Asiatic garden beetle (AGB) captures in our Sussex, VA black light trap spiked the first week of June, totaling 1,281 adults over a 7-day span. Some severe AGB foliar injury to seedling cotton was reported near Wakefield (image below). We dug up cotton plants and marestail in AGB hotspots, finding adults under each, but we do not have evidence that they feed on cotton roots. For more information, please see our Virginia Cooperative Extension publication, “Asiatic Garden Beetle in Cotton”
On Monday, May 26 the Tidewater AREC entomology team collected tobacco thrips from cotton throughout southeastern Virginia. These populations were sent to the University of Tennessee where they were tested in the lab for susceptibility to acephate, spinetoram (Hemi SC or Radiant), and dicrotophos (Bidrin). Across all the sites, the results were very consistent with;
75-79% mortality with acephate
100% mortality with spinetoram
47-50% mortality with dicrotophos
We would classify this as tobacco thrips having reduced susceptibility to acephate in southeastern Virginia. Acephate resistance was also previously confirmed in northeastern North Carolina, just across the state line. This year we have found a high proportion of flower thrips, which are harder to kill with acephate, and now have confirmed that acephate has reduced efficacy for tobacco thrips. If you still plan to make a foliar thrips application, or are making a second application after a previous acephate application, Hemi SC (spinetoram) should be considered for more effective control. See this previous blog post for more details on the importance of timing your foliar application for maximum economic return.
We’d like to thank Sebe Brown at the University of Tennesee and his team for running the lab tests and the Virginia Cotton Board for sponsoring this research.
It has been a cool and wet start to the cotton season in southeast Virginia, and growth is slow. With a slow start to the season some folks are considering a second foliar application for thrips management. There are a couple key things to consider…
The first thing to consider for effective thrips management is timing
The most consistent return on investment comes from a foliar application early in the first true leaf stage. An application at the second leaf stage sometimes pays off, which is more likely to be the case with our current growing conditions. If cotton reaches the three or four-leaf stage, foliar applications made for thrips rarely pay off.
The next consideration is what insecticide to chose.
One of the most commonly used products to control thrips with a foliar spray is acephate. There are two thing to consider when using acephate; 1) western flower thrips are not as susceptible to acephate as tobacco thrips, and 2) acephate resistance has been documented in tobacco thrips in northeastern North Carolina, just across the state line from us in southeastern Virginia.
Populations of western flower thrips have been high so far in southeastern Virginia.
In several trials at the Tidewater AREC in Suffolk, we found around 80% western flower thrips in a foliar insecticide trial. Additionally, collections made from grower fields throughout Suffolk and Southampton counties on May 23 averaged 73% western flower thrips. While most fields did have a majority of western flower thrips, it is important to note that it varies between fields even across a relatively small area, and some sampled fields had a larger proportion of tobacco thrips. A table of thrips collections from May 23 can be found below. Each row represents a sample of five cotton plants in a field in Suffolk or Southhampton county.
| Field | Tobacco thrips | Western flower thrips | % Western flower thrips |
| #1 | 2 | 6 | 75% |
| #2 | 2 | 13 | 86% |
| #3 | 1 | 4 | 80% |
| #4 | 4 | 23 | 85% |
| #5 | 11 | 3 | 21% |
| #6 | 1 | 9 | 90% |
| #7 | 1 | 8 | 88% |
| #8 | 4 | 4 | 50% |
In the foliar insecticide test at the TAREC, acephate (at 3 oz/ac) did not provide better control than not treating with these high populations of flower thrips. Hemi SC (spinetoram), provided good thrips control at both the 2.5 and 3 oz rates. Hemi SC is the same active ingredient found in Radiant and is available for use in Virginia and the Carolinas this year for thrips suppression. It is important to mix Hemi SC with a non-ionic surfactant or with an herbicide which already contains a surfactant, to get good thrips control.
If you are using acephate, you should carefully monitor the performance of the application in your field. If you are not satisfied with the performance of an acephate application, the cotton growth stage and the growing conditions at that time should be assessed before considering a second application. If a second application is made, Hemi SC should be considered for more effective control and to rotate the insecticide mode of action. Bidrin should not be used for a second application after acephate, as these two insecticides are the same mode of action.
Both acephate and spinetoram can be washed away by rain up to 8 hours after application (or possibly longer), but acephate is slightly less susceptible to being washed away when comparing the two. However, some protection from a foliar application is better than none under current conditions, which are expected to extend through this weekend.
As a reminder, if you are planting Thryvon cotton, it provides excellent thrips control and does not need a foliar application. If you have any thrips questions contact Tim Bryant (757-621-8804, btim2@vt.edu), field crop entomologist at the TAREC in Suffolk, VA.
Corn earworm (= bollworm) moth catches were exceptionally high this week, continuing to climb in Dinwiddie, Prince George, and Suffolk, VA black light traps. The average number captured per night was 38 in Greensville, 79 in North Dinwiddie, 72 in Prince George/Disputanta, and 124 in Suffolk. Thanks to Sara Rutherford, Scott Reiter, and the Tidewater AREC entomology crew for their reports. Here is the Table.
Location: Virginia Tech Tidewater AREC Research Farm (1045 Hare Road, Suffolk, VA). This event is free and open to the public. Registration begins at 7:30 am with tours starting at 8:00 am. Lunch will be provided, followed by a Peanut Agronomy Tour in the afternoon. Here is the Tour Program.
If you are a person with a disability and desire any assistive devices, services, or other accommodations to participate in this activity, please contact Matthew Chappell, Tidewater AREC Director at (757) 807-6537/TDD 800-828-1120 during business hours of 8:00 a.m. to 4:30 p.m. to discuss accommodations five days prior to the event.
Corn earworm (= bollworm) moth catches increased greatly this week in southeastern Virginia black light traps. The average number captured per night was 50 in Greensville, 42 in North Dinwiddie, 39 in Prince George/Disputanta, and 67 in Suffolk. Thanks to Sara Rutherford, Scott Reiter, and the Tidewater AREC entomology crew for their reports. Here is the Table.
We have evaluated over 250 moths in our 2024 vial tests, with 57% surviving the 24-hour exposure to the pyrethroid insecticide, cypermethrin, at 5 micrograms per vial.
Corn earworm (= bollworm) moth catches really started to increase this week in southeastern Virginia black light traps. The average number captured per night this week was 4 in Greensville, 11 in North Dinwiddie/Petersburg, 18 in Prince George/Disputanta, and 30 in Suffolk. Thanks to Sara Rutherford, Scott Reiter, and the Tidewater AREC entomology crew for their reports. Here is the Table
We have evaluated over 150 moths in our 2024 vial tests, with 61% surviving a 24-hour exposure to the pyrethroid insecticide, cypermethrin, at 5 micrograms per vial. Even though cypermethrin is no longer widely used, survival rates this high suggest we need to watch for some pyrethroid control failures, and to consider alternative chemistries when an insecticide is needed.
Black light trap catches of AGB per 3 to 4 nights in Sussex County, Virginia were 500 on June 7 and 487 on June 10, 2024. Producers have reported seeing adult AGB just by kicking over the top inch or so of soil in infested areas. I heard of 5 acres of cotton in Suffolk with very heavy AGB defoliation, but there are more reports where injury is not as severe. I look forward to learning when our AGB population will finally decline.
Captures of Asiatic garden beetle (AGB) in our black light trap climbed this past week, with 300 adults caught between May 31 and June 3, 2024. We do not know if we have reached peak emergence yet for this sporadic pest. Johnny Parker (Commonwealth Gin) reported three Virginia seedling cotton fields with AGB injury so far this season, with defoliated areas reaching 2 acres. Check for these insects under weeds such as pigweed, marestail, or volunteer soybean–focus especially on sandy soils. You may see round adult emergence holes in the ground. Or, a visit to the field at night (when adult AGB are active) may confirm the problem.
In a June 4, 2024 Pest Alert, Dr. Dominic Reisig and Dr. Guy Collins (North Carolina State University) provide AGB scouting and management information which is also applicable for Virginia cotton growers. Contact insecticides would need to be applied during peak emergence, and at night.
In 2023 there were multiple, scattered reports of severe defoliation and/or death to cotton seedlings caused by Asiatic garden beetle (AGB) in Virginia and northeast North Carolina. Infested cotton areas varied in size, with some reaching 10 acres. AGB feed on roots (as grubs) and foliage (as adults) of many different host plants. The adults hide in the soil during the day and feed at night. AGB prefer sandy soil over heavier soil. When we visited the infested cotton fields, we often found AGB in the soil below weeds (e.g., marestail) and volunteer soybean plants.
This April the Tidewater Agricultural Research and Extension Center’s entomology program began sampling field “hotspots” from the 2023 season using soil samples, pitfall traps, and a black light trap. We found AGB grubs in soil samples from fields in Wakefield and Sussex County, VA, but did not find them in a northeast North Carolina field infested last year. AGB grubs can be differentiated from other white grubs by their “puffy cheeks.”
The black light trap is being operated in Sussex County, VA; it had a peak of 114 AGB adults (total per 3 nights) on May 9, 2024, followed by a sharp decline in captures. Other states have reported a single generation of AGB per season, but we plan to keep monitoring for several more weeks. We are still finding grubs and pupae in our soil samples. Pitfall traps placed in the field, designed to capture crawling adults (not flying due to cool temperatures), have not captured any AGB so far.
Cotton infestations and seedling injury from 2023 may have been due in part to cool May temperatures, keeping AGB adults on the ground, feeding in the cotton fields where they emerged; the cooler weather also limited cotton seedling growth.
We’ll provide further updates as we learn more. If you suspect an AGB problem in your seedling cotton, please feel free to reach out to me, or contact your county Extension Agent.
Acknowledgements: We are grateful for the financial support provided by Cotton Incorporated and the Virginia State Cotton Support Committee, and for the assistance provided by local cotton growers.
