND and MN) isinitiated at R1 on the third to the sixth main stem nodeand proceeds upward and downward. The coteledonarynode, the unifoliolate leaf nodes and the first twotrifoliolate nodes are initiated in the seed, so their buds arevegetative. Flowering proceeds toward the top of the plantand continues as vegetative growth proceeds. Theflowering period is usually 20 to 30 days. Nodes higherand lower than this quickly produce flowers, so within afew days all nodes possess flowers. By the R5 stage theplant has completed most of its flowering but a few newlyopened flowers may be present on branches and in theupper stem nodes. Almost all soybean flowers pollinatebefore opening. Therefore little if any pollen drift does orwill occur. High temperatures and droughty growingconditions can have an influence on flower abortion andless pod and seed set. Also application of certainherbicides at this flowering stage can cause pods to abort. One must always check the label to insure that it’s safe toapply a herbicide if the soybeans are flowering.

Three to four days following flower opening, theflower petals will dry and the pod begins to elongate. Two and a half weeks after the flower opens the fulllength pod will have been formed. Pod growth is mostrapid between the R4 to R5 growth stages.

Duane R. BerglundNDSU Extension Agronomist

[email protected]

FACTS ABOUT TILLERING IN CORNThere have been numerous reports of tillering in corn

this past week. In my own plots I have noted thedevelopment of tillers on nearly every plant on somehybrids. The following are some basic facts abouttillering in corn.• Tiller production in corn is much less common than

in small grains. Nevertheless, corn tillers result fromnormal physiological development processes similarto those in small grains. All basal nodes of the cornplant have buds that have the capacity to develop intotillers or ears. These buds are stimulated to developtillers in favorable environments (i.e. adequatemoisture, good fertility, reduced plant populations,border rows, etc.) or after early season injury. Theunusually high number of corn plants with tillers thisyear is probably associated with the very favorableconditions for corn growth of these past few weeks.

• Hybrids vary in their propensity to develop tillers. However, it is not uncommon for a hybrid that has ahigh proportion of tillering this year to produce fewtillers next year. Environment tends to be moreimportant than hybrid when it comes to tillering in agiven year. If you are growing a hybrid that yieldswell, don’t abandon it just because it has tillers thisyear.

• Tillering generally does not have a detrimental effecton corn yield, nor it is beneficial to yield. Tillersrarely form ears so do not contribute directly to yield,but the photosynthates produced in the tillers canreadily move to the main stem if no ear forms on thetiller.

• Tillers very commonly produce tassel-ears, tasselsthat develop kernels and appear like an ear. Tassel-ears generally will not contribute to yieldsignificantly and can be problematic in environmentsthat are prone to the development of aflotoxins.

Joel RansomExtension Agronomist - Cereal Crops

[email protected]

Tiller in corn


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WHEAT STREAK MOSAIC VIRUS UPDATEReports of wheat streak mosaic virus (WSMV)

infection in spring wheat are fairly common in a fewlocations across the state now. In most cases, the sourceof the virus infection appears to be some volunteer winterwheat that was not destroyed far enough in advance (atleast two weeks) of planting spring wheat, either in thesame field or in the immediate vicinity. Incomplete burndown of volunteers can result in unexpected outbreaks ofwheat streak, because the “green bridge” for the mite andvirus has not been broken.

Warm, dry weather makes WSMV much worse,because the wheat curl mite that transmits the virusmultiples more rapidly. Under these conditions, the mitedoesn’t like stressed plants and seeks new, greener tissue.The virus makes damage worse if the plant is alreadystressed from heat and drought

Chemicals are not available to control the mite or thevirus. Cool, wet weather would favor the crop and not thedisease or mite - but continued, hot dry weather will makefor additional crop damage.

In most cases, it is too late to destroy the crop andplant something else. If growers chose to destroy a field,they should first consult with their insurers to see aboutlevels of compensation. They may be asked to leave acheck strip. Yield losses will depend on the extent ofinfection across a field and also on how early the crop wasinfected. Damage is greater when the plant is infectedyoung, but little yield loss occurs if infections occurs atflag leaf stage or later.

Destruction of infected volunteers will be a must thisfall, prior to any planting of winter wheat in these areas.Prior to planting is the time to control WSMV.

WHEAT DISEASE OBSERVATIONS, June 12-20NDSU IPM’s summer field scouts primarily found

tan spot in wheat fields across the state during the weekof June 12-16. Leaf rust was observed in Richlandcounty on June 19, at severity levels between 1 and 5%. Dry conditions in many areas has prevented severedevelopment of fungal leaf spots or leaf rust, althoughsome high risks of infection are still indicated on theNDSU small grain disease forecasting web site for thoseareas that have had rain.

On June 13, the NDSU Plant Pathology Departmenthosted a group of wheat pathologists from around the US,to talk about research results and research needs. On afield tour to spring wheat and winter wheat plots in CassCo., a small amount of stripe rust was found by Dr. TimMurray, wheat pathologist from Washington State Univ.

The group also found a fair amount of Septoria leafblotch in the winter wheat plots in Prosper. Dr. ShaukatAli, NDSU Plant Pathology Dept., confirmed that thespecies of Septoria was Septoria tritici, a species weusually find on wheat in the northeast part of the state.

Blake Vandervorst, of Ducks Unlimited, reportedsevere powdery mildew on winter wheat at plots nearEllendale. On June 20th, he reported that fungicidetreatments (early season followed by floweringapplication) reduced the powdery mildew significantly. Powdery mildew is rarely a problem in wheat in ourregion, but I have received several reports of itsoccurrence across the eastern half of ND and intoMinnesota this year. Most fungicides that are registeredfor wheat have good activity against powdery mildew, butearly detection is the key for successful control.

NDSU DISEASE FORECASTING SITEOn June 20, the NDSU forecasting site

(http://www.ag.ndsu.nodak.edu/cropdisease/)had some areas indicated to be of moderate risk forFusarium head blight on very susceptible or susceptiblespring wheat varieties. This area extended from Dickeyand LaMoure counties in the south, northward to theCanadian border. The risk was associated with recentrains and high relative humidity across those counties. Other areas of the state were at low risk for Fusariumhead blight (scab).

Dr. Shaukat Ali of the NDSU Plant Pathology Dept.has begun his Fusarium graminearum spore counts acrossseveral locations. For example, the June 14-16 airsamples from Carrington indicated high spore counts, butthe subsequent collections on June 17-19 resulted in lowspore counts. The environment at Carrington on June 14-16th also was favorable for FHB infection, because oflong dew periods. These same days also had weatherfavorable for leaf disease infections.

The spotty rain showers and subsequent variable risksof Fusarium head blight or leaf disease for individuallocations makes it harder to predict disease severity acrossa region this year. Good field scouting and attention todisease risk as indicated by the NDSU diseaseforecasting web site will be critical for good fungicidedecisions in 2006!

Marcia McMullenExtension Plant Pathologist

[email protected]


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KEEP AWARE OF SOYBEAN CYST NEMATODEAlthough the soybean cyst nematode (SCN) has only

been confirmed in Richland County, soybean growers inadjacent and other counties also need to be on the lookoutfor this pest. Fields infested with high populations of SCNin Richland County are already exhibiting signs andsymptoms of infection. The white to cream-colored SCNfemales are already visible on soybean roots in infestedfields (see figure) and yellowing and stunting is alreadyoccurring. With the high temperatures and low moistureoccurring this year in parts of Richland County, susceptiblevarieties planted in infested fields may suffer some bigyield losses. Crop rotation with a non-host (such as corn orwheat) and planting resistant varieties are the two majormethods of managing SCN. If you suspect SCN in yourfield, send soil samples from the affected area and themargins of the affected area to a laboratory (such as theNDSU Plant Diagnostic Lab) that can test for SCN.

SCLEROTINIA RISK MAP FOR CANOLAThe Sclerotinia Risk Map for canola has begun this

season. Maps will be posted twice per week at theNorthern Canola Growers Association website andthrough the NDAWN website at:

http://www.northerncanola.com/ andhttp://www.ag.ndsu.nodak.edu/aginfo/sclerotinia/sclerotinia.htm

The maps base their risk on the prediction of theemergence of apothecia in the soil, which are the“fruiting” structures of the Sclerotinia sclerotiorumfungus that produce the airborne spores that causeinfections. Canola is only at risk if it is flowering, as thespores must first infect a senescing flower petal to causedisease. Fungicides registered for control of Sclerotiniastem rot of canola include Topsin M, Ronilan, andEndura. These fungicides should be applied when thecanola plants are between the 30 to 50% flowering stages.

Carl A. BradleyExtension Plant Pathologist

[email protected]

GLYPHOSATE PRICE QUIZWith all of the different glyphosate formulations with

their different concentrations and prices on the market,how do you compare them? For example, take these threehypothetical glyphosate products.

Price per gallon Standard rateGlyphosate #1Glyphosate #2Glyphosate #3

$16$22$26

32 oz/a22 oz/a20 oz/a

Which glyphosate is the best buy (withoutconsidering the potential value of supporting services orguarantees)? Is it too confusing? There is an easy way tocompare products by calculating the cost per pound ofglyphosate. It’s easier than you think. Just follow thisformula.

$/gal lb glyphosate acid/gal = $/lb of glyphosate

The missing piece of information is the concentrationof the glyphosate in the jug. Check the ingredientstatement on the label for the concentration of theglyphosate acid or acid equivalent (the glyphosate acid isthe part that kills the weeds). Here are the label statementsfor these glyphosate products. The wording will differamong products, but look for the concentration ofglyphosate acid per gallon.

Glyphosate #1Contains 4 lbs per gallon glyphosate, isopropylamine saltAcid Equivalent: glyphosate acid = 30.4% (3 lb/gal)

Glyphosate #2Contains 5.5 pounds per U.S. gallon of the activeingredient glyphosate, in the form of its potassium salt.Equivalent to 4.5 pounds per U.S. gallon of the acid,glyphosate.

Glyphosate #3Contains 5 pounds per U.S. gallon of glyphosate acidequivalents.

Again, which glyphosate is the best buy? Just punchthe numbers through the formula to get the answer. In thishypothetical example, Glyphosate #2 is the best buy at$4.89/lb of glyphosate. Glyphosate #1 is $5.33/lbglyphosate and Glyphosate #3 is $5.20/lb glyphosate.

Disclaimer: These prices were randomly picked to showhow prices can be compared. They do not reflect any realproduct prices.

Tiny, oval shaped SCN females on a soybean root(courtesy Craig Grau, Univ. of Wisconsin)


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WHAT IS THIS WEED - WILD STRAWBERRYI am receiving many calls and people sending

pictures what they describe as wild strawberry. This plantis rough cinquefoil (Potentilla norvegica). Some peopleout west call it Norwegian cinquefoil (see common name).

Rough cinquefoil is in the Rose family, is an annual,winter annual, or biennial. Stems are 1 to 3 feet tall,rough, semierect and spreading. Leaves has three leafletslike strawberry, are hairy, and are coarsely toothed. It iscan be missed by glyphosate even at full use rates.

ND PETITIONS BEING SUBMITTED TO EPAThe following are registration petitions that the ND

Dept of Ag has funded to be put on the fast track in IR-4to get EPA registration as soon as possible. Thesepetitions may still take a few years before registrationoccur. This is an FYI only. Do not assume growers canuse these products because they are in the registrationprocess.

Pesticide common names are given instead of tradenames because they may be several trade names for eachcommon name. The active ingredients are herbicides,insecticides, and fungisicides.

Barley diflubenzuron, fenpropathrin,thiomethoxam

Bean (dry) flumioxazin (preharvest)Buckwheat sethoxydim (EPA decision - Mar 07)Canola thifensulfuronFlax deltamethrin, sulfentrazonePea (dry) fluazinam, glyphosateSafflower clethodim, glyphosate (PRE), paraquat,

thifensulfuron, zeta cypermethrinSunflower fenamidone, thiophanate, glyphosate,

tribenuron (Express resistant)Wheat diflubenzuron, flufenacet,

pendimethalin

CROP ROTATION RESTRICTIONSEach year I receive calls asking "Is it safe to plant

crop X if I sprayed herbicide Y last year?" or "Can Irecommend herbicide Y if a grower is planting crop Xnext year?" The answers to these questions are usuallyeasy, but sometimes not popular. The reason the answersare easy is because most herbicide labels are quite specificin listing the rotational crops or intervals allowed ANDthe label is a legal document. So, if the label states "Donot plant the following crops", it means that it is not legalto plant that crop.

The obvious reason that a rotational crop may not beallowed to be planted is because the herbicide maycarryover and injure the crop. Neither the grower nor themanufacturer wants this to happen. The manufacturerconducts field studies to determine the risk of carryover torotational crops in setting rotational intervals.The second reason some crops may not be allowed as afollow crop is not visible like injury. The EPA protectsour food supply by only allowing acceptable levels ofpesticide residues in food or feed. This residue level iscalled a "tolerance" and as long as the concentration ofthat pesticide is below the EPA-approved tolerance, it islegal. For example, sweet corn has a tolerance of 0.25ppm for atrazine. In a high percentage of sweet corn,atrazine is not even detected, but the tolerance allowing atrace amount of atrazine is the safe guard provided byEPA.

If herbicide residues persist in the soil and are takenup by a rotational crop, that crop may contain illegalresidues unless a tolerance exists or unless themanufacturer determined through field tests that noresidues are detected in the rotational crop. Certainrotational crops are not allowed because the manufacturerhas not conducted the field tests to determine that the cropis free of herbicides residues, even though the crop is notinjured. This the case with acetochlor. Currently, the onlycrops that can be planted after acetochlor is corn, wheat,soybean, and sorghum. Basic manufacturers haveconducted the necessary residue trials and EPA iscompleting the re-registration of acetochlor. The endresult is many rotational crops will be added to the newlabel when issued.

Whether the crop rotation is not allowed because ofthe risk of crop injury or potential herbicide residues, orlack of registration, the answer to the question is the same.Read and follow the label. "Do not" or "Shall not" meansdo not. In some causes, the labels offer the userrecommendations or advice such as "Injury may occur ifsoybeans are planted the following year." In this case, it isthe grower’s choice if they want to accept the risk ofinjury, but they are warned. On labels, "should" is anotherword that is advisory.

Basically, if we want to have these tools available forour use and maintain the confidence of the public, weneed to follow the label instructions.


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On another note, there is evidence of application ofunregistered products on crops. For example, the 2004ND Pesticide Use Survey shows Assure II applied on 85,000 acres of sunflower, dry bean, and flax. Assure II isnot labeled on these crops. Residue studies have beencompleted but EPA has not yet set a tolerance orregistered these crops.

This may happen in a year or two but this use is not yetapproved. Other good alternative products, like Poast andclethodim (Select, others) are available so there should beno reason why Assure II should be applied until it isregistered on these crops.

Richard ZollingerNDSU Extension Weed Specialist

[email protected]

YELLOWHEADED SPRUCE SAWFLY UPDATE The Yellowheaded spruce sawfly is a damaging defoliating insect of spruce plantings in North Dakota. The insect is

found throughout the northern half of the state and is most damaging in the northern tier counties and counties of the northcentral region. Infrequently the insect is found in the southern half of the state however severe damage is rarely observed(Figure 1).

Figure 1. Yellowheaded spruce sawfly risk map for ND


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Generally, small and medium sized spruces growingin full sunlight appear to be more susceptible to theyellowheaded spruce sawfly because female sawfliesprefer to lay eggs on spruce growing in open areas.Damage to the tree is caused by the feeding larvae (figure2) that may consume needles for up to 4 weeks. Larvaestop feeding in mid to late summer, drop to the groundand spin cocoons.The damage to spruce trees caused by the sawfly can be

substantial. Repeated defoliation causes reduced growthand at times tree mortality. Needles consumed by thesawfly are not re-grown.

Generally spruce trees require 5 to 7 years of needleretention for optimal growth and survival. Needle lossfrom sawfly defoliation reduces the trees ability to convertsunlight into energy. This stress may exacerbate other pestproblems or if severe enough, can kill the tree outright.

On June 13th, the first signs of defoliation wereobserved on the currents year’s shoots of spruce in thenorth half of the state. The larvae will continue to feed forseveral weeks thereby causing additional damage. Controlmeasures must be incorporated within the followingweeks to minimize sawfly damage. Handpicking larvaemay be sufficient to reduce damage on small isolatedtrees. Additionally, a strong jet of water will oftendislodge feeding larvae.

Chemical controls may need to be incorporated ifmany trees are infested and the potential for damage ishigh. Insecticides can effectively reduce populations ifapplied properly. Unfortunately, most people do notnotice sawfly damage until mid to late summer whendefoliation has already occurred, the larvae are absent,and insecticides are ineffective. Insecticides are mosteffective if used to target early larval stages such as thosethat are feeding at this time of year. Early larval stagesshow high survival, whereas older larvae experiencesubstantial mortality. Acephate and carbaryl are labeledfor use to control sawflies for homeowners. Always readand follow label instructions!

Michael KangasForest Health Specialist

North Dakota Forest Service

Figure 2. Yellowheaded spruce sawfly larvae


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Below is a summary of samples diagnosed in the past week (research samples and seed health testing results are notincluded):

Host Diagnosis Taxonomic name CountyAlfalfa Herbicide Injury; Exposure Abiotic pathology WalshApple Black Rot Botryosphaeria obtusa CassAsparagus Animal Damage Abiotic pathology BeckerBarley Drought Stress Damage Abiotic pathology RichlandBarley High Temperature Damage Abiotic pathology RichlandBlack Ash Cottony Ash Psyllid Psyllopsis discrepans ClayBur Oak Oak Anthracnose Gnomonia quercina CassCanola Environmental Stress; Problem Abiotic pathology WalshChokecherry Peach Leaf Curl Taphrina deformans StarkCorn Environmental Stress; Problem Abiotic pathology RichlandCorn Herbicide Injury; Exposure Abiotic pathology UnknownCotoneaster Oystershell Scale Lepidosaphes ulmi ClayCrabapple Mechanical Damage Abiotic pathology CassGrape Grape Black Rot; Foliage Dis. Guignardia bidwellii!ph'ctina BeckerGrass (pasture) Spittle Bug Aphrodes sp. BowmanHoneylocust Cottony Maple Scale Pulvinaria innumerabilis CassHorseraddish Red Turnip Beetle Entomoscelis americana ClearwaterJuniper Abiotic cause; undetermined Abiotic pathology RichlandMaple Iron Deficiency Abiotic pathology CassMaple Maple Anthracnose Gloeosporium apocryptum DickeyMaple Phyllosticta Leaf Spot Phyllosticta sp. Grand ForksPine Diplodia Tip Blight Sphaeropsis sapinea CassPine Salt Damage Abiotic pathology BowmanSiberian pea shrub Insect Damage Abiotic pathology CassSoybean Growth Regulator Effect Abiotic pathology CassSpring Wheat Wheat Streak Mosaic Virus Virus; rhymovirus: Potyviridae Bottineau, Emmons, McIntosh, SargentSpruce Abiotic cause; undetermined Abiotic pathology WellsSpruce Chemical injury Abiotic pathology McintoshSpruce Environmental Stress; Problem Abiotic pathology BowmanSpruce Growth Regulator Effect Abiotic pathology Golden ValleySpruce Salt Damage Abiotic pathology BowmanSugarbeet Aphanomyces damping off Aphanomyces cochlioides CassSugarbeet Beet Water Rot; Seedling Dis. Aphanomyces cochlioides ClaySugarbeet Fusarium Fusarium oxysporum probable CassSugarbeet Fusarium Blight Fusarium sp. CassSugarbeet Fusarium Root Rot Fusarium sp. CassSugarbeet Herbicide Injury; Exposure Abiotic pathology CassSugarbeet Pythium Root Rot Pythium sp. CassSugarbeet Rhizoctonia Damping Off Rhizoctonia sp. CassSunflower Cultural/Environmental Problem Abiotic pathology EmmonsSunflower Environmental Stress; Problem Abiotic pathology CassSunflower Herbicide Drift Or Carryover Abiotic pathology CassSunflower Wireworm Elateridae PolkTomato Growth Regulator Effect Abiotic pathology Cass

Kasia Kinzer; NDSU Plant Diagnostic Labhttp://www.ag.ndsu.nodak.edu/diaglabe-mail: [email protected]

Telephone: 701-231-7854206 Waldron Hall, PO Box 5012Fargo, North Dakota 58105


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South-Central ND

During the past week (June 14-20), rainfall recorded atNDAWN sites located in the region ranged from 0(Harvey) to 1.25 (Carrington) inches. Additional rainfallis needed across the region, especially west of Hwy 3.Based on NDAWN estimates, the region’s average dailywater use on June 20 ranged from 0.15 to 0.35 inches forwheat, corn, soybean and sunflower. Hail occurred inportions of Logan and McIntosh counties last week.

April-planted spring wheat will be in the flowering stagethis week. Farmers are struggling with the decision ofapplying fungicide at wheat anthesis for leaf diseasecontrol and scab suppression due to generally dryconditions. At a winter wheat trial near Ellendale,significant amounts of leaf rust and powdery mildew arepresent in susceptible varieties. Early-planted field pea isflowering and flax should soon be in bloom. Row cropsare actively growing and generally are in good condition,except in western counties. Most corn is in the 5- to 6-leafstage and soybean in the second- to third-trifoliate stages.Insect levels continue to be very low (e.g. aphids andthrips in small grain). Soybean aphid have recently beenfound in the state so fields should be checked for thisinsect as well as the bean leaf beetle.

Greg EndresArea Extension Specialist/Cropping Systems

NDSU Carrington Research Extension [email protected]

North Dakota State UniversityCROP & PEST REPORTExtension EntomologyHultz Hall 202Fargo, ND 58105-5346

Janet Knodel, editorEntomology231-7582 phone231-8557 fax

Plant Pathology231-8866 phone231-7851 fax

Plant Sciences231-7972 phone231-8474 fax

Soils231-8881 phone231-7861 fax

Weeds231-7972 phone231-8474 fax

Ag Engineering231-7261 phone231-1008 fax

Helping You Put Knowledge To WorkThe information given herein is for educational purposes only. References to a commercial product or trade name is made with theunderstanding that no discrimination is intended and no endorsement by the North Dakota Extension Service is implied.

NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and the U.S. Department of Agriculturecooperating. Duane Hauck, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914.We offer our programs and facilities to all persons regardless of race, color, national origin, sex, handicap, age, Vietnam era veteransstatus, or sexual orientation; and are an equal opportunity employer.This publication will be made available in alternative formats for people with disabilities upon request (701) 231-7881.

NDSU Crop and Pest Report http://www.ag.ndsu.nodak.edu/aginfo/entomology/ndsucpr/index.htm

No. 8 June 22, 2006 - North Dakota State University · Winged aphids were present. ... necessarily...

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Transcript of No. 8 June 22, 2006 - North Dakota State University · Winged aphids were present. ... necessarily...