Updated corn earworm moth catches from our pheromone trap network are in this Table. Prince George County’s black light had 11 total moths over the past 8 nights, but high numbers were caught in that county’s pheromone trap (averaging 42.5 per night over the past 8 nights).
Today in a project supported by USDA-NIFA Crop Protection and Pest Management’s Extension Implementation Program, our entomology crew sampled cotton in Suffolk, VA with no genetic protection against bollworm and found 14% boll injury due to this pest in the insecticide-untreated plot. There was no boll injury due to bollworm in the insecticide-untreated WideStrike or Bollgard 3 plots.
Recently, soybean aphids have been confirmed at higher populations than typically expected in August. While many folks are scouting for worms and stinkbugs, we also recommend looking for aphids in your soybean fields as well. The key variables to consider regarding managing soybean aphids are the number of aphids per plant and the soybean growth stage. Information from our Pest Management Guide on Soybean Aphids in summary including info on thresholds and sampling are as follows (VCE Field Crops PMG, Publication 456-016):
Number of aphids per soybean plant
The current economic threshold for aphids is an average of 250 aphids per plant, on two consecutive field visits spaced about 5-7 days apart. This is because aphid populations can “crash” quickly due to heavy pressure by natural enemies like lady beetles, parasitic wasps, and fungal diseases. When scouting, choose a “Z” or “W” shaped pattern to cover the entire field and sample at least 20 to 30 plants per field by examining the entire plant, including stems and upper and lower leaf surfaces. Use the aphid/plant average for determining the need for treatment.
The soybean growth stage
The threshold of 250 aphids per plant applies to soybeans through the R5 growth stage (3 mm long seed in the pod at one of the four uppermost nodes on the main stem), after which time plants can tolerate 1,000+ aphids with no threat to yield. If an insecticide is applied for aphids, pyrethroids (e.g. bifenthrin, Warrior II, Mustang Max, etc.) can be effective for management, but choosing a more selective insecticide can preserve natural enemy populations and limit future flare ups of aphids or other pests.
The August 2025 corn earworm moth pheromone trap data (to date) can be found in Table 3. Some of the higher catches occurred in Brunswick, Prince George, and Rockbridge, VA. Last month’s data can be found in Table 2. Scott Reiter’s black light trap in Disputanta captured a total of 30 moths this week (6 nights).
We’ve evaluated 470 moths in our cypermethrin vial tests, with 48% dead/down after a 24-hour exposure to this pyrethroid insecticide at the 5 microgram/vial rate.
With as hot as it’s been in July, it’s hard to imagine Sclerotinia blight showing up in peanuts. I have been searching for it in my trials but haven’t seen it yet. However, highs in the low 80s and lows around 70 today through next week means conditions will be favorable for disease development. Plus, adequate soil moisture is present due to recent rains and peanut canopies are dense enough to favor Sclerotinia blight. I recommend monitoring the Virginia Sclerotinia Blight Advisory on the Peanut Cotton InfoNet to check the risk of this disease in your area and scout for disease, especially in fields with a history of Sclerotinia blight. Access the Peanut Cotton InfoNet using this link https://infonet.ext.vt.edu/. You can also call the VA Peanut Hotline at 1-800-795-0700 for up-to-date disease advisories.
At this point in the season I recommend fungicides Omega or Vantana tank-mixed with a leaf spot fungicide if you haven’t already applied Miravis + Elatus. I hesitate to recommend the first application of Miravis + Elatus this late in the season due to concerns about late leaf spot escapes as these products have no curative activity against leaf spot. You’re okay if it’s the second application. Fontelis at 1.5 pt/acre can provide some disease suppression if sprayed preventively.
Please contact me if you have questions.
David Langston. (757) 870-0498 cell email: dblangston@vt.edu
Pheromone trap catches of corn earworm (=bollworm) moths are available in this Table. The Prince George black light trap averaged approximately 13 moths per night this week and that county also had high pheromone trap catches. A peanut field at the Tidewater Agricultural Research and Extension Center in Suffolk, VA hit corn earworm larval threshold numbers (8 larvae per drop cloth sample) and we dropped in an insecticide efficacy experiment. We were finding 2.5 bollworm eggs per 100 cotton terminals this week in Suffolk. Our cypermethrin adult vials tests indicate 44% dead or dying moths after a 24-hour exposure to this pyrethroid insecticide (n = 340 moths tested from Suffolk).
Corn earworm moth pheromone trap catches started to increase this week in some counties where captures have previously been low. The highest nightly averages were Brunswick (47), Prince George (30), Accomack (20), Greensville (15), Virginia Beach (13), and Southampton (11). Here is the Table. Black light trap catches at Prince George (Disputanta) averaged 3 per night. Cypermethrin vial test results are 53% dead or down moths after a 24-hour exposure to this pyrethroid insecticide at the rate of 5 micrograms per vial (n=178 moths tested). I found a bollworm egg in cotton on July 23 in Suffolk, VA.
Corn earworm moth nightly pheromone trap catches ranged from zero to 9 per night this week (here is the Table). Black light traps averaged 1.8 per night in Petersburg and 1.3 per night in Disputanta.
In our corn earworm adult vial tests with the pyrethroid cypermethrin (5 micrograms/vial rate), 62% of moths were dead or knocked down after a 24-hour exposure (64 moths from Suffolk, VA have been tested to date). We will continue to provide weekly updates on trap catches and vial test results.
We hit the tarnished plant bug threshold for the first time this season on July 15 at the Tidewater AREC, in Suffolk. Reports of threshold numbers are rolling in from collaborators as well. Here are a few key reminders for successful plant bug management this year;
1. Use economic thresholds
These economic thresholds are the point at which you will see a return on investment from spraying for plant bugs.
Pre-bloom threshold;
8 plant bugs/100 sweeps AND less than 80% square retention
Many of our cotton fields here on the research farm and in on-farm trials are beginning to flower this week. Once you reach 50% of plants in a field with flowers, switch to using a drop cloth to sample plant bugs. The drop cloth should be placed on the ground between two rows and the plants on either side vigorously beaten over top of the sheet. Take a sample in 6-8 spots throughout a field and average to determine the number of bugs per drop cloth sample. Making the switch from sweep net samples to drop cloth samples during bloom is critical for making informed management decisions on plant bugs.
Threshold from the 1st week of bloom on;
3 plant bugs/5 row feet
Even if you are using a Thryvon cotton variety, it still needs to be scouted and treated for plant bugs at the recommended thresholds. Weekly scouting will provide the best insight on when and where insecticide applications are needed.
2. Insecticide rotation
Hold off on using strong broad-spectrum insecticides until late in the season. These include pyrethroids and organophosphates;
Organophosphates: Bidrin, Orthene
Pyrethroids: Warrior II, Bifenthrin, countless generics (look for insecticide MOA 3A on the label). Many premixed products, including Endigo or Brigadier include a pyrethroid.
Plant bugs have developed resistance to pyrethroids, and these products eliminate beneficial insects, which may keep other pests in check later in the season. An early pyrethroid spray can often flare spider mites, aphids, and bollworms later in the year.
A good option for your first spray for plant bugs is Transform @ 2 oz/ac. Diamond @ 4-6 oz/ac can be included as well, where there are nymphs present. This product is an insect growth regulator and will not have activity for adult plant bugs. If timed correctly, it has been shown to increase the time before another plant bug spray is needed. Neonicotinoids (Centric, Admire) can also be effective early in the season, but need to be combined with other products to get good control as the year progresses. Be sure to check the label for restrictions on use patterns during bloom (e.g., application restrictions because of risk to bees and other insect pollinators).
This week’s corn earworm moth catches ranged from <1 to 13 per night in Virginia pheromone traps. Here is the Table. Also, Scott Reiter is operating two black light traps in Prince George, with nightly catches averaging 2 moths (Petersburg) and 0.7 moths (Disputanta).
Captures of AGB adults in our Sussex County, VA black light trap dropped sharply in July and we shut down the trap. Here is the graph for the entire season:
Thanks to the folks at this location for allowing us to conduct a second year of monitoring this insect!
