published by utah state university extension and …...chinch bugs damage turfgrass leaves with...
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Published by Utah State University Extension and Utah Plant Pest Diagnostic Laboratory September 2013ENT-169-13PR
Chinch BugsKelly Kopp, Extension Water Conservation and Turfgrass Specialist, Ryan S. Davis, Arthropod Diagnostician,
and Ricardo A. Ramirez, Extension Entomologist
DO YOU KNOW
• ChinchbugsareoccasionalpestsofturfgrassinUtah.
• ChinchbugsfeedonavarietyofturfgrassspeciesincludingKentuckybluegrass,perennialryegrass,thefescues,bentgrassandzoysiagrass.
• Damageisusuallyheaviestinsunnylocationsduringhot,dryperiods.
• Soundcultural(non-chemical)practicesarethebestdefenseagainstchinchbugdamage.
Figure1.Adultchinchbug.
INTRODUCTIONChinchbugs(Fig.1)are“truebugs”.InUtah,thecommonchinchbug[Blissusleucopterusleucopterus(Say)],andwesternchinchbug(Blissus occiduus)mayfeedonturfgrass,especiallyunderconditionsofsevereheatanddrought.Coupledwithunder-irrigation,directsunlight,andthickthatch,chinchbugnumberscansoarfrommid-summertoearlyfall.
Adultsoverwinterinthatch,clumpsofgrass,nexttobuildingsandalongtheedgesofsidewalks.Theyemergeinearlyspringtomate(whentemperaturesreach70ºF).Femalesinserteggsonundergroundroots,behindleafsheathsinthecrownsofturfplants,inthefoldsofgrassblades,orinthethatch.Eggshatchinmidtolatespringwithdevelopmentofimmaturestagesrequiringapproximately1month.Adultsofthefirstsummergenerationbegintoappearinearlytomidsummer.Eggsofthesecondsummergenerationhatchapproximately1monthlaterandcompletedevelopmentinearlytomidfall.Adultsof
BIOLOGY thisgenerationmovetooverwinteringsitesastemperaturescoolinthefall.
IDENTIFICATIONChinchbugsgothroughnumerousdevelopmentalstages(Fig.2).Firststagenymphsofthecommonchinchbugaretiny(1/64in)andbrightredwithawhitebandacrosstheabdomen(Fig.2).Astheymaturethroughfivenymphalstages,theyturnorange-brownandthenblack.Adultsareblack(1/10inlong)andwhitewithfullydevelopedwingsthatfoldoverthebackandextendtotheendoftheabdomen(Figs.1&2).Thiscreatesablacktrianglepatternbehindthepronotum
Actualadultlength
Chinchbugsdamageturfgrassleaveswithpiercing-suckingmouthparts,inhibitingtransportofwaterwithintheplant.Patchydiebackisfollowedbylargerareasofdamage.Inseverecases,completelawnlossmayoccur(Fig.5).Chinchbugfeedingdamagecanoftenresembledroughtstress;damageisoftenworseonplantsthatarealreadyaffectedbydrought.Chinchbugdamagewillnotrespondtoincreasedwateringasadrought-affectedlawnwould.
DAMAGE
Actualadultlength
Figure2.Immature(nymph)andadultchinchbugs.
(“shoulders”),pointingtowardtherear.Somepopulationsofadultchinchbughavereduced-sizedwingsasadults.Whencrushed,chinchbugsemitafoulodorlikestinkbugs(Vittumetal.,1999).
Thereareseverallook-alikeinsectsthatcanalsobefoundinturf.Bothbig-eyedbugs(Fig.3)andminutepiratebugs(Fig.4)arebeneficialpredatorsandshouldbepreserved.FalsechinchbugsalsoappearsimilartochinchbugsbutrarelyoccurinturfgrassinUtah.
andimidacloprid.Withcurativeproducts,likebifenthrin,thegoaloftheiruseistocoverturfgrassstemsandtheupperthatchsothatthechinchbugsarecontrolledbydirectcontact.Lightirrigationmayalsohelptomoveliquidinsecticidesdownintothethatchlayerwherechinchbugsreside.Ifthethatchandsoilareverydry,irrigatingonthedaypriortoinsecticideapplicationmaybewarranted.Ifgranularproductsareused,thefoliageshouldbedrysothattheprillsdon’tsticktotheleavesandreachtheupperthatch.Lightirrigationfollowinggranularinsecticideapplicationisalsorecommended(Potter,1998).
Preventivetreatment,usingsystemicproductslikeimidacloprid,forchinchbug
Figures3&4.Chinchbuglook-alikes.Big-eyedbug(top);minutepiratebug(bottom).Bothinsectsarebeneficialpredators.
Hands-and-Knees Method
Thesimplestmethodfordetectingandmonitoringchinchbugsisthe“handsandknees”method.Usingyourthumbsandfingers,pullbackgrassstemstoexposethecrownsandthatchwherechinchbugadultsandnymphsmaybehiding.Thenymphsareverytiny,however,andmaybeeasilyoverlooked(Fig.6).Asconditionsbecomewarmanddrier,chinchbugsmaymovedeeperinthethatch.Becausetheyaresosmall,ahandlensormagnifyingglassmaybeneededtoseethem.Visualobservationofdrivewaysandsidewalksadjacenttodamagedturfareasonhotafternoonsoftenrevealsadultchinchbugsrunningacrossthepavement.Adultchinchbugsmayalsobeobservedcrawlingonthesidesoflight-coloredbuildingsundertheseconditions.Chinchbugsshouldnotbeconfusedwithsimilarlooking,beneficialinsectslikeminutepiratebugsandbig-eyedbugs(Figs.3&4).
MONITORING
Figure5.Severechinchbugdamagemayleadtocompletelossofturfgrass.
Figure6.Chinchbugnymphsareverysmallandeasilyoverlooked.
Chinchbugsandtheirdamagegenerallyoccurinscatteredpatchesinturfgrass.Populationsmayreach200to300bugspersquarefeetinheavilyinfested,sunnyareas.DamageistypicallyvisiblefromlateJunethroughAugustwhentheoldersummergenerationnymphsandadultsarefeeding(NiemczykandShetlar,2000).DamagemaybeseenearlierinsouthernUtah.
“Floatation” Trap
A“floatation,”traptomonitorchinchbugscanbemadefroma6-inchdiametercoffeecanorsimilarobjectwithbothendsremovedtocreateametalcylinder.Pushthecanintothesoilapproximately2to3inchesdeep,enclosingtheturfandfillthecanabout¾fullofwater.Pokeorstirtheturfandthatchthatisunderwaterkeepingaconstantdepthofwaterinthecanforabout10minutesbypouringinextrawatertoreplacethelost/leachingwater.Countthenumberofchinchbugsthatfloattothesurface.
CONTROL
Cultural Control
Emphasizinghealthyturfisrecommendedtodiscouragechinchbuginfestations.Usethefollowingculturalcontrolmethodstominimizechinchbugdamage:
• Aerateonceortwiceperyeartoreducethatch,especiallyinlawnspronetothatchdevelopment.
• Ifchinchbugdamageisnotsevere,adequateirrigationandlightfertilizationapplicationscanencourageturfgrassrecoveryandtolerance(Potter,1998).
• EncouragemoistsoiltofosterthegrowthofBeauveriafungus,anaturalbioticpathogenofchinchbug.Conversely,applicationoffungicides
UtahStateUniversityiscommittedtoprovidinganenvironmentfreefromharassmentandotherformsofillegaldiscriminationbasedonrace,color,religion,sex,nationalorigin,age(40andolder),dis-ability,andveteran’sstatus.USU’spolicyalsoprohibitsdiscriminationonthebasisofsexualorientationinemploymentandacademicrelatedpracticesanddecisions.UtahStateUniversityemployeesandstudentscannot,becauseofrace,color,religion,sex,nationalorigin,age,disability,orveteran’sstatus,refusetohire;discharge;promote;demote;terminate;discriminateincompensation;ordiscriminateregardingterms,privileges,orconditionsofemployment,againstanypersonotherwisequalified.Employeesandstudentsalsocannotdiscriminateintheclassroom,residencehalls,orinon/offcampus,USU-sponsoredeventsandactivities.ThispublicationisissuedinfurtheranceofCooperativeExtensionwork,actsofMay8andJune30,1914,incooperationwiththeU.S.Dept.ofAg.,NoelleE.Cockett,VicePresidentforExtensionandAgriculture,UtahStateUniversity.
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Precautionary Statement:UtahStateUniversityExtensionanditsemployeesarenotresponsiblefortheuse,misuse,ordamagecausedbyapplicationormisapplicationofproductsorinformationmentionedinthisdocument.Allpesticidesarelabeledwithingredients,instructions,andrisks,andnotallareregisteredforediblecrops.“Registereduse”pesticidesmayonlybeappliedbyalicensedapplicator.Thepesticideapplicatorislegallyresponsibleforproperuse.USUmakesnoendorsementoftheproductslistedherein.
Figure 1.ImagecourtesyofGrahamMontgomery,CornellUniversity. Figure 2.ImagecourtesyofSamuelAbbott,UtahStateUniversity.Figures 3&4.ImagescourtesyofBradleyHigbee,ParamountFarming,Bugwood.org.Figure 5.ImagecourtesyofKatieWagner,UtahStateUniversityCooperativeExtension,SaltLakeCounty.Figure 6. ImagecourtesyofNatalieHummel,LouisianaStateUniversityAgCenter.
-Davis,R.Fall2012.Turfageddon:Thechinchbuginvasion.UtahPestsNews.Vol.VI.http://utahpests.usu.edu/htm/utah-pests-news/up-fall-2012-newsletter/chinch-bug-invasion/(accessedNov.2012).-Niemczyk,H.D.,andD.J.Shetlar.2000.Destructiveturfgrassinsects(2ndEd.).H.D.N.Books,Wooster,OH.-Potter,D.A.1998.Destructiveturfgrassinsects:biology,diagnosis,andcontrol.AnnArborPress,Chelsea,MI.-Vittum,P.J.,M.G.Villani,andH.Tashiro.1999.TurfgrassinsectsoftheUnitedStatesandCanada(2ndEd.).CornellUniversityPress,Cornell,NY.-Sheltar,D.J.,andAndon,J.2011.ChinchBugsinTurfgrass.EntomologyFactSheet,HYG-2503-11.TheOhioStateUniversity.
FactSheetSeries:Insects—Turf
IMAGES & REFERENCES
maysuppressBeauveriaandfavorthebuildupofchinchbugpopulations.
• Fertilizeregularlytoimpartsomeresistanceofturfgrasstochinchbugdamage.
• Plantoroverseedturfwithendophyte-enhancedcultivarsofperennialryegrass,fine-leaffescueortallfescuewhichareresistanttochinchbugsandcommonturfdiseases.
• Kentuckybluegrasslawnswithahighpercentageofnon-endophyticfine-leaffescueand/orperennialryegrass,andlawnswithexcessivethatch,areespeciallysusceptibletochinchbugdamage(Potter,1998).
Chemical Control
AnumberofinsecticidesarelabeledforcontrolofchinchbuginUtah.Forhomeowners,thereareseveralactiveingredientssuchasbifenthrin,lambda-cyhalothrin,cyfluthrinandimidaclopridthatareavailable.Forcommercialapplicators,inadditiontoactiveingredientsavailableforhomeowners,clothianidin(Arena;non-restricteduse)andseveralrestricted-useproductsthattypicallycontainacombinationofpyrethroidsandneonicotinoidsarealsoavailable(Aloft,Allectus).
Withcurativeproducts,typicallypyrethroids(e.g.,bifenthrin),thegoalistocoverturfgrassstemsandtheupperthatchlayersothatthechinchbugsarecontrolledbydirectcontact.Preventivetreatment,usingsystemicproductslike
neonicotinoids(e.g.,imidacloprid)thatmoveintotheplant,isgenerallynotwarrantedaschinchbugsrarelycausesufficientdamageinUtah.Ifchinchbugsarepositivelyidentifiedasthecauseofseveredamage,thenspot-treatmentofinfestedareasisabetteroptiontocontroltheirpopulation.
Turfinsecticidesmaycomeinliquidorgranularform.Withliquidformulations,irrigationshouldbeavoidedforseveraldaysafterapplicationtoallowtheinsecticidetocontactthebladesofgrassandthatchwherechinchbugsreside.Somelabelsmay,however,recommendlightirrigationtomoveliquidinsecticidesdownintothethatchlayer.Ifthethatchandsoilareverydry,irrigatingonthedaypriortoinsecticideapplicationmaybewarranted.Whenusinggranularformulations,thefoliageshouldbedrysothattheprillsdonotsticktotheleavesandreachstemsandtheupperthatchlayer.Lightirrigationfollowinggranularinsecticideapplicationisrecommended(Potter,1998).
Treatment Thresholds
Infestationsof20to25nymphspersquarefootaregenerallyconsidereddamagingenoughtowarrantcontrol.Usingthe“floatation”techniquementionedabove,estimatethenumberofnymphsfoundpersquarefootbasedontheareacoveredbythecan.Ifnymphnumbersarebelowthisthreshold,regularirrigationandfertilizationcanmitigatechinchbugdamage.