Number 4 ‐ May 18, 2015 Modified Growing Degree Days (Base 50

Number4‐May18,2015
ModifiedGrowingDegreeDays(Base
50°F,March1throughMay14)
Station
Location
Freeport
St.Charles
DeKalb
Monmouth
Peoria
Champaign
Springfield
Brownstown
Belleville
RendLake
Carbondale
DixonSprings
Actual
Total
331
325
328
437
457
481
565
530
604
662
618
641
Historical
Average
(11year)
277
267
307
351
384
386
433
485
510
556
528
575
One‐
Week
Projection
402
391
405
521
543
571
665
632
710
773
722
751
Two‐
Week
Projection
478
461
488
606
629
664
767
739
821
891
833
867
Insectdevelopmentistemperaturede‐
pendent.Wecanusedegreedaystohelp
predictinsectemergenceandactivity.
Home,Yard,andGardenreaderscanuse
thelinksbelowwiththedegreedayac‐
cumulationsabovetodeterminewhat
insectpestscouldbeactiveintheirarea.
GDDofLandscapePests
GDDofConiferPests
Degreedayaccumulationscalculated
usingtheIllinoisIPMDegree‐DayCalcu‐
lator(aprojectbytheDepartmentof
CropSciencesattheUniversityofIlli‐
noisandtheIllinoisWaterSurvey).
(KellyEstes)
DiplodiaTipBlightonPine
ThePlantClinichasreceivedanumber
ofpinesampleswithvariousailments
thisspring.Diplodia(alsoknownas
Sphaeropsis)TipBlighthascontinuedto
beacommondiagnosisonAustrian,
Scots,andotherpines.Itcanalsoaffect
spruce,fir,Douglasfir,cedar,arborvitae,
andjuniperplants,thoughthediseaseis
muchlesscommononthesehosts.Dip‐
lodiaTipBightisconsideredastress
diseasebecauseitismuchmorecom‐
mononplantsunderstress.Thepatho‐
genisafunguswhichcausesbothanee‐
dleblightandcankeringofthebranches
leadingtoveryuglytreeswhich,ifthe
diseaseisallowedtocontinueforsever‐
alyears,maysuccumb.
Diplodiacanbeabittrickytodiagnosein
thefieldasthereareanumberofneedle
blightsinIllinoisandmicroscopicobser‐
vationofsporesisneededforadefinite
confirmationofthepathogen.However,
therearesomecharacteristicsymptoms
thatareassociatedwiththedisease.
TipBlight:Asthenameofthedisease
implies,Diplodiacausesablighting,or
browningofnewneedles.Inmostsitua‐
tions,thefungusonlyaffectscurrent‐
seasonneedles,shoots(candles),and
cones.Ontreeswithnewinfections,this
resultsinbrancheswithgreen,livingold‐
erneedlesandbrown,deadnewgrowth.
Treesthathavebeeninfectedformultiple
seasonswilllosethegreenneedlesover
timeandeventually,alltheneedlesre‐
mainingonthebranchwillbebrown.
FruitingStructures:Thisdiseaseis
causedbyafungalpathogen.Whilethe
sporesaremicroscopic,thefruiting
structurescanbeseenwiththenaked
eyeoramagnifyingglass.Fruitingstruc‐
turesareoftenfoundonmaturepine‐
cones.Thesestructuresareeasytospot
onthescalesofthepinecones.
Fruitingstructuresmayalsoappearon
dyingneedles.However,Iseethestruc‐
turesmuchmorecommonlyonthe
pineconesthanontheneedles.Isuspect
thatenvironmentalconditionsandthe
longevityoftheinfectiononthehost
mayplayapartindeterminingifthe
fruitingstructuresformontheneedles.
Cankers:Iftheinfectioncontinuesfor
severalyearswithoutbeingmanaged,
cankersmayformonaffectedbranches.
Thesecankerscanbedifficulttosee.
Theyappearasdistortedwoodandthey
mayproduceawhite,stickyexudate.As
withanycanker,itdisruptstheflowof
waterandnutrientswithintheplantand,
ifitfullygirdlesthebranch,canleadto
thedeathofalltissuebeyondthecanker.
ManagementforDiplodiaTipBlightrelies
onsanitationandfungicidesprays.Pine‐
conesshouldbecollectedandremovedas
theyfall.Infectedbrancheswithcankers
shouldbeprunedoutofthetreeindry
weather.Fungicidescontainingtheactive
ingredientspropiconazole,thiophanate‐
methyl,copper,mancozeb,ormyclobu‐
tanilarelabeledforusetomanageDiplo‐
diaTipBlight.Thespraysmustbeapplied
threetimesinaseasontoachievegood
control:whenbudsbegintoswelland
elongate,justbeforethenewneedles
emergefromthesheath,and10to14
dayslater.Affectedtreesshouldalsobe
mulchedlightlyandwateredduringperi‐
odsofdrynesstoreducestressonthe
tree.Ifcaughtearly,thisdiseasecanbe
managed.However,asthediseasepro‐
gresses,itfurtherweakensthetreeand
damagesitsaestheticvalue.(DianePlewa)
BronzeBirchBorer
Bronzebirchborerisanativespeciesin
thesamegenusasemeraldashborerand
attacksthetreeinasimilarmanner,ex‐
ceptthatitattacksbirchesinsteadofash.
Bronzebirchborerattacksmostly
nonnative,white‐barkedbirchesastheir
growthstartstoslowdown,typically
whenthetreesreach10ormoreyears
old.Itattacksyoungertreesthatareme‐
chanicallydamagedorplantedinpoor
sites.Nativewhite‐barkedbirchesareat‐
tackedmuchlaterinlife,astheydecline
intooldage.Whitespire,avarietyofan
Asianspecies,isresistanttotheborer,but
manyotherAsianandEuropeanvarieties
andspeciesareverysusceptibletoattack.
TheNorthAmericannativeriverbirches
arealsoresistanttoattack,andHeritageis
avarietyofriverbirchcommonlyplanted
becauseofitslight‐coloredbark.
Adultbronzebirchborerbeetleslayeggs
underloosebarkandinbarkcracksnear
thetopofthetree.Thehatchinglarvae
tunnelthroughthecambium.Ifthetun‐
nelingcirclesthestem,thisgirdlingkills
thestembeyondthatpoint.Leavesturn
brownandfalloff.Earlyattackisrecog‐
nizableasdead,leaflessbranchesatthe
topofthetree.Insubsequentyears,the
beetlesattacklowerandloweronthe
treeuntiltheentiretreedies.
Bronzebirchborerlarvaeareelongate,
white,andflattened,withobviousbeadlike
segments.Fullygrownlarvaeareabout1
inchlong.Thelarvaefeedthroughthe
summer,overwinteraslarvae,andpupate
inthecambiumareainspring.Although
thelifecyclecanbecompletedin1year,a
2‐yearlifecycleismorecommon.
AdultbeetlesemergethroughD‐shaped
holesduringvanhouttespireabloomin
midspring.Cross‐sectionsofadultbee‐
tlesareflatteneddorsalllyandrounded
ventrally,thatis,D‐shaped.Theyare
about1/2inchlongandappearbullet‐
shapedfromabove,beingquadratein
frontandtaperedposteriorly.Asthe
nameindicates,theyarebronzeindirect
sunlightbutappearblackishinindirect
light.Theadultbeetlesfeedontheleaves
ofalder,poplar,andbirch,butthisfeed‐
ingisnotsevere.
Itisnowtimetotreatforbronzebirch
borerthroughoutthestate.Theideal
applicationtimeforsystemicinsecticide
applicationis30daysbeforebeetle
emergence,butacceptablecontrol
shouldstillbepossibleeveninsouthern
Illinoiswherethebeetleswillhaveal‐
readyemerged.Effectivecontrolin‐
cludesemamectinbenzoate(Tree‐age)
asatrunkinjection,imidacloprid(Merit,
IMA‐jet,Imicide,Xytect)asatrunkinjec‐
tion,soilinjection,orsoildrench,and
dinotefuran(Safari)asatrunkspray,
soilinjection,orsoildrench.(PhilNixon)
PineNeedleScale
Pineneedlescaleisaseriouspestofpines
throughoutthestate,killingbranchesand
entiretrees.ItismostprevalentonScots
andmugopinebutiscommononmany
otherpinespecies.Italsoisfoundon
spruceandhemlockandislikelytocause
diebackonspruce.Itisprobablymostse‐
rioustoChristmastreegrowersbutcom‐
monlykillslandscapeplantsaswell.
Pineneedlescaleappearsaselongate,
whiteinsectsabout1/8inchlongonpine
needles.Thereisasmall,tanareaatone
end.Numberscommonlybuildupuntil
thefoliageappearswhitishfromadis‐
tance.Inthesehighpopulations,branches
andevenentiretreescanbekilled.Pine
needlescaleoverwintersaseggs.Eggs
hatchintobrickredcrawlersasvanhoutte
spireaisinfullbloom.Thecrawlers,first‐
stagenymphs,roamonthefoliagebefore
settlingdowntofeedandaresusceptible
toinsecticideapplications.Theysecretea
white,waxysubstancethatcoversand
protectsthescalefromdesiccation,natu‐
ralenemies,andinsecticides.Overseveral
moltsunderthewaxycovering,thescale
losetheirlegs,eyes,andantennae,becom‐
ingaprotectedsuckingblob.
Adultleglessfemalesremainundertheir
waxycoverings,butadultmalesemerge
astiny,two‐wingedinsects.Theseexist
onlytofertilizethefemales,havingno
mouthparts,sotheydieafteronlyafew
days.Matedfemalesfilltheareaunder
thewaxycoveringwitheggsanddie.
Theseeggshatchintoasecondgenera‐
tionofcrawlerssusceptibletoinsecti‐
cideapplicationwhenhillsofsnowhy‐
drangea,Hydrangeaarborescens
“Grandiflora”,blossomsturnfromwhite
togreen.Also,QueenAnne’slaceorwild
carrot,Daucuscarota,isinbloomatthis
time.Thesescalegrowthroughoutthe
restofthesummer,moltingintoadults
andproducingeggsthatoverwinter.
Beinganarmoredscale,theseinsects
suckoutthecontentsofindividualcells
anddonotproducehoneydew.Severely
attackedfoliageturnsyellowish,even‐
tuallydies,andturnsbrown.Itiscom‐
monforthisscaletobenumerouson
onlyonebranchoronesideofthetree.
Inlandscapes,ittendstoappearfirston
thesideofthetreenexttoabuilding.On
Christmastreefarms,onlyoccasional
treesmaybeinfestedoruninfested,de‐
pendingontheseverityoftheinfesta‐
tion.Whenscouting,besuretocheckall
sidesofalandscapetree,andbesureto
checktheentirefieldinanurseryor
Christmastreefarm.
Applicationofacephate(Orthene),
bifenthrin(Onyx,Talstar),cyfluthrin
(Tempo),insecticidalsoap,orsummer
oilshouldbeeffectiveifappliedwhen
thecrawlersareactive.Oneapplication
istypicallysufficientatthistimeofyear.
Ifinsecticidalsoaporsummersprayoil
isused,applyasecondspray7to10
daysafterthefirstsprayduetotheir
shortresidualeffects.Thesecondgener‐
ationofcrawlersemergesoveralonger
period,soanyinsecticideapplication
shouldberepeatedafter7to10days.
Realizethatsummersprayoilremoves
thebluebloomfromColoradoblue
spruce,resultinginagreenspruce.
Deadscaledonotfalloffoftheneedles.
Theeasiestwaytodeterminecontrolisto
lookforscaleonthecurrentyear’sgrowth
oncetheneedleshavematured.Thisis
mosteffectiveasanend‐of‐seasonevalua‐
tion.Youcanalsodeterminecontrolwith
ahandlensormicroscope.Usinganeedle,
youcaneasilyflipoffthewaxycoveringto
revealthescaleinsectbelowit.Brown,
shriveledscalearedead;plump,smooth
scalearealive.Realizethatanumberof
scalemustbecheckedbecausedeadscale
frompreviousyearswillstillbepresent.
(PhilNixon)
ElmLeafBeetle
Elmleafbeetlelarvaearepresentin
southernandcentralIllinois.Thispestis
lesscommoninnorthernIllinoisbut
larvaeshouldbepresentbytheendof
themonth.Theselarvaecanbeserious
leafskeletonizersofelmandzelkova.In
general,Europeanelmsareattacked
heaviestincludingSiberian(Ulmuspu‐
mila),English(U.procera),and“urban”
(U.pumilaXU.hollandicaXU.carpini‐
folia)elms.Chineseelm(U.parvifolia)is
usuallyonlylightlydamaged,with
Americanelm(U.americana)feeding
damageintermediatebetweenChinese
andEuropeanspecies.
Younglarvaearegraytoblackandwin‐
dowfeedbyeatingtheleaf’slowersur‐
faceandinterior,leavingtheuppersur‐
faceintact.Althoughthiswindowfeeding
isinitiallycleartowhitish,theexposed
cellsdieandturnbrown.Heavilyat‐
tackedtreesarecoveredwithbrown
leaves.Maturelarvaeareabout1/4inch
long.Theyareyellowwithablacklateral
stripeoneachside.Largelarvaeskele‐
tonizetheleaves.Fullygrownlarvae
formbrightyellowpupaeinbarkcrevic‐
esandatthebaseofthetree.
Adultbeetlesareabout1/4inchlong.
Theyareyellowwithblacklinesdownthe
middleofthebackandalongeachside.
Theyeatroundishholesintheleaves;
heavyinfestationsdefoliatetreesthrough
skeletonizingtheleaves.Adultslay¼inch
longoblongmassesofyelloweggsonthe
leafundersides.Therearetwotothree
generationsperyear,withthreegenera‐
tionsinsouthernIllinois.Adultsoverwin‐
terunderloosebark.Overwinteredadults
haveadullappearanceasthebrightyel‐
lowofthenewlyemergedadultturnsan
olivegreenoverthewinter.
Insecticidalsoapcanbeusedtocontrol
younglarvae,butisnotaseffective
againstolderlarvae.Acephate(Orthene),
carbaryl,(Sevin),imidacloprid(Merit),
lambda‐cyhalothrin(Scimitar,Demand),
andspinosad(Conserve)areeffectiveas
spraysagainstalllarvalstagesandadults.
Imidaclopridisalsoeffectiveasasoil
drenchorinjection.(PhilNixon)