e-21-w vegetable insects - urban agroecology
TRANSCRIPT
MANAGING INSECTS IN THE HOME VEGETABLE GARDEN
Rick E. Foster and John Obermeyer, Extension Entomologists
Department of Entomology
Vegetable InsectsE-21-W
PURDUE EXTENSION
Insectsfeedingonhome-grownvegetablesareafactoflifeformostgardeners.Gardeners’twochoicesaretotoleratethedamageorattempt toprevent it.Frequently, toleratingthedamageisareasonableapproach.Forexample,whentomatoesbegintoripen,mostgardenershavemoretomatoesthantheycanpossiblyuse.So,caterpillarschewingonafewfruitsarenorealconcern.Cornearwormsusuallyconfinetheirdamagetothetipsofsweetcornears.Aviablestrategyistocutoffthedamagedtipsbeforecookingthecorn. Anotherapproachistoplantcropslesssusceptibletoinjuryfrominsectfeeding.Table1categorizesvegetablecropsasneverorrarely,sometimes,andusuallyoralwaysdamagedbyinsects. Thereareanumberofpracticesthatthehomegardenercanemploytoreduceinsectproblems.
• Properlydisposeofplantresiduesfromthepreviousyear’sgarden.
• Plantvarietiesthatarerecommendedforuseinyourarea,andplantthematthepropertimeforbestgrowth.Plantingtooearlywhenthesoiliscoolmaymaketheplantsmoresusceptibletosomesoilinsects.
• Inspecttransplantsbeforepurchasetomakesuretheyarehealthyandnotinfestedwithinsects.
• Useproperplantspacings,fertilizers,water,andculturalpracticestoinsurevigorousplantgrowth.Plantsthataregrowingvigorouslyoftencantoleratemoreinsectdamagethanpoorlygrowingplants.
• Keepthegardenasweed-freeaspossible.Thiswillhelpthe plants to continue to grow vigorously, and weedsmayharborinsectsthatalsowillattackthevegetables.However, thepresenceofweedsorcompanionplantsmayincreasethenaturalenemypopulation.
• Inspectplantsregularlyforinsectsorinsectdamage.Earlydetectionmeansmoreeffectivecontrolandcanreducethe amount of damage suffered. Particularly in smallgardens,early-detectedcaterpillars,loopers,hornworms,andlargebeetlescanoftenbehandpickedfromplantsanddestroyedbeforetheycauseproblems.
• Treatmost vegetableswith insecticidesonlywhenpestinsectsareobserved;however,treatcertainvegetables,such as cantaloupes, cucumbers, and squash, on apreventivebasistoavoidseriousdamage.
INSECTICIDES Several types of insecticides are available for homegardeners.Table2 lists the insectsmost commonly foundonvegetablesandtheinsecticidesrecommendedtocontrolthem.Thefollowingsectionsdescribe thevarious typesofavailableinsecticides.
Botanical Insecticides (extracted from plants) Neem:Theactive ingredient inNeem,azadirachtin, isderivedfromleavesorseedsofneemtrees.Ithasactivityagainstavarietyofinsectpests.Formanypests,neemactsasarepellent,ratherthanatoxicant.Therefore,itisimportanttoapplyneembeforeaseriousinfestationispresent. Pyrethrum is derived from the flowers of certainchrysanthemums. It causes rapid paralysis and apparent
TABLE 1. Frequency of Insect Damage to Various Vegetables Grown in the Home Garden
Never or Rarely Sometimes Usually or Always
Carrot Asparagus Broccoli
Greenonion Bean Cabbage
Lettuce Pepper Cantaloupe
Pea Spinach Cauliflower
Radish Tomato Cucumber
Eggplant
Potato
Squash
Sweetcorn
2Managing Insects in the Home Vegetable Garden — E-21-W
death, but insects may subsequently recover. Pyrethrumprovidescontrolforupto1dayandismosteffectiveagainstsoft-bodiedinsectssuchasscalesandaphids.
Microbial Insecticides Microbial insecticides available to the home gardenercontainsporesof thebacteriumBacillus thuringiensis (Bt),whichparalyzestheinsect’sgutafterbeingeaten.ABtstraineffectiveagainstmanycaterpillarsissoldasDipel,Javelin,MVP,etc.StrainssoldasM-TrakorNovodorareeffectiveagainsttheColoradopotatobeetle.Microbialinsecticidesarenottoxictobeneficialinsects,humans,orothervertebrates.Spinosadisarelativelynewfermentationproductthathasgoodactivityagainstmostcaterpillars,Coloradopotatobeetles,andthrips.
Manufactured Insecticides Carbaryl (Sevin)isawidelyusedinsecticidewithseveraltradenames.Itiseffectiveonbeetlesandsomecaterpillarsbutdoesnotkillaphids.Carbarylispersistentonplantsfor3-4days,butmaycauseoutbreaksofaphidsandspidermitesbykillingnaturalenemies. Malathion ismoderately effective on a wide range ofinsects,especiallysuckinginsects.Itispersistentonplantsfor2-3days. Several pyrethroid insecticides (bifenthrin, cyfluthrin, esfenvalerate, lambda cyhalothrin, and permethrin) areavailable ffor homeowners to use on vegetables. Theseproductsaresoldunderavarietyoftradenames,sobesuretochecktheactiveingredientonthelabel.Thecropsincluded
TABLE 2. General Garden Pests Commonly Found on Vegetables and Recommended Insecticides to Control Them.
Pests Vegetables Attacked Recommended Insecticides*
Aphids Manyvegetables 2,4,9,11,13,14
Asparagusbeetle Asparagus 3,9,15
Beanleafbeetle Bean 2,3,8
Blisterbeetle Manyvegetables 2,3,8,11
Cabbagelooper Cabbage,cauliflower,broccoli 1,2,5,8,12,15
Coloradopotatobeetle Potato,tomato,eggplant,pepper 1,2,5,8,12,15
Cornearworm/fruitworm Corn,tomato,bean 1,2,3,4,5,8,12,15
Cucumberbeetle Bean,cucumber,melon,squash,pumpkin 2,3,8
Cutworm Manyvegetables 2,3bait,5,8,12
Europeancornborer Corn,pepper,bean 1,2,3,4,5,8,12,15
Fleabeetle Manyvegetables 2,3,4,5,8,12
Grasshopper Manyvegetables 2,3,5,8,11
Importedcabbageworm Cabbage,cauliflower,broccoli 1,2,5,8,12,15
Japanesebeetle Manyvegetables 2,3,5,8,11,12
Leafhopper Bean,potato 2,3,5,8,11,12
Mexicanbeanbeetle Bean 2,3,4,5,8
Slugs Manyvegetables 6,10
Squashbug Cucumber,melon,squash,pumpkin 2,3,5,12
Squashvineborer Squash,pumpkin 2,3,5,12
Tarnishedplantbug Manyvegetables 2,3,4,5,8,9,12,13
Tomatohornworm Tomato,potato,eggplant,pepper 1,2,3,4,5,8,12,15
Twospottedspidermite Manyvegetables 2,7,9
Whitefly Manyvegetables 2,5,9,11,13
*1.Bacillus thuringiensis(Dipel,Javelin,M-Trak,etc.)9.Malathion2.Bifenthrin10.Metaldehyde3.Carbaryl11.Neem4.Cyfluthrin12.Permethrin5.Esfenvalerate13.Pyrethrins6.Ironphosphate14.Soap(insecticidal)7.Kelthane15.Spinosad8.Lambdacyhalothrin
3 Managing Insects in the Home Vegetable Garden — E-21-W
onthelabelvary,sobesurethatthecropyouaretreatingislistedbeforeyouspray.Allofthepyrethroidsareextremelyeffective insecticides that will provide up to 7-10 days ofcontrolofawidevarietyofpests.TheywilleffectivelycontrolColoradopotatobeetlesthatareresistanttoinsecticidessuchasSevin.Pyrethroidsareextremelytoxictofish,socautionshouldbeusedaroundbodiesofwater.Pyrethroidsarealsotoxictohoneybees.Inorganic Insecticides (oils and soaps) Horticulturaloilsworkonlyoncontactandhavenoresidualactivity.Commerciallyavailableinsecticidalsoaps,whicharemadefromnaturallyoccurringfattyacids,helpcontrolaphids,leafhoppers,mites,scales,andwhiteflies.Likeoils,soapsonlycontrolthoseorganismsonwhichthespraylands.
Some Notes About Insecticides• Althoughmostinsecticidesavailableforuseinthehomegardenarerelativelysafetouse,theyareallPOISONS andshouldbeusedwiththeutmostcare.Carefully read and follow all precautions on the insecticide label.Table3liststhenumberofdaysyoumustwaitaftertreatmentbeforeharvesting thevegetables.Vegetablesshouldbethoroughlywashedbeforetheyareeatenorcooked.
• Sometimes using an insecticide will increase insectproblems.Forexample,overuseofcarbarylonsomecropscanincreaseproblemswithaphids,mites,andwhitefliesbecauseitkillsthenaturalenemiesthateatthosepests,butdoesnotkillthepeststhemselves.
TABLE 3. Harvest Restrictions in DAYS for Common Vegetable Insecticides
Vegetable
Days After Treatment to Wait Until Harvest
Bac
illu
s
thu
rin
gie
nsi
s
Bif
enth
rin
Car
bar
yl
Cyfl
uth
rin
Esf
enva
lrat
e
Lam
bd
a C
yhal
oth
rin
Mal
ath
ion
Nee
m
Per
met
hri
n
Pyr
eth
rin
s
Sp
ino
sad
So
ap
Asparagus 0 NO 1 NO NO NO 1 0 1 0 60 0
Bean 0 3 3 7 A B 1 0 NO 0 3 0
Beet 0 NO 7 0 NO NO 7 0 NO 0 NO 0
Broccoli 0 7 3 0 3 1 3 0 1 0 1 0
Cabbage 0 7 3 0 3 1 7 0 1 0 1 0
Cantaloupe 0 NO 3 0 3 NO 1 0 0 0 3 0
Carrot 0 NO 7 0 7 NO 7 0 1 0 NO 0
Cauliflower 0 7 3 0 3 1 7 0 1 0 1 0
Cucumber 0 3 3 0 3 NO 1 0 0 0 1 0
Eggplant 0 7 3 7 7 5 3 0 3 0 1 0
Greenonion 0 NO NO NO NO 14 3 0 1 0 NO 0
Leaflettuce 0 7 14 0 NO 1 14 0 1 0 1 0
Peas 0 14 3 NO A B 3 0 NO 0 3 0
Pepper 0 7 3 7 7 5 3 0 3 0 1 0
Potato 0 21 7 0 7 NO NO 0 14 0 7 0
Radish 0 NO 7 0 7 NO 7 0 NO 0 NO 0
Spinach 0 NO 14 0 NO NO 7 0 1 0 1 0
Squash 0 3 3 0 3 NO 1 0 0 0 3 0
Sweetcorn 0 1 2 0 1 1 5 0 1 0 1 0
Tomato 0 1 3 0 1 5 1 0 0 0 1 0
NO-NotlegalforuseonthiscropA-3daysforfresh,21daysfordriedB-7daysforfresh,21daysfordried
4Managing Insects in the Home Vegetable Garden — E-21-W
• When properly applied, sprays and dusts should giveadequatecontrolofinsects.Plantsneedonlyalightcoatingofdust,butitmustbeonboththeupperandlowerleafsurfaces.Becauseofthis,shaker-candustersusuallydonotdoanadequatejob.Squeezeorplungerdustersprobablyarebetter,asareaerosoldusters if keptagitatedwhiledusting.Dustswillusuallybemoreexpensiveperounceofactiveingredientthansprayformulations.
•Whenspraying,bothupperandlowerleafsurfacesmustbetreated.Sprayerpressuremustbesufficienttorollleavesover.Aerosol cans of insecticide are not recommendedexcepttotreatindividualplantsorverysmallgardens.Unlessotherwisenotedonthemateriallabel,agallonofspraywillcoverapproximately500squarefeetor200feetofrow.
•Whenusedproperly,theinsecticidesavailableforusebyhomegardenerswillnot leavesufficientresiduesontheproducetocauseanyadversehealtheffects.Asanaddedprecaution,gardenersshouldrinseanyproducewithcleanwaterbeforeconsumingit.Thiswillalsohelpwashawaydirtandotherdebris.DO NOTwashvegetablesinsoapywater.Soapcanbedifficulttoremoveandhasnotbeentestedforsafetywhenconsumed.
ORGANIC GARDENING Although properly used insecticides do not adverselyaffecthumanhealth,somegardenersnonethelesschoosetogrowtheirvegetablesorganically.“Organic”meansthatnochemicalfertilizersorsyntheticpesticidescanbeused.Theuseofcertainpesticides,suchasBacillus thuringiensis,oilsandsoaps,pyrethrum,spinosad,andneemisallowed.Forthemostpart,vegetablescanbegrownforhomeconsumptionwithouttheuseofthechemicalinsecticides.Thismay,however,requiremoreworkthanifinsecticideswereused.
GENERAL GARDEN PESTS
White Grubs Severalspeciesofwhitegrubs feedon rootsorotherundergroundpartsofmost vegetables.Damagegenerallyconsists of root pruning, surface scars, or round gouges.Grubsaremostlyaproblem ingardens thatweresod thepreviousyear.Gardenswithgrassyweedsareattractivetobeetleswhentheylayeggs.Assoilispreparedforplantinginthespring,itshouldbecheckedforthepresenceofgrubs.
Christine
Brian
Whitegrubs
Wireworms Wirewormscan feedon seedsandseedlingsof corn,beans,andpeas,causingwiltingand/ordeathoftheyoungplant.Wirewormsfeedontheedibleportionsofpotato,sweetpotato, radish, carrot, rutabaga, and turnips. The roots ofcabbage,cucumber, tomato,onion,watermelon,andothercropsarealsoattacked,reducingvigororkillingtheplants.Despitethelonglistofhostplants,wirewormsarerarelyaproblemingardens.Wirewormsaremore likely to infestagardenifitweresodlastyearorhadlotsofgrassyweedspresent.
Obermeyer
J.
WirewormCutworms Cutwormsfeedonmostofthevegetablesgrowninthehomegarden.Themostcommondamageisyoungplantscutoffatthesoilsurface.Somecutwormsmayalsoclimbtheplantandfeedonfoliageandfruit.Damagecanbereducedbykeepinggardensfreeofweedsbeforeandaftervegetablesareplanted.Baitformulationsofsomeinsecticidescanalsoprovidecontrol.
University
Purdue
Obermeyer
J.
Variegatedcutworm Blackcutworm
Japanese Beetle InsomepartsofIndiana,theJapanesebeetleisthemostseriousinsectproblemthatmanyhomeownershavetocontendwith. Japanese beetles can be present in extremely highnumbers,arevoraciousfeedersonawidevarietyofplants,
Christine
Brian
Japanesebeetle
5 Managing Insects in the Home Vegetable Garden — E-21-W
andareverymobile,allowingthemtoconstantlyreinvadeatreatedyardorgarden.AlthoughJapanesebeetletrapscatchalargenumberofbeetles,theyarenotrecommendedforusebecausetheytendtoattractmorebeetlesthantheycatch.Unfortunately, theonlyway tosuccessfullyprotectgardenplantsthatarebeingattackedbyJapanesebeetlesiswithinsecticides.Neemcanbeaneffectiverepellent ifmultipleapplicationsarebegunwhenbeetlesfirstappear.
Tarnished Plant Bug Tarnishedplantbugsfeedwiththeirsuckingmouthpartsonbeet,chard,celery,beans,potato,cabbage,cauliflower,turnip, salsify, and cucumber. They suck plant juices andmay inject toxicsaliva into theplant.Leavesmaybecomedeformed,stemsandpetiolesmaybescarredanddiscolored,orthebudsanddevelopingfruitmaybedwarfedandpitted.Tarnishedplantbugsbecomeactiveearlyintheseasonandcanmigratetofindpreferredhostplants.
J.Obermeyer
J.Obermeyer
Tarnishedplantbugadultandnymph
Blister Beetles Adultblisterbeetlesfeedravenouslyontheleavesofmanyvegetables.Thebeetlescanbepickedoffofplantsbyhand,buttheycontainanoilthatcanblistertheskinifaccidentallycrushed.Thelarvaeofblisterbeetlesarebeneficial,burrowingthroughthesoilandfeedingongrasshoppereggs.
BrianChristine
Marginedblisterbeetle
Aphids Aphidsaresoft-bodiedinsectsthatfeedwiththeirsuckingmouthpartsontheleavesofmanygardenvegetables.Theyaremostcommonlyfoundinlargegroupsorcoloniesontheundersideofleaves.Aphidfeedingreducesthevigoroftheplantandmaycausetheleavestocurldownward.Aphidsaremostoftenkeptundercontrolbymanyofthenaturalenemies
thatfeedonthem.Theuseofinsecticidessuchascarbaryl(Sevin) tocontrolother insectswillsometimesresult inanoutbreakofaphids,becausethenaturalenemiesarekilledbytheinsecticide.
Univ.W
isconsin
C.W
elty
Greenpeachaphid Turnipaphids
Twospotted Spider Mite Althoughmitesarenotinsects,beingmorecloselyrelatedtospiders,theyarevegetablepeststhatremoveplantjuicesfromtheleavesofbeans,corn,tomato,eggplant,etc.Theleavesbecomebronzedoryellowed,andthefoliagetakesonageneralwiltedappearance.Thesymptomsofmitedamagemaybecausedbyotherfactors,sobesuretolookformiteswithahandlenstoconfirmyourdiagnosis.Mitesaremoreofaprobleminhot,dryweather.Heavyrainsmayhelptocontrolmites.Sprayingplantswithagardenhosecanremovesomeofthemitesfromtheplants.
J.Obermeyer
W.C
ranshaw
Twospottedspidermiteanddamageoneggplant
Slugs Slugsarenotinsects,buttheyarepestsofvegetablesthatmayskeletonizeorshredleavesofmanygardenvegetablesormaydefoliatetheentireplant.Slugsaremoreofaproblemincool,wetweather.Severaldaysofwarmsunnyweatherusuallywill reduce theproblem.Piepansbaitedwithbeerburiedatgroundlevelwilltrapmanyslugs.Chemicalcontrolsarealsoavailable.
BrianChristine
Slugoncorn
6Managing Insects in the Home Vegetable Garden — E-21-W
MANAGING INSECTS ON SPECIFIC CROPS
Asparagus The asparagus beetle and the spotted asparagus beetlearebothfoundonasparagus,butonlytheasparagusbeetleisaseriouspest.Adultasparagusbeetlesare1/4inchlong,blue-black,withcreamyyellowspotswithredborderson thewings.Adultspottedasparagusbeetlesareslightlylarger,arereddish-orange,andhaveblackantennae,eyes,andundersides.Eachwingcoverhassixdistinctblackspots.Thesoft-bodiedlarvaeoftheasparagusbeetlereach3/8inchlongandaregraywithblackheads.Adultasparagusbeetlesattackthetenderbudsnearasparagustipsassoonastheshootspushabovethesoilinthespring.Theadultsalsofeedonthefoliage.Larvaeoftheasparagusbeetlefeedonthestemsandleaves,butthelarvaeofthespottedasparagusbeetlefeedonlyontheberries. Destroyingcropresiduefromthepreviousyeareliminatesoverwinteringsitesfortheadults.Hand-pickingadultscanalsobeuseful.Chemicalcontrolisusuallyquiteeffectiveandmaybejustifiedifthereareseveralbeetlesorlarvaepercrown,orifplantsarelosingtheirleaves.
MichiganStateUniv.
MichiganStateUniv.
Asparagusbeetleadultandlarva
MichiganStateUniv.
Spottedasparagusbeetle
Beans Green,wax,broad,andlimabeansgrowninthevegetablegardenareallattackedbyseveralinsects,butthedamageoftencanbetolerated.Thefirstinsectthatwillattackbeansistheseedcorn maggot.Theadultformisaflythatisslightlysmaller thanahouse fly.Thedamaging form is the larva,whichisawhite,leglessmaggotthatburrowsintoseedsandseedlings,causingpoorseedgerminationandemergence,and/or stemswithout leaves.Damage can be reduced byplantingseedsshallowandwhensoiltemperaturesarewarm
(760°F),sothattheplantswillnotstayintheseedstagelong.Usinginsecticidetreatedseedsoroverseedingwillalsohelp.Earlyplantinganduseofmanureforfertilizerwill increaseproblems.
J.Obermeyer
Seedcornmaggotingreenbeanstem
Potato leafhopper isfrequentlyapestonbeans.Adultsareabout1/8 inch long,brightgreen,andwedge-shaped.Bothadultsandnymphsfeedbysuckingplantjuices.Toxinsintheleafhopper’ssalivacauseplantstostuntandleavestoyellowandturnbrown,aconditioncalled“hopperburn.”Leafhoppersoftenwillmoveoutofalfalfa intoothercropswhenalfalfaiscut.Leafhoppersshouldbecontrolledbeforehopperburnsymptomsappear.
J.Obermeyer
J.Obermeyer
J.Obermeyer
Potatoleafhopperadult,nymphs,anddamage
Flea beetlesmaychewsmallholesinbeanleaves.Thisdamagewillusuallybeworseinweedygardens.Thedamageis usually only important on seedling plants. Carbaryl willprovideadequatecontrolifneeded.
PurdueUniversity
Red-headedfleabeetleandcornfleabeetle
7 Managing Insects in the Home Vegetable Garden — E-21-W
Mexican bean beetlescanbeapestofbeansinsouthernandcentral Indiana.Theadultbeetle is roundandcoppercoloredwith16blackspotsonitsback.Itisabout5/16inchlongand1/4inchwide.Itiscloselyrelatedtothebeneficialladybeetles.Mexicanbeanbeetleslayclustersofoval,yelloweggsontheundersideofbeanleaves.Thelarvaeareoval,yellow,andcoveredwithbranchedspines.Bothadultsandlarvaefeedonleaves,pods,andstems.LaterplantingwillreducetheamountofMexicanbeanbeetledamage.Becausetheinsectsareslowmovingandhighlyvisible,handpickingcanbeasuitablecontrolmethod.Severalinsecticidesalsowillprovidegoodcontrol.
PurdueUniversity
Mexicanbeanbeetleadult,larva,pupa,anddamage
Bean leaf beetlesmayfeedonleavesandpodsinallareasofthestate.Adultbeetlesmayormaynothavespotsandmaycomeinseveralcolors,buttheywillalwayshaveablacktrianglebehindthehead.Beanscanusuallytolerateaconsiderableamountofleaffeedingwithnoeffectonyield.Beetlespresentwhenpodsareformingshouldprobablybecontrolled.
J.Obermeyer
PurdueUniversity
Beanleafbeetlesandpoddamage
Cruciferous Crops (Cabbage, broccoli, cauliflower, Brussels sprouts, radish, turnip) Mostcrucifersareattackedbythesamecomplexofinsectpests.Radishesaresucharapidlygrowingcrop(maturingin
about28days)thattheyarenotusuallyaffectedbyinsects,otherthanpossiblyafewcabbagemaggotsfeedingontheroots.Turnipsgrownfortherootsarealsounlikelytohaveanyseriousinsectproblems,otherthanrootmaggots. The first insect problem that will occur on crucifers isthecabbage maggot.Theadultfly,whichisslightlysmallerthanahousefly,emergesinlateAprilorearlyMay.Theylaywhiteeggsatthebasesofnewlysetplants.Theeggshatchintoleglessmaggotsthatmigrateandtunnelintotheroots.Theycausetheplantstoappearsickly,offcolor,orstunted,andmaycausethemtodie.Injuryisusuallymoresevereincool,wetconditions.Forthehomegardener,chemicalcontrolisusuallynoteffective.Anothergoodideaistoplantafewmoreplantsthanneeded,incaseafewarelosttocabbagemaggots.Fliesareattractedtodecayingorganicmatter,soexcessiveuseofmanureshouldbeavoided.
C.E
astman
Cabbagemaggotdamage
Flea beetles are almost always a pest of crucifers.Carbarylwill usuallyprovidesuitablecontrol.Aphidsmayattackallthecrucifers,aswell.Thenumberofaphidsmaybereducedbydestroyingcropresiduewhenthegrowingseasonhasendedandbyencouragingnaturalenemiessuchasladybeetles.Naturalenemiescanbeconservedifuseofchemicalinsecticidesiskepttoaminimum.
Palestripedfleabeetle
PurdueUniversity
R.K.C
hapm
an
Cabbageaphidsonleaf
C.E
astman
Cabbageaphiddamage
8Managing Insects in the Home Vegetable Garden — E-21-W
Asmostgardenersknow,themostseriousinsectproblemoncrucifersisthecaterpillars.Thereareactuallythreedifferentspecies of caterpillars that are serious pests of crucifers.Diamondback moth larvaearesmall(1/2inch),cigar-shapedgreencaterpillars thatwriggle rapidlywhen touched.Theypupateinlittlesilkencasesgluedtotheundersidesofleaves.Eachlarvadoesnotdoagreatdealofdamage,buttheycanoccurinextremelyhighnumbers.
caterpillars and treated when necessary, or Bt should beappliedonaweeklybasis.Thepyrethroid insecticidesarealsoquiteeffective.
Solanaceous Crops (Tomatoes, potatoes, peppers, eggplant) Solanaceous crops are attacked by a wide variety ofinsects.Severalofthesepestscanbequitesevereanddifficulttocontrol,asisindicatedinTable1.Thesecropsareoftendifficulttogrowsuccessfullywithoutusinginsecticides. ThemostnotoriousofallthepestsofsolanaceouscropsistheColorado potato beetle.Thisinsectfeedsonallfourtypesofsolanaceouscropsinboththelarvalandadultstages.Theadult isayellowbeetleabout1/2 inchlongwitheachwingcoverbearingfiveblackstripes.The larva is reddishwithablackheadandlegsand2rowsofblackspotsalongeachside.Overwinteringadultsfrequentlybeginfeedingonpotatofoliageassoonasitisaboveground.Bothadultsandlarvaefeedonalltheleaftissueexceptforthemainleafveinandstems.Therearetwogenerationsperyear.Theinstarguideonpage9willhelp thehomegardenerknowwhichinstarsarepresent.The larger instarswill consumemuchmorefoliageeachdayandarealsomuchmoredifficulttokillwithinsecticides.Therefore,itisimportanttomakeinsecticideapplicationswhenthelarvaearesmall(1stor2ndinstars).Inmanyareas,Coloradopotatobeetlesareresistanttomostinsecticidesavailabletohomeowners. Bacillus thuringiensisinsecticidesspecificallyforpotatobeetlescanbeeffectiveifappliedwhenlarvaearesmall(1stor2ndinstar).Otheravailablealternativetoinsecticidesinclude
J.W
yman
DiamondbackmothlarvaanddamageR.Foster
Theimported cabbagewormisthelarvalstageoftheverycommonwhitecabbagebutterflywithblackspotsonthewingtips.Thecaterpillarsarevelvety-greenandreachover1inchinlength.
Importedcabbagewormadultandlarva
W.C
ranshaw
W.C
ranshaw
Thecabbage looperdoesnotoverwinterinIndiana,butflieshereeachJune.Thelarvaearelightgreen,and,whentheycrawl,theymakeacharacteristicloopinthemiddleoftheirbody.Thesecondgeneration,whichoccursinAugustandSeptember,isthemostserious. Allthesecaterpillarsfeedontheleavesandcanreducetheplantgrowth.Themostseriousdamageistotheportionsofplantsthataretobeconsumed.Fortunately,goodcontrolcanbeachievedwithvariousformulationsofBacillus thuringiensis.Thismaterialisverysafeandwillnotharmbeneficialinsects.It ismuchmore effective on the young larvae.Therefore,plantsshouldbeinspectedonceortwiceperweekforyoung
Cabbagelooperanddamage
J.Obermeyer
S.M
ahr
W.C
ranshaw
W.C
ranshaw
Coloradopotatobeetleeggsandlarva
W.C
ranshaw Coloradopotatobeetleadult
Coloradopotatobeetledamage
W.C
ranshaw
9 Managing Insects in the Home Vegetable Garden — E-21-W
2 3 41
InstarGuideColoradoPotatoBeetle
Determineintowhichcirclethelarvafitsmostcompletelywithoutoverlappingtheborders.Thenumbercorrespondingtothatcircleistheinstarforthatlarva.
handpickingadultsofftheplantsanddestroyingthembeforetheybegintolaytheirorange-redeggsontheundersidesoftheleaves.Damagecanalsobereducedbyapplyinga4-6inchlayerofstrawmulchonbothsidesofthepotatorowrightafterhilling. Flea beetleswillattackallofthesolanaceouscrops,butcanbeparticularlydamagingtoeggplant.Fleabeetlesaresmall,hard-shelledinsects,sonamedbecausetheirenlargedhind legs allow them to jump like fleas from plants whendisturbed.Theirdamageisunusualinappearance.Theyfeedbychewingasmallholeinaleaf,movingashortdistance,thenchewinganotherhole,andsoon.Mosthealthyplantscantolerateaconsiderableamountoffleabeetledamage,andcontrolisobtainedeasilywithanumberofcommongardeninsecticides.RefertoExtensionpublicationE-74,Flea Beetles,foradditionalinformation.
Univ.W
isconsin
Fleabeetlesanddamage
Univ.W
isconsin
Thepotato leafhopperdescribed in thebeansectionisalsoapestofpotato,doingdamagesimilartothatdonetobeans.Leafhoppers cancausesubstantial yield lossatrelativelylowdensities.Treatmentisjustifiedifthereismorethanonenymphpertenleaves.Severalspeciesofaphidswillattacksolanaceouscrops.Fortunately,potatoesandtomatoescantolerateaconsiderableamountof feedingwithoutanyeffect on yield. However, aphids feeding on peppers cantransmitseveralviraldiseasesthatarequitedetrimentaltopepperplants.Peppers,therefore,shouldbekeptrelativelyfreeofaphids.
MichiganStateUniv.
Univ.W
isconsin
Potatoleafhoppernymphs,adult,anddamage
Severalcaterpillarsmaybefoundfeedingontomatoes.Thetobacco hornwormisaverylargegreenishcaterpillar(upto4inches)withaspineontherearendandwhitestripesonthesides.Larvaefeedonboththeleavesandthefruit,and,becauseoftheirlargesize,onelarvacandoaconsiderableamountofdamage.Hornwormsusuallydonotoccurinlargenumbers,sohandpickingisagoodmethodofcontrol.Theyareharmlesstohumans.
W.C
ranshaw
Tobaccohornworm
The tomato fruitworm (also thecorn earworm) is alate-seasonpest(August-September)thatboresintothefruit.Thelarvaevaryconsiderablyincolorfromlightgreentotan,brown,pink,maroon,ornearlyblack,withlightanddarkstripesrunninglengthwiseonthebody.Theyreachalengthofabout11/2inches.Theymaybecontrolledwithinsecticides,butusuallythedamagecanbetoleratedandthedamagedfruitsimplydiscarded.
G.B
rust
G.B
rust
Tomatofruitwormanddamage
10Managing Insects in the Home Vegetable Garden — E-21-W
Vine Crops (Cucumbers, melons, pumpkins, squash) Seedcorn maggots are closely related to cabbagemaggotsandwillattackallthevinecrops.Damageismoreserious if thecropsareplanted intoheavilymanuredsoil.Damageisalsomoresevereincoolweather.Plantswillgrowmorevigorouslyiftheyareplantedaslateaspossible.Also,plantingafewextraseedsperhillwillreducetheeffectofanyseedcornmaggotinjury.
G.B
rust
G.B
rust
Seedcornmaggotanddamage
Probably themost serious insect pests of vine crops,especiallycucumbersandcantaloupes,arethespottedandstriped cucumber beetles.Thespottedcucumberbeetleisgreenishyellowandhas12blackspotsonthewingcover.Thestripedcucumberisyellowwiththreeblacklinesrunningthelengthofthebody.Thelegsandundersidesarealsoblack.Thebeetlesfeedonstemsandleaves,butthemostimportantdamage they do is to transmit a bacterium that causes adiseasecalledbacterialwiltofcucurbits.Thediseaseplugsup the liquid-conducting tubeswithin theplantand resultsinthesudden,severe,andpermanentwiltofasingleplantrunnerortheentireplant. The onlyway to prevent the disease is to control thebeetles.Whentheplantsaresmall, theycanbeprotectedfrombeetlefeedingbycoveringtheplantswithasmallmeshmaterialsuchasabridalveilsupportedonastickwithdirtsealingtheedgesontheground.Ofcourse,whentheplantsstarttobloom,theclothmustberemovedtoallowbeestopollinatetheplants.Theothercontroloptionistoprotecttheplantswithaninsecticidewhenthebeetlesarepresent.
J.Obermeyer
R.Latin
A.York
Stripedcucumberbeetle Spottedcucumberbeetle
Earlysymptomsofbacterialwiltofcucurbits
Melon aphidsoccasionallybuildupontheundersidesoftheleaves,causingtheplantstobestuntedortowilt.Aphidsaremoreofaprobleminhot,dryweather.Naturalenemiesusuallywillkeepaphidsundercontrol,butmalathionorsoapwillprovideadequatecontrol.Spider mitesareanon-insectarthropodthatsuckplantjuicesfrommanytypesofplants.Theyarealsomoreofaprobleminhot,dryweather.Sprayingcarbaryl tocontrolotherpestswilloftenincreasemiteandaphidproblemsbykillingtheirnaturalenemies.
G.B
rust
G.B
rust
Melonaphidanddamagetowatermelon
Pumpkinsandsquasharemostseriouslyattackedbysquash bugs.Squashbugadultsarebrownish-blackbugsthatreachabout5/8inchinlength.Thenymphsarevarioussizesandarewhitishwithblacklegs.Bothnymphsandadultssucksapfromleavesandunripefruit,causingplantstowiltanddie,andfruittocollapse.Thenymphsoftenwillclustertogetherinlargegroups.Destroyingcropresiduewillreducetheproblemsyouwillhavenextyear.
J.O
bermeyer
J.Obermeyer
Squashbugeggs,nymphs,andadult
J.Obermeyer
11 Managing Insects in the Home Vegetable Garden — E-21-W
Thesquash vine borerisasporadicpestofsquashandpumpkins,butcanbeseriousattimes.Thedamageisoftenfirstapparentasthesuddenwiltingofanotherwisehealthyvineorplant.Massesofgreenish-brownfrasswillbepushedoutoftheentranceholeatthebaseoftheplant.Awhitegrub-likecaterpillarcausesthedamagebyboringintothevine.Theadultisaclearwingmoththatlookslikeawaspandisactiveinthedaytime.Theonlyin-seasoncontrolmethodistousetwoinsecticidesprays,7daysapart,beginningwhenthevinesstarttorun.Destroyingcropresiduewillalsoreducesquashvineborerproblemsnextyear.
PurdueUniversity
C.W
elty
R.Foster
Squashvineborerlarva,adult,anddamage
Sweet Corn TheEuropean corn borerattacksboththefoliageandtheearsofsweetcorn.Thelarvahasapalewhitebodywithseveralbrownorblackspotsandablackhead.Afewholesintheleavesofyoungcornplantsisnotacauseforconcern.Asubstantialamountofdamagetowhorlstagesweetcorncanbetoleratedwithoutanyeffectonyield.Europeancornborerscanbecontrolledbytreatingwithaninsecticidewhenthetasselsbegintoemerge.Oneortwoapplicationsspacedfivedaysapartwillusuallyprovideadequatecontrol.Thecorn earwormisthesameinsectthatwecallthetomatofruitwormwhenitoccursontomatoes.Itsdamageismostlylimitedtotheears,usuallytheeartips.Controlofcornearwormscanbeachievedbysprayingthegreensilksanddevelopingearswithpyrethroidinsecticides.Bacillus thuringiensis insecticidesshouldnot beused for cornearworms; theydonotwork.Mostofthedamageisusuallyconfinedtothetipsoftheearsandcanbesimplycutoff,eliminatingmuchoftheneedforinsecticides.
Europeancornboreranddamage
J.Obermeyer
Cornearworm
J.Obermeyer
BENEFICIAL ARTHROPODS Onlyaverysmallpercentageoftheinsectsthatoccurin Indianaarepests,andonlya fewof thesearepestsofvegetables. Most insects are so innocuous that they areseldomnoticed.Manyprovidefoodforlargeranimals,helpbreakdowndecayingplantsandanimals,etc. Otherinsectsprovidedirectbenefitforgardeners.Anumberofinsectsandotherarthropodsarepredators;thatis,theyeatotherinsectandmitepests.Predatorsincludespiders,adultandimmatureladybeetles,adultandimmaturelacewings,preyingmantids,somestinkbugs,andgroundbeetles.Otherinsectsactasparasitesonpestinsects.Theseincludeanumberofspeciesofwaspsandflies,whichlayeggsinoronthehostinsect.Thus,itisimportanttoconserveasmanypredatorsandparasitesaspossible.Often theywill control thepestspecieswellenoughthatadditionalcontrolisnotnecessary.Agoodmethodforconservingbeneficialinsectsistosprayinsecticidesonlywhennecessaryandtochooseinsecticidesthatareleasttoxictothebeneficialinsectswheneverpossible. Oneofthemostnotablebeneficialinsectsisthehoneybee.
12Managing Insects in the Home Vegetable Garden — E-21-W
Besidesprovidinghoney,beesserveaspollinatorsformanyofourvegetableandfruitcrops.Withoutthesepollinators,manycropswouldneverproducefruit.Insecticidesthataretoxictobeesshouldneverbeappliedwhenplantsareinbloom.
Ladybeetleadultandlarva
J.Obermeyer
Brianchristine
J.Obermeyer
W.C
ranshaw
Predaceousstinkbug Groundbeetle
BrianChristine
BrianChristine
Lacewinglarva Greenlacewingadult
J.Obermeyer
Parasitizedaphidmummy
J.Obermeyer
Jumpingspider
J.Obermeyer
Parasitizedhornworm
J.Obermeyer
Honeybee
READANDFOLLOWALLLABELINSTRUCTIONS.THISINCLUDESDIRECTIONSFORUSE,PRECAUTIONARYSTATEMENTS(HAZARDSTOHUMANS,DOMESTICANIMALS,ANDENDANGEREDSPECIES),ENVIRONMENTALHAZARDS,RATESOFAPPLICATION,NUMBEROFAPPLICATIONS,REENTRYINTERVALS,HARVESTRESTRICTIONS,STORAGEANDDISPOSAL,ANDANYSPECIFICWARNINGSAND/ORPRECAUTIONSFORSAFEHANDLINGOFTHEPESTICIDE.
Revised 5/2010
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