insect pests of potatoes in home gardens

2017 Virginia Tech 3104-1553 (ENTO-256NP)

InsectPestsofPotatoesinHomeGardensEricDayandThomasKuhar,DepartmentofEntomology,VirginiaTech

ColoradoPotatoBeetleDescription Adults are orange with stripes on theabdomen and spots on thorax and are about 3/8-inch-longby1/4-inchwide.Larvaeare1/2-inch-long,orange-pinkincolor,andhavespotsontheirsides.

ColoradoPotatoBeetlelarvabyEricDay

PlantsAttacked:Itisamajorpestofpotatoes,eggplant,and tomatoes and subsists on various weeds such ashorsenettleandbuffaloburr.

Damage: Both larvae and adults strip away the foliageoften leaving only the midribs and stems. Heavilydamagedplantshaveloweryields.Life cycle:The CPB overwinters in the soil as an adult.Afteremerginginlatespring,theyfindandstartfeedingonpotatoplants. Shortly after that, they lay eggs.Afteregghatchthelarvaefeedingroupsontheundersidesofleaves.Organic Control: insecticides containingBacillusthuringiensisSanDiego,neem(azadirachtin),spinosad,orcryoliteareeffectiveifapplicationsaretimedtocoincidewithpeakegghatchandsmall-larvaeactivity.CulturalControl:Rotatingpotatoestoadifferentpartofthe garden and using heavymulch at planting timewillreducethenumbersofbeetlesthatfindtheplants.Handpickingwillhelp,butistimeconsuming.Beetleshouldbedroppedintosoapywater.ChemicalControl:Foliarspraysofspinosad,abamectin,and the materials listed under organic control. Oldermaterials such as the organophosphates phosmet,phorate, and methamidophos; the organochlorineendosulfan; and numerous pyrethroids (esfenvalerate,permethrin, bifenthrin, cyfluthrin, lambda-cyhalothrin,etc.)maystillprovideeffectivecontrol inregionswhereresistance is not a major problem.

PotatoLeafhopperDescription: Several species. Adults: Green wedgeshaped, up to 1/8 inch long; they fly quickly whendisturbed.Nymphsresembleadultsbutaresmaller;theycrawlsidewiselikecrabs.Common Host Plant(s): Beans, lettuce, alfalfa, andpotato.Also,candamageshadetreessuchasmaple.

Leafhopper(USDA)

Damage:Adultsandnymphsattackbeansandpotatoes.Leavesofbeanscurl,orrolldownward,crinkle,andtendto become yellow or bronze. Some plants are dwarfedandmaydie.Potatoesattackedbyleafhoppersdevelopacondition called hopperburn. Tips and sides of potatoleaves curl upward, turn yellow to brown, and becomebrittle.Distribution:ThroughoutVirginia.CulturalControl:Pickanddestroyinfestedleaves.Organic/Biological Control: Lacewings, damsel bugs,ladybeetles,minutepiratebugs,andspidersareincludedamongthenaturalenemiesofleafhoppers.Dustingplantslightly with diatomaceous earth may help controlleafhoppers.Chemical Control: Treat with a registered insecticidewhendamagefirstappears.

2017 Virginia Tech 3104-1553 (ENTO-256NP)

PotatoTuberworm

Description:Pinkishwhite,brownhead,up to1/2-inchlong.

Larvaofthepotatotuberworm,Phthorimaeaoperculella(Zeller).PhotographbyOregonStateUniversityExtension.

CommonHostPlant(s) Potato.Also foundoneggplant,tomatoesandpepper.Damage: Tunnels in stems, leaves, and tubers. Shootswiltanddie.Distribution:ThroughoutVirginiaLifecycle:Larvaeorpupaeoverwinterintubersorinthesoil.Mothsappearinspringandmaybeseenatdawnorduskwhen they are normally active orwhenplants aredisturbed.Femaleslay60-200eggs,singly,onplantsinaslittleasfourdays.Usuallyeggsaredepositedinthetubereyesorontheundersideofpotatofoliage.Larvaeemergein3-6days.Larvaeoftenenterpotatotubersthroughtheeyes, leavingfrassaroundtheeye.Larvaemayfeednear

thetubersurfaceortunneldeeplyintothetuber,leavingatrailofexcrementalongtheirpath.Duringthesummerlarvae mature in 7-10 days and pupate in soil or plantdebris around potato plants. Second generation mothsemerge in approximately a week. Multiple generationsoccurannuallyinVirginia.CulturalControl:Protectivemeasuresforcontrollingthepotatotuberwormincludethefollowing:1) plantonlyseedpiecesthatarenotinfested,2) cultivate so as to hill the soil against the plants -keeping at least 2 inches of soil over the developingtubers,3) harvestassoonasthecropismature.Duringharvest,donot leavethedugpotatoes inthe fieldovernight,anddonotcoverpilesofpotatoeswithpotatotops,4) destroy all culled or infected potatoes as soon aspossible,5) store tubers at temperatures below 52 degrees F ispossible and practical. Use either new or thoroughlycleaned bags or basketswhen storing. The storage areashouldbescreenedorenclosedinsuchawaythatmothcannot get in. Without such an enclosed storage area,moths can still fly in and still become a problem eventhough the storage area was clean and potatoes insect-freewhenstored.Organic/Biological Control: Natural enemies of thepotato tuberworm include two braconid wasps (Orgiluslepidus Muesebeck and Bracon gelechiae Ashmead),whichparasitizethelarvae.Chemical Control: There is no known chemical controlforthisinsectinstoredpotatoes.