Cotton insects changing with times Don't worry about the insect. They'll figure out a way to adapt to any controls we can come up with. It's hard for cotton growers not to become at least a little cynical as they adopt new insecticides and insect resistant cotton only to see some insects developing resistance and new insects moving into cotton fields.
"It's frustrating to me and my fellow consultants," says Stan Winslow, referring to late season attacks of plant bugs and green and brown stinkbugs this past season. "I am very confident we will be dealing with these insects again next year. We're going to have to adjust our scouting procedure and spend more time in the fields, especially at the end of the season."
North Carolina State University Entomologist John VanDuyn says stinkbugs and lygus plant bugs have historically been a problem in cotton fields farther south and then mostly early in the growing season in pre-bloom cotton. While some of the insects have been showing up early in North Carolina, the most damaging infestations come in July and August, particularly in Bollgard fields. The plant bugs and stinkbugs attack down in the plant canopy early in the season and show up in the upper parts of the plants as the season progresses.
Scouts and consultants are having to learn how to find the pests, how to establish thresholds and even when it is safe to stop spraying.
"Lygus bugs get started in potatoes or weeds or even in corn later in the season," VanDuyn says. "When they reproduce the nymphs go for cotton squares and blast the squares. We wind up with missing squares. We wound up this year with deformed bolls, hard locked cotton and bolls falling off.
"Stink bugs are powerful flyers. They move from crop to crop and eventually into cotton fields. They puncture bolls so they can feed on the seed. Once they have damaged a seed, that seed produces immature fibers or no fibers at all. Early this year they injured bolls and those bolls ended up rotting and falling off the plants. Then they came back in July and August and damaged bolls in the top of some plants."
Both Winslow and VanDuyn say that brown stink bugs are the most difficult to kill, but green stinkbugs do more damage. They encourage cotton growers to attend winter meetings to learn more about how to anticipate, scout for and control both lygus bugs and stink bugs in next year's crop.