Corn earworm moth black light trap catches were low this week, averaging from 2 to 6 per night (Greensville=3; Hanover=2; Southampton=6; Suffolk=2). Most trap operators will be shutting off their traps by the end of this month. We greatly appreciate the efforts of cooperating growers, Virginia Cooperative Extension Agents Mike Parrish, Sara Rutherford, Laura Maxey-Nay, Scott Reiter, and Josh Holland, and Tidewater Agricultural Research and Extension Center’s Daniel Espinosa. TABLE
With the exception of Hanover, trap captures have declined since last week. The average nightly corn earworm/bollworm moth black light trap captures for this week (rounded) were: Greensville=18; Hanover=7; Prince George-Templeton=3; Prince George-Disputanta=2; Southampton=8; Suffolk=38. Thanks to our trap operators for their reports! TABLE
Average nightly corn earworm/bollworm moth black light trap captures for this week were: Greensville=28; Prince George-Templeton=5.5; Prince George-Disputanta=7; Southampton=17; Suffolk=76. Here is the Table
For soybean, here is the tool that calculates the corn earworm larval threshold number based on user input values for sampling techinque (sweep net or beat cloth), cost of insecticide application, price of beans, and row width: threshold calculator
We have done 391 vial tests so far this season, with 35% of moths surviving the 24-hour exposure to the pyrethroid cypermethrin at the rate of 5 micrograms per vial.
Average nightly corn earworm/bollworm moth black light trap captures for this week were: Dinwiddie=54; Greensville=15; Prince George-Templeton=13; Prince George-Disputanta=11; Southampton=22; Suffolk=92. Here is the Table
We have 37% survival in our cypermethrin vial tests (338 corn earworm moths tested from Suffolk, VA).
Average nightly corn earworm/bollworm moth black light trap captures for this week were: Dinwiddie=51; Greensville=9; Hanover=3 (first week with more than 0.5 per night); Prince George-Templeton=12; Prince George-Disputanta=3; Southampton=5; Suffolk=17. Here is the Table. At just over 200 vial tests conducted, corn earworm moth survival is 39%.
Average nightly corn earworm/bollworm moth black light trap captures for this week were: Dinwiddie = 26; Greensville =4; Prince George-Templeton = 9; Prince George-Disputanta = 6; Southampton = 8; Suffolk = 23. Thanks to our Agents and Growers for their efforts. Here is the data table
Sally Taylor and her entomology program sampled a Cotton Incorporated sponsored planting date experiment today at the Tidewater AREC in Suffolk, VA. We found 2 to 6.5% bollworm-injured bolls in conventional (non-genetically protected against bollworm) cotton. In our Virginia Soybean Board experiment with maturity groups 4 and 5 full-season soybean (beginning pod growth stage), we had 2.3 to 5 corn earworm larvae and up to 3 soybean looper larvae per 15 sweeps.
Average nightly moth captures for this week were: Greensville =10; Prince George-Templeton = 3; Prince George-Disputanta = 7; Suffolk = 21. Here is the data table
Black light trap nightly averages for corn earworm/bollworm moths this week in Virginia were: Greensville = 35.6; Prince George-Templeton = 1.0; Prince George-Disputanta = 3.3; Southampton = 2.0; Suffolk = 17.1 (all reports were higher than last week). Thanks to our Agents for their reports.
Resistance monitoring of corn earworm/bollworm using adult vial tests now has 50% of moths surviving the 24-hour exposure to the pyrethroid, cypermethrin at the 5 microgram/vial rate (76 vials tested to date, collected from Suffolk).
Prior to this week, corn earworm/bollworm moth counts have been low in southeast Virginia black light traps. For this week (July 17-23), average nightly catches of moths were: Greensville = 7.4; Prince George-Templeton = 0.3; Prince George-Disputanta = 0.7; Southampton = 1.5; Suffolk = 7.4. Thanks to the Virginia Cooperative Extension Agents who are operating traps this season.
We have tested 47 corn earworm/bollworm moths since June 23, 2020 in our pyrethroid resistance monitoring program. Moths are captured in pheromone traps and are exposed to 5 micrograms of cypermethrin inside a glass vial for 24 hours, then rated as dead/down/alive. Untreated controls (in acetone-only treated vials) are also evaluated to correct for control mortality. The average for the past month is 43% moth survival. High survival rates indicate an increased chance of pyrethroid control issues and the need to consider alternative chemistries if a spray is needed.
In a non-Bt corn experiment planted on April 9 at our research farm in Suffolk, VA, we had large corn earworm larvae in the ears last week. Now they have exited the ears and are pupating in the soil. It takes about 10 days for the moths to emerge–this flight out of corn is the one that we are concerned with in crops such as soybean, cotton, peanuts, and vegetables–the moths want to lay eggs on a good food source for their larvae. Please check back with the Advisory for more pest updates and recommendations.