PestWatch Report on July 18, 2017

Corn earworms are low in most locations, European corn borer infestations are spotty, and fall armyworm immigration has started.
PestWatch Report on July 18, 2017 - News

Updated: October 31, 2017

PestWatch Report on July 18, 2017

European corn borer larvae (left) adults (right). Photo: ©Marlin E. Rice

Corn earworm

Corn earworm (CEW) trap counts have decreased. It appears that we had an overwintered population resulting in some high counts in June/early July. I expect those adults to be in a larval or pupal stage now. Current counts are more like the summer lull we get before significant migration from the south. This year, we may see a combination of that migration plus a 2nd generation from the overwintered population, so trap counts could increase, but right now most sites are below threshold, or at a wide (5-6 day) threshold. Sites at that wide spray threshold level are in Centre, Lancaster, Lehigh, and Westmoreland County.

European corn borer

European corn borer (ECB) is starting to emerge as second generation adults. Infestations are spotty, but noticeably high in Clinton and York County.

Fall armyworm

Fall armyworm (FAW): We continue to see low rates of trap capture, with an increasing number of sites. Early immigration appears to be occurring now. It is not uncommon to find damage prior to trap capture at this time of year. Check for larval feeding in vegetative corn: large, ragged damage to leaves with lots of frass.

Summary

CEW are low in most locations, at no-spray of a wide (5-6 day) spray threshold. ECB infestations are spotty - 2nd generation adults are in sites at Clinton and York Counties. FAW immigration has started. Silking corn will be very attractive to early-season CEW moths.

CountyFarm/Trap Name

CEW
4-Jul

CEW
11-Jul
CEW
18-Jul
ECB
4-Jul
ECB
11-Jul
ECB
18-Jul
BlairCurryville, PA1683006
BlairHollidaysburg, PAnull00null00
BlairTyrone, PAnull103null00
BradfordBristol's Produce000430
BradfordLarue's Produce2009897
BradfordShores Sisters Produce01001320
BucksBedminster00null00null
BucksBuckingham6308411
CentreHarner05.340.72.60
CentreRock Springs14.41.6000
CentreStormstown9.117.511000
ClintonLoganton002.61.2016.6
FayetteDuda's Farm Inc.2008005
HuntingdonNew Morning Farm77nullnull5.3null
IndianaBrush Valley10null00null
IndianaCreekside224null
LackawannaRansom4nullnull3nullnull
LancasterLandisville3316101
LancasterNeffsville02null03null
LancasterNew Danville274156
LehighGermansville241317000
LuzerneDrums30null00null
LuzernePlainsnull0nullnull7null
LycomingLinden0.9null0
LycomingMontoursville28null0
LycomingMuncy2.620.24.7
MontourMontour6101363
NorthamptonNazareth0null00null0
SchuylkillTower City101001
WashingtonVenetia161847
WestmorelandSchramms Farms and Orchardnullnull21.5nullnull0.9
YorkYork86381431

Thresholds

Reproductive (tassel/silk) and late vegetative corn attracts moths. Shorten spray schedules when populations increase.

Thresholds Based on CEW Captures

LevelsCEW catch / weekSpray frequency
almost absent1-134 days to no spray
very low14-355 to 6 day
low36-704 to 5 day
moderate71-3493 to 4 day
high> 3502 to 3 day

If CEW is low, then consider ECB

LevelsECB catch / weekSpray frequency
almost absent< 14no treatment
very low15-356 day
low38-705 day
moderate> 704 day
high

Authors

Insect population dynamics IPM

More by Shelby Fleischer, Ph.D.