chickpEa disEasE managEmEnT FACT SHEET - Grains Research ...

may 2013chickpea disease managementFACT SHEETSouthern RegionManaging Fungal Diseases of ChickpeaSAn integrated approach to managing fungal diseases in chickpeas in the southern region should focusprimarily on ascochyta blight while also paying attention to botrytis grey mould and sclerotinia.Key PointsChoose an ascochyta blightresistant variety.Ensure the paddock is more than500 metres from chickpea stubble.Aim for a break of at least fouryears between chickpea crops.Use seed from a clean paddockfor sowing.Use a fungicide seed dressing,especially in high disease risksituations.Do not sow too early, even with anascochyta blight resistant variety.Management of fungal diseases inchickpeas in the southern grains regionshould focus primarily on ascochytablight. The disease can attack the plantat any growth stage and its preventionshould be the priority in any chickpeadisease management program.Photo: Gordon CummingAscochyta blight (AB)Ascochyta blight (Phoma rabiei, previouslyknown as Ascochyta rabiei) can attack theplant at any growth stage. Its preventionshould be the priority in any chickpeadisease management program.The first symptoms are small, pale, watersoakedspots (lesions) on younger leaves.In wet conditions these lesions enlarge andjoin with others to blight leaves and buds.Small black bodies called pycnidia (Figure1) are visible within the lesions.Stem lesions can result in stem deathabove the lesion and breakages. Infectedplants can partially recover by reshootingbelow stem lesions.Aim for 35 to 50 plants per squaremetre, depending on the situationand crop type (kabuli or desi).Monitor crops regularly duringthe growing season for diseasedevelopment and take appropriateaction to reduce disease impact.Observe good on-farm hygieneto reduce disease sources andprevent spread.Varieties resistant to ascochytablight still require foliar fungicide atpodding.Harvest early to minimise infectionof seed. Crop desiccation enableseven earlier harvest.Integrated diseasemanagementA single disease management strategyrarely provides complete disease control.Using a number of integrated diseasemanagement (IDM) techniques, is morelikely to control diseases.IDM aims to:1. reduce background inoculum levelsthrough paddock selection, control ofvolunteers and stubble management;2. exclude pathogens through the use ofclean seed and farm hygiene; and3. protect the crop by using resistantvarieties, seed treatments andstrategically applied foliar fungicides.Management of fungal diseases inchickpeas in the southern grains regionshould focus primarily on ascochyta blight,paying attention also to botrytis grey mouldand sclerotinia.Chickpeas can also be damaged byseedling root diseases, root lesionnematodes and viruses so an integratedapproach is essential.Round, sunken lesions with pale centresand dark margins can form on pods laterin the season (See Figure 2). AB canpenetrate the pod wall and infect the seed.Severe pod infection can result in reducedseed set and discoloured seed.Losses are worse in wet springs in cropswith dense canopies.Reduce old chickpea residue and aimfor a break of at least four years betweenchickpea crops.AB resistance in a chickpea varietydoes not mean immunity, but will delaydisease onset and reduce the need forfungicide applications.Under high disease pressure, even resistantvarieties can suffer production losses orgrain quality damage.Botrytis grey mould (BGM)Botrytis grey mould (Botrytis cinerea) canattack the plant at any growth stage.Level 1, Tourism House | 40 Blackall Street, Barton ACT 2600 | PO Box 5367, Kingston ACT 2604 | T +61 2 6166 4500 | F +61 2 6166 4599 | E grdc@grdc.com.au | W www.gdrc.com.au

Figure 1. The concentric circles ofbrown-black dots in the centre of the leaflesions are known as pycnidia. Thesefruiting bodies are unique to ascochytablight and are useful in identifying thedisease. Leaf death may also be causedby frost or herbicide injury but in thosecases, there will be no pycnidia present.It can be seed-borne, attacking theseedling during emergence and causingrot on the upper taproot and collar.Affected areas develop a soft rot anda fluffy grey mould (See Figure 3).Significant losses can occur in wet springsin crops with dense canopies.Use seed from disease-free crops for sowing;apply a seed dressing and foliar fungicides.Fungicides such as chlorothalonil ormancozeb for ascochyta blight can givesome protection against BGM, dependingon the timing of application.However applying a product, such ascarbendazim, that specifically targets BGMduring flowering to protect flowers andsubsequent pods will be more effective.SclerotiniaSclerotinia (S. sclerotiorum and S. minor) cancause significant crop losses in chickpeas ineastern Australia, but it is sporadic.Photo: Gordon CummingFigure 2. Round, sunken lesions indicatingascochyta blight infection on chickpeapods later in the season. The funguspenetrates the pod wall and infects theseed, resulting in reduced seed set anddiscoloured seed.The disease is readily identified as whitemycelial growth on infected plant tissue,which later produces small, black survivalbodies called sclerotia (See Figures 4 and 5).It is favoured by cool, wet conditions inwinter and spring, and may first appear ifthere are very wet conditions in July.Control by using disease-free seed and byrotating with cereals and other non-host crops.Fungal disease managementOn-farm hygieneAB and BGM carry over from one seasonto the next on infected stubble, seed oron volunteers. Control volunteers preseedingto limit build-up of diseaseinoculum for the new crop.It is a good idea to reduce stubble(chop, bury, destroy, graze or burn infectedcrop residue) where it will not create anerosion risk.Photo: DPI VictoriaPaddock selectionDo not sow adjacent to old chickpea stubble,particularly downwind, and aim to separateby a distance of at least 500 metres.A break of at least four years betweenchickpea crops will minimise soil inoculum.Herbicide residues may increasesusceptibility to disease. Observe themaximum plant-back period for:sulfonylurea;imidazolinone;pyridine;phenoxy;benzoic;quinoline; andtriazine.Note that plant-back periods for someherbicides have a rainfall requirement. Forexample, for OnDuty ® (Group B), the plantbackperiod requires 150 to 200 millimetresof rain over 10 months. For 2,4-D Ester(Group I), the plant-back period (dependingon rate applied) is 14 days following at least15mm of rain in a single event.Paddocks with low soil fertility or nutrientstatus can lead to stress, predisposingchickpeas to disease.VarietiesYield and marketability, along with diseaseresistance, are the major factors toconsider in variety choice (See Table 1).Seed for sowingUse seed of the highest possible purity,germination and disease-free status.Photo: kevin moorePhoto: kevin moorePhoto: DPI VictoriaFigure 3. Botrytis cinerea producesdiffuse, whitish fungal growth which thenturns grey due to the production of hugenumbers of spores born in clusters atthe ends of dark stalks. Free moisture isnecessary for germination and infectionof botrytis grey mould.Figure 4. Sclerotinia is identified as whitemycelial growth on infected plant tissue,which later produces small, black survivalbodies called sclerotia. When thesesclerotia germinate in the soil they releaseairborne spores that infect above-groundparts of the chickpea plant, often startingin leaf axils.page 2Figure 5. Fungal weft of sclerotinia inthe lower canopy of a chickpea crop.The disease produces a white mycelialgrowth, like cottonwool, that covers theinfected tissue.

AB epidemics can be initiated by verylow levels of seed infection. If growinga susceptible variety, use seed with nildisease infection. Infected seed may notemerge, but can spread disease whentransported elsewhere.BGM can be carried on seed andsignificantly affect crop establishment if nottreated with a fungicide seed dressing.Seed retained on-farm for sowing shouldbe from a disease-free paddock. Selectthe area early, apply fungicides at podding,and harvest before any other chickpeas toprevent contamination.If seed is more than one year old, frosted,weather damaged or diseased, thengermination and vigour may have deteriorated.This may increase its susceptibility to diseaseattack. Re-test to determine germinationpercentage before sowing.Seed dressingNo variety is resistant to seed infection byAB or BGM.Kabuli types and all ascochyta blightsusceptible varieties should be treated witha fungicide seed dressing.All AB resistant varieties – desi or kabuli –will benefit from a seed dressing to protectagainst BGM and other seedling rots.Note that varieties with AB resistance aresusceptible in pods and seeds, and thefungus can survive between crops on theseseeds. A seed dressing is an advantage tocontrol transfer of AB ascochyta blight onseed in resistant varieties, as well as thosethat are susceptible.Seed dressings may harm rhizobia,particularly under acid soil conditions.Minimise the contact time between themand check the inoculum label.Apply the seed dressing first, thenseparately mix the inoculum and apply itto the seed immediately before sowing.Alternatively consider using granular orliquid injection inoculums.Sowing dateSow within the optimum times for thevariety and region and sow AB resistantvarieties on traditional sowing dates.For susceptible varieties, delayed sowing isan important strategy for AB management,reducing the time that seedlings areexposed to disease favourable conditions.However, delayed sowings can result in loweryields due to increased risk of dry finishes andhigh temperatures during podding.For all varieties, sowing too early can leadto poor early pod set or seed fill if floweringin a colder period (less than 15°C meandaily temperature).In a disease-prone area or higher-risksituation, sow at the later end of therecommended optimum for the district.Sowing rateAim for 35 to 50 plants per square metre,depending on the situation and crop type(kabuli or desi).Higher seeding rates (and early sowing)lead to greater canopy vigour, increasedlodging and higher humidity, and underideal growing conditions can increase therisk of BGM.Seeding at rates below the minimumrecommended plant population has minimalimpact on fungal disease incidence, butreduces potential yield and increasesharvest losses.Row spacingWider row spacing does not reduce ABincidence in chickpeas, but could reducethe occurrence of BGM. It may also allowbetter fungicide penetration and coverage.Disease monitoring and controlperiodsA fully integrated disease managementpage 3program should be initiated before sowingand maintained through the growingseason to greatly reduce disease impact.Potentially critical periods for diseasedevelopment in chickpeas are the earlyvegetative stages (for AB susceptiblevarieties), flowering and during seed fill.The decision to spray or not will depend onvariety resistance and the disease risk forthe individual crop.Disease monitoring should start at sixto eight weeks after emergence if thecrop is susceptible, as regular fungicideapplications are necessary in thesevarieties.Fungicide applicationConsider the variety grown, potential cropyields, rainfall zone and disease risk whendeciding on a fungicide program.Apply a seed dressing, particularly forkabuli varieties, to protect against seedlingroot rots and to provide early protectionagainst AB.Treat seed in high ascochyta blight risksituations, irrespective of the variety.For both AB and BGM, a seed treatmentcontaining thiram (Thiragranz ® , Thiraflo ®ST, Thiraflo ® FF or Thiram) or thiram plusthiabendazole (P-Pickel T ® , Fairgro ® ,or Reaper ® TT) will reduce seed-borneinfection.Table 1 Disease resistance rating A of current chickpea varieties.VarietyAscochyta blightFoliage/stemPodBotrytis grey mouldKabuliAlmaz A MS B S SGenesis Kalkee MS B S SGenesis 079 R S MSGenesis 090 R S SGenesis 114 MS B S SGenesis 425 R S SKaniva S S SDesiAmbar A R C S -Genesis 509 R S MSFlipper A MR-MS B S SGenesis 510 R S SGenesis 836 MS S SNeelam A R C S -Howzat A S B S MSJimbour S S MSPBA Boundary A MR B S SPBA HatTrick A MR B S SPBA Slasher A R S SPBA Striker A MR S SYorker A MS S SA National ratings as supplied by Pulse Breeding Australia (PBA) 2012: R – resistant, MR – moderatelyresistant, MS – moderately susceptible, S – susceptible,B Note ascochyta blight ratings revised for these varieties 2012; C Provisional rating supplied by COGGO.AVarieties displaying this symbol beside them are protected under the Plant Breeders’ Rights Act 1994.

A fungicide program needs to account forthe following:Disease risk categories. Base onvarietal susceptibility or resistance;source and treatment of seed; plantingproximity to previous season’s chickpeastubble; level of AB inoculum presentfrom crop residue or volunteers;and climatic conditions in relation topotential disease infection.Registration status. The productmust be registered or have a permit forthe disease and use.Withholding period. All products andtimings used in the fungicide programmust meet Australian withholdingperiods and export slaughter intervals.Fungicide resistance management.Adhere to the maximum number ofsprays of a product to minimise the riskof fungicide resistance developing.Mode of action. Rotate betweenmodes of action to reduce the risk offungicide resistance developing andimprove efficacy. Fungicides are alsorecommended at times of the diseaselife cycle where they will be most effectiveaccording to their mode of action.Cost effectiveness. Fungicide usemust be cost effective.Fungicide treatments for ABChlorothalonil is the more effective foliarfungicide for AB. Only Unite ® 720 and Barrack ®720 are registered for this use on chickpeas.Mancozeb and metiram can also providesome protection from AB if timelinessof application is observed; for example,mancozeb might protect for a fortnightwhile chlorothalonil could protect for 21days under certain conditions.Efficacy differences between products canarise if AB is present. Protective fungicidesprays should be applied one to three daysahead of rainfall to prevent the infectionspreading. No new ascochyta blightinfection will occur during dry periods, sofungicide application can be held off untilrain (more than five millimetres) is forecast.Do not wait until after the rain.With ascochyta blight resistant varieties likePBA Slasher A , Genesis 090 or Genesis079, spraying for ascochyta blight beforeproduced by www.coretext.com.authe podding stage is unnecessary,especially if no lesions are present.A single application of chlorothalonil atpodding, ahead of a rain event, may besufficient for grain protection in moreresistant cultivars. A repeat application maybe necessary only in severe and extendeddisease pressure situations.Varieties with intermediate resistance– that is moderately susceptible (MS)to moderately resistant (MR) – suchas Genesis Kalkee, Genesis 114,Genesis 836 or Almaz A will requirethree to four foliar fungicide applicationsduring vegetative stages, as well as duringpodding to protect yield and seed quality.Susceptible (S) varieties such as Howzat Aor Kaniva need between four and 10fungicide sprays throughout the growingseason (timing is critical) with spraysapplied ahead of rain fronts.Fungicide treatments for BGMBGM in seedlings can reduce plantestablishment throughout the growingseason if infected seed is sown.Warm, humid conditions under a densecrop canopy in spring are ideal for thespread of BGM.Carbendazim is the most effectivefungicide against a BGM epidemic. Use ofchlorothalonil, mancozeb or metiram as afoliar spray for control of ascochyta blighthas the added benefit of providing someprotection and reduction of BGM.Applications targeted at AB during poddingmight however be too late for BGM.Early harvestHarvest at maturity to minimise ascochytablight seed infection and potentialdowngrading. Seed damage from ABis usually more severe when crops areharvested late.Chickpea crop desiccation assists in earlyharvest, but care is needed because of thelate maturity. Do not crop-top or desiccateprematurely as it can affect grain quality,particularly kernel or seed coat colour.Early harvest will also give the best chanceof achieving number 1 grade chickpeareceival standard.Further informationJenny DavidsonSouth Australian Research andDevelopment Institute08 8303 9389jenny.davidson@sa.gov.auWayne HawthornePulse Australia0429 647 455wayne@pulseaus.com.auKurt LindbeckNSW Department of Primary Industries02 6938 1608kurt.lindbeck@dpi.nsw.gov.auHelen RichardsonVictorian Department of PrimaryIndustries03 5362 2111helen.richardson@dpi.vic.gov.auUseful resourcesPulse Breeders Australiawww.grdc.com.au/pbaChickpea: Disease managementstrategy – southern regionwww.pulseaus.com.auChickpea: Botrytis grey mouldmanagementwww.pulseaus.com.auChickpea: Integrated diseasemanagementwww.pulseaus.com.auChickpea checklist for southerngrowerswww.pulseaus.com.auAscochyta blight of chickpeawww.dpi.vic.gov.au (search AG1186)Sclerotinia of chickpeawww.dpi.vic.gov.au (search AG0453)Chickpea Disorders: the Ute Guidewww.grdc.com.au/GRDC-UteGuide-ChickpeaDisordersDisclaimerAny recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of the Grains Research and Development Corporation.No person should act on the basis of the contents of this publication without first obtaining specific, independent, professional advice.The Corporation and contributors to this Fact Sheet may identify products by proprietary or trade names to help readers identify particular types of products.We do not endorse or recommend the products of any manufacturer referred to. Other products may perform as well as or better than those specifically referred to.The GRDC will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using or relying on the information in this publication.CAUTION: RESEARCH ON UNREGISTERED PESTICIDE USEAny research with unregistered pesticides or of unregistered products reported in this document does not constitute a recommendation for that particular use by the authors or the authors’ organisations.All pesticide applications must accord with the currently registered label for that particular pesticide, crop, pest and region.Copyright © All material published in this Fact Sheet is copyright protected and may not be reproduced in any form without written permission from the GRDC.page 4GRDC Project codesDAN00151, DAN00147, PAL00017Acknowledgements: Jenny Davidson,Wayne Hawthorne, Kurt Lindbeck,Helen Richardson.