Sweetcorn insect pest monitoring across VA for week of Aug 20, 2017

Large corn earworm larva in sweet corn soon getting ready to exit the ear to pupate in the ground.

Monitoring sweet corn for pest moth activity can help reduce the number of insecticide applications.  At Kentland Farm in Whitethorne, VA, we recently harvested the first of several tests, where we followed an IPM approach and compared it to sprays of the pyrethroid lambda-cyhalothrin 3 times per week during silking.  We saw no difference in the level of control from an IPM approach- only spraying when needed and spraying the diamide Coragen first compared with the frequent lambda pyrethroid sprays.   We will be harvesting multiple sites for this experiment and will share these when all of the data are in.  Commercial sweet corn farms are being monitored around Virginia for corn earworm and fall armyworm.  Moth Trap Catch Data are being recorded by:  Katlyn Catron  (Montgomery Co.); Jason Cooper (Rockingham Co.); Ursula Deitch (Northampton Co.); Helene Doughty (Accomack Co. & Virginia Beach); Kenner Love (Rappahannock Co.); Laura Maxey Nay (Hanover Co.); Steve Pottorff (Carrol Co.); Stephanie Romelczyk  (Westmoreland Co.); Laura Siegle (Amelia Co.); Rebekah Slabach (Halifax Co.); and Mark Sutphin (Frederick Co.).

This week we continued to observe moderate (above threshold) corn earworm moth catch at many locations, to warrant continued spraying.  Some of the areas with the highest CEW activity continue to be the Eastern Shore, and Frederick Co.; however, CEW moth catch has increased in Westmoreland, Rockinham, and Hanover Co.   We still have seen few to no fall armyworm moths yet. For corn earworm, moth trap catch of less than 1 per night means  low pest pressure and sweet corn sprays can probably be spaced 5-6 days apart during silking.  However, a catch of >1 or >13 moths per night means moderate and high pest pressure, respectively, and a more frequent spray interval (every 3 or 2 days) is justified.  Here are the trap catch results (moths per night) for several locations around Virginia for this week (note we do not have data for all locations):

Week of Aug 20 (avg)
Region County Field CEW/night FAW/night
Eastern Shore Accomack ESAREC – cemetery 1.4 NA
Eastern Shore Accomack ESAREC – woods NA NA
Eastern Shore Accomack ESAREC – sweet corn 1.4 0.2
Eastern Shore Northampton Bridge Tunnel 8.4 NA
Eastern Shore Northampton Capeville 1 1.3 0
Eastern Shore Northampton Cape charles 1.1 NA
Eastern Shore Northampton Eastville 5.3 0.2
Eastern Shore Northampton Nassawaddox 0.6 0.4
Virginia Beach Virginia Beach Pungo 1 NA NA
Piedmont Amelia Field 1 NA NA
Piedmont Hanover Farm 1 3.4 0.4
Piedmont Hanover Haynes NA NA
Northern Neck Westmoreland Field 1 7.0 0.6
Northern Neck Westmoreland Field 2 NA NA
Shenandoah Valley Rappahannock Field 1 3.5 0
Shenandoah Valley Page Field 1 NA NA
Shenandoah Valley Frederick Farm 1 5.6 0
Shenandoah Valley Frederick Farm 2 14.4 0
Shenandoah Valley Rockingham Farm 1 6.4 0
Shenandoah Valley Rockingham Farm 2 NA NA
New River Valley Montgomery KC NA NA
New River Valley Montgomery KO1 NA NA
New River Valley Montgomery KO2 NA NA
New River Valley Montgomery WF1 NA NA
New River Valley Montgomery WF2 NA NA
New River Valley Montgomery WF3 NA NA
New River Valley Montgomery WS1 NA NA
New River Valley Montgomery WS2 NA NA
New River Valley Montgomery WS3 NA NA
Southwest Carroll NA NA