Weed Control and Issues in Developing CountriesPeter R Hobbs609 BradfieldDepartment Crops and Soil Science

Challenge for AgricultureTo increase food production sustainably to meet food security needs of a growing population now and in the future while at the same time minimizing the effects on the environment and improving the livelihoods of those involved in agricultureImprove the efficiency of natural resource use needed for agriculture

Convergence of opinionsDemand for food - increasingHarvested area - possibly shrinkingTraditional sources of productivity growth are they exhausted?More competition for blue waterMore severe weather as a result of GHG emissions and global climate changeIn addition, there is resource and environmental degradation?

Resource Poor Farmers?Subsistence Farmers?Not produce enough food to feed their family or market any excess. Nutritional quality of food produced can also be poor.Lack basic infra-structure to transport, store and sell the food they growLack income and access to credit to invest in new technologyLittle capacity to manage risks associated with technology

NepalBangladeshPakistanIndiaSouth AsiaIGP

Indo-Gangetic PlainsThe population of South Asia is over 1.5 billion and increased at 1.8% per year over last 6 years. 27.3 million more mouths to feed each year!! 75K/day; 3,116/hr(IRAQ = 23 million; NY + Mass = 25m; More than 400 million are poor (< $1/day)The per capita rice-wheat growing areas have shrunk from 1200 m2 in 1961 to less than 700 m2 in 2000. Demand for rice and wheat will grow at 2.5% per year in the next 20 years. This has to come from yield growth.

Source: Indian Census Report

Population Dynamics

Population density in RW area of Indo-Gangetic PlainsSource: Dave Hodson, GIS Lab, CIMMYTRW zoneMid-hills NorthTransition SouthRW area population = 280 millionRW area pop density = 517 /sq kmGreen area population = 430 millionGreen area pop density = 452 /sq km

Rice-wheat systems in South AsiaRice and wheat grown in the same calendar year in S. Asia (13.5 m has)Rice in the wet monsoon summer and wheat in the dry cool winterRice grown by puddling soil and transplanting seedlingsThis creates a problem for the next wheat crop because of poor soil physical properties This also affects soil biology

R-W Systems CalendarJFMAMJJASONDJFMAMonthRiceWheatWheatRice-1Rice-2WheatWheatThere are also rotations of RW with SugarcaneRiceNRNR = potato, vegetable, legume, oilseedWheatWheatWheatGMRiceWheatSummerWinter

Phalaris minor issueThis WAS a major problem in NW India and Pakistan in wheat in the 1990s.Herbicide resistant Phalaris to Isoproturon started show in early 1990sIt became a major problem by mid-1990sNeed for integrated weed management approaches rotations, tillage, seed, variety etc.

Promote Integrated Weed Management SystemsHand weedingRotations use of a fodder cropInter-cultivationMulching allelopathic properties of some residues and cover cropsPrevent seed set of weedsClean seedUse herbicides when needed in proper mannerEtc.

Crisis in Haryana (and Punjab, UP)Herbicide tolerant Phalaris minor seen as early as 1992-93 wheat season Crisis level reached by 1995-96 In affected fields, Phalaris populations up to 3000 plants/ m3 wheat crop squeezed out Problem spreading fast into neighboring states

Photo: LW Harrington

Phalaris minor (little seeded canarygrass)

A desperate search for solutionsImproved management - crop rotations, timely sowing, clean seed, etc. of limited helpNew herbicidesZero tillage (?)Major role played by R.K. Malik, Haryana Agricultural UniversityPhoto: LW Harrington

Grain yield of wheat and population of Phalaris under zero and conventional tillage.Source: RK Malik and scientists at Haryana Agricultural University

Chart1

1376163952405030

370.4595.654905342

192.839456885482

30.899.457235636

16.428353705230

ZTPOP

CTPOP

ZTYIELD

CTYIELD

Year

Phalaris population (no/m2)

Grain Yield (kq/ha)

Sheet1

80040001608801040137610004400390110513001639

30084072400240370.45051050305608510595.6

110625182056192.8240835270315310394

223210187230.8114381381258299.4

0.1271743416.42889178788083

600041005600540051005240590037005450530048005030

600052005500525055005490610051005360480053505342

600052655500480068755688587052005200474064005482

672057005600584547505723668057005500580045005636

630045005200485060005370625045005100480055005230

YearZTPOPCTPOPZTYIELDCTYIELD

1997-981376163952405030

1998-99370.4595.654905342

1999-2K192.839456885482

2000-0130.899.457235636

2001-0216.428353705230

Sheet1

0000

0000

0000

0000

0000

ZTPOP

CTPOP

ZTYIELD

CTYIELD

Year

Phalaris population (no/m2)

Grain Yield (kq/ha)

Sheet2

Sheet3

Chart1

1376163952405030

370.4595.654905342

192.839456885482

30.899.457235636

16.428353705230

ZTPOP

CTPOP

ZTYIELD

CTYIELD

Year

Phalaris population (no/m2)

Grain Yield (kq/ha)

Sheet1

80040001608801040137610004400390110513001639

30084072400240370.45051050305608510595.6

110625182056192.8240835270315310394

223210187230.8114381381258299.4

0.1271743416.42889178788083

600041005600540051005240590037005450530048005030

600052005500525055005490610051005360480053505342

600052655500480068755688587052005200474064005482

672057005600584547505723668057005500580045005636

630045005200485060005370625045005100480055005230

YearZTPOPCTPOPZTYIELDCTYIELD

1997-981376163952405030

1998-99370.4595.654905342

1999-2K192.839456885482

2000-0130.899.457235636

2001-0216.428353705230

Sheet1

0000

0000

0000

0000

0000

ZTPOP

CTPOP

ZTYIELD

CTYIELD

Year

Phalaris population (no/m2)

Grain Yield (kq/ha)

Sheet2

Sheet3

Another pleasant surpriseIt took the Phalaris crisis for farmers to try no-tillResult of farmer trials huge enthusiasm for cost reductionIncreasing number of projects, farmer trialsTraveling seminars helped promote awareness in1998Private sector kept improving implements

Photo: LW Harrington

Means and ends keep changing!No till originally seen as a means of advancing sowing dates Breakthrough with farmers came with no-till as a means of helping control Phalaris minor

Essential local manufacturers were involved and linked to farmers Continued farmer interest in no-till as a means of reducing costs

Photo: LW Harrington

New HerbicidesTopik -- ClodinafopPuma -- FenoxypropLeader Sulfosulfuron -- SulfonylureaGrasp -- Tralkoxydim

Need to be applied with a sprayer low quantities active ingredient used per hectare used (10-50 grams/ha)

No-Tillage with Inverted-TBased on inverted-T coulter from NZGood where no loose residues including anchored strawLocally made and low costCan adapt present farmer machineryUses 15-25% less waterLess weeds germinateService providers means small farmers can use

No-TillConventional

Phalaris population over time

Herbicide Application Using Knapsack Sprayers essentialA. Miller and R. Bellinder, Cornell University, in cooperation with Dr. R.K. Malik (HAU), Dr. L.S. Brar (PAU) G. Singh (GBPUAT Pantnagar) J. Ranjit (NARC) and Dr. P. Hobbs (CIMMYT)

Resource poor farmer systems for herbicide application

Los Banos, Philippines. Puddling rice soils with carabao

Rice planting methods

Weeding in Rice

TaiwanGirls weeding rice

No-till rice-wheatIn order to get the full benefit of no-till wheat, also need to no-till riceProblems of weeds because difficult to pond water when no puddlingTraditionally hand weeded Tedious and usually done by womenOne solution would be to introduce herbicide resistant rice varietiesUse of cover crops

Other Future Issues RiceBetter 0-till and DSR varietiesOryza sativa by O. glaberimma crossesChromosome substitution linesUse of Genetic EngineeringRoundup ready riceBlast resistant riceDrought tolerant riceImproved equipment for seeding rice

Herbicide Tolerant (HT) RiceWeed Control: Mechanical, HerbicidesHerbicides: Broad Spectrum ie. Glyphosate, GlufosinateNarrow Spectrum ie. 2,4 - D

LD50 = 4320 mg/kgDDT = 115Parathion = 30Bt = >5000

Gene Source:various bacteriaHow does it work:Insert gene for herbicide de-toxificationReplace herbicide target with gene that is resistant to herbicide

Herbicide Tolerant (HT) Crops

Benefit of HT to Environment?Depends on Herbicide not GM PlantPost emergence broad spectrum Roundup herbicide replace numerous narrow spectrum herbicides that are more toxicDepends on breakdown product of herbicide in plant/soilAllows farmer to practice no-till and conservation agriculture practices

Negative issuesWeeds used for fodderEmployment of the poor for weedingAvailability of technology to resource poor farmers:Credit to buy sprayer and herbicideTraining in proper useSpurious products on the marketExtension of improved system poor

Maize in Zambia -- Traditional

Zambia Basin System

Conservation AgricultureResidue retention distinguishes Conservation Agriculture from conventional farming systems, which are characterized by leaving the soil bare and unprotected, exposed to climatic agents.The soil cover is not incorporated into the soil by tillage.(FAO, 2002)

***************************Taiwan Girls weeding rice*******