Just like cotton farmers, cotton insects live in a brand new world these days. Unlike many farmers, though, a lot of the insects seem to love it. The bugs are finding ways to thrive, thanks to more diverse cropping patterns in traditional cotton- producing areas and possibly some management changes, as well.
With today's transgenic varieties becoming commonplace, bollworms and budworms no longer pose much of a problem. Now plant bugs, stink bugs and spider mites cause more challenges for most farmers.
"There are three reasons the pest status changed. First, the use of transgenic varieties. Second, the boll weevil eradication program fired up the sucking bug complex. And there are alternate hosts for the sucking bugs. Cotton is attractive for these pests, so we see very high numbers of them coming into cotton from other crops,” explains Gus Lorenz, a University of Arkansas Extension entomologist.
"A lot are still sampling fields the way they did when worms were the problem. If the sucking bug complex is the No. 1 problem, we have to alter sampling methods and take action,” Lorenz says.
Though they haven't hit the top of the list of insect problems, spider mites have surprised many cotton farmers in recent years. Increased corn acreage in cotton-growing areas has probably pushed up mite numbers.
"They've been plaguing us for four years in the mid-South. We've had a lot of problems all the way from emergence to harvest, at some level. I can tell you they're real. They've been bad, driving a lot of our guys crazy,” says Angus Catchot, a Mississippi State University (MSU) Extension entomologist.
Mite control gets costly. Jeff Gore, an MSU entomologist working at the Delta Research and Education Center in Stoneville, Miss., says early season control costs $15 per acre to $30 per acre and late-season application costs $6 per acre to $15 per acre.
"Mite products only kill mites. With late-season mites, there's a big question. You've got mites spotting across fields—do you need to treat? That's a big, big decision, moneywise. You've got to stay on top of them. It takes green leaves to fill those bolls out,” Catchot says.
Timeliness is key when dealing with spider mites. You almost have to anticipate when populations will explode.
"I can't stress timeliness enough. When you go to a field and can see a bad problem, you're late out there. You want to keep hot spots to a minimum and come in and get that treatment on,” Catchot says.
"Mites like stressed, weak plants. They're opportunistic. Healthy plants that have been irrigated do better at holding off mites,” he says.
- March 2009