The UT Cotton Scout School is scheduled for Wednesday, May 21st, at the West Tennessee Research and Education Center (605 Airways Blvd, Jackson). There is no fee, and preregistration is not required. Registration begins at 8:00 AM with the program starting at 8:30. Pesticide points in categories 1, 4, 10 and 12 will be offered and a BBQ lunch will be provided. Content will include classroom and hands-on training with an optional go-to-the-field session after lunch. Topics covered will include cotton development and identification and symptoms of insect pests, plant diseases, and weeds.
I’ve gotten a few calls on fall armyworms (FAW) infesting cover crop wheat and production wheat. FAW, in large enough numbers, will defoliate a wheat field if left uncontrolled and UT’s FAW threshold is four worms per square foot. To date, pyrethroids have been providing satisfactory control of FAW in soybeans and pastures and the same can be assumed for wheat. Pyrethroids are the most economic option but also provide the shortest residual (3-5 days). Other options include Vantacor, Besiege and Radiant/Blackhawk. Insecticide seed treatments for Hessian Fly and/or aphids won’t control FAW and if numbers exceed threshold a foliar spray may be required. Another option is to delay wheat planting until after October 15th (Hessian Fly Free Date) as infestations of fall armyworm almost always occur in early planted wheat, especially for wheat planted in September.
Bollworm egg lay across West TN is rapidly increasing. Our trap catches across the survey area are steadily increasing and I’ve started receiving several calls about large numbers of eggs . Fortunately, the vast majority of our cotton is Widestrike 3 (WS3) or Bollgard 3 (BG3). To date, I’ve had no reports of slippage through any three gene cotton in Tennessee. Going forward, our threshold for foliar applications targeting bollworms occurs when a combination of square and boll sampling shows 6 percent or more injury (e.g., 3 percent square injury and 3 percent boll injury, 4 percent square injury and 2 percent boll injury, etc.) and/or 4 or more larvae are present per 100 plants. Treatments based on egg lay is not recommended in 3 gene cottons. My colleague at Mississippi State, Dr. Tyler Towles, summarized our regional data (Fig. 1) demonstrating no economic benefit to making a diamide application to 3 gene cottons. Unless you’re at threshold, save the money on the diamide spray in 3 gene cotton.
Fig 1. Diamide Sprays by Bt Technology
One final note, as we are nearing the end of the 2024 growing season below are insect termination timings based on DD60s.
