We’ve made it through this growing season with little to no insect activity, so it makes sense that we would run into some issues in late August. Brad Easterling (EA-IPM, Glassock, Reagan, and Upton counties) is reporting above threshold levels of bollworms in Bt cotton fields near Garden City. While we don’t yet know the cause of this, entomologists and IPM agents around the state are working to determine the nature of the problem we are dealing with.
Locally, trap catches in Crosby county (Fig. 1) for adult bollworm moths indicated a large flight around the second week of August, but numbers have been decreasing since. This is not to say that we should be complacent in our scouting of cotton; sorghum and cotton (especially lush cotton, Bt or not) should be scouted regularly.
|Figure 1. Trap catches of adult fall army worms (black bars) and bollworms (blue bars) in Crosbyton, TX.|
Dr. Suhas Vyavhare, Cotton Entomologist with Texas A&M Agrilife Extension, says that when scouting for bollworm larvae you should do whole plant inspections, including squares, white and pink blooms, bloom tags, and bolls. At least 100 randomly selected plants covering major areas in the field should be inspected. When plants are 3 nodes above white flower (NAWF) or less, they are typically safe from bollworm injury.
Check out this video on how to scout for bollworms in cotton from Blayne Reed (EA-IPM, Hale, Swisher, and Floyd counties).
If you do see any unexpected feeding damage or have any questions about bollworms, feel free to give me a call!