By now we should know to expect surprises, particularly when insects are involved.
West Tennesseans expecting lighter pest pressure this past season, thanks to the boll weevil eradication program and varieties genetically engineered to resist insects, found themselves facing a sometimes-overwhelming stinkbug invasion.
Soybeans were particularly hard-hit in some areas. “We always see some stinkbugs in beans but haven't had this kind of problem before,” says Gene Outlaw, Bells, Tenn. “We had parts of fields that should be making 40 bushels cutting in the 20s.”
Tim Roberts, Crockett Co., Tenn., Extension agent, found himself checking more soybean fields than in the previous six years he worked the area. “It was all due to stinkbugs. They were not in every field but we could find them in large amounts. One week a field would be clean and the next week it would be wrapped up in stinkbugs,” he says.
Stinkbugs also clipped cotton yields, says Woody Woodson, Helena Chemical sales representative, Alamo, Tenn. “There were bolls that didn't open because of them. A couple of fields where the farmer didn't fight them yielded 300 pounds. Stinkbug was the biggest problem this year, by far,” he says.
Jimmy Hargett, who grows cotton near Alamo, Tenn., says just about every farm faced more stinkbug pressure than usual. “It's hard to say just how serious it was. There wasn't a lot of boll weevil spraying here this year. I think malathion does a good job on them. There was hardly any worm spraying this year, either, though there was some spraying for thrips. Less spraying could have been the reason stinkbugs were worse than normal,” Hargett says.
That made field scouting more essential than ever before. “I did a lot of scouting on mine and sprayed for thrips and stinkbugs. I didn't have a whole lot of problems and maybe that's why,” Hargett says.
Pyrethroids do a good job on stinkbugs, Woodson says. “We're going to have to scout for them. In cotton, the method is to use drop cloths in 25 spots in the field. In soybeans, sweep nets are the best way. When you scout, you'll find both matures and immatures. The matures will cause the damage in soybeans until the beans get golden, so you need to try to control them. There's going to be a lot more scouting for stinkbugs after this,” he says.
“Scouting is absolutely the best thing to do, to know what's out there,” Roberts says. “When you have a big acreage, that can be hard to do. If you don't have time to do it right, you need to hire it out. Scouting is the one thing you can do to maximize insecticides. If you know what's out there, you can treat it. And you're not wasting money spraying for it if it's not out there.”
Stinkbugs likely exploded through the area because of reduced boll weevil and worm sprays, Roberts says.
“The boll weevil was practically extinct here this season because of a combination of the eradication program and cold winter weather. When we're not doing much spraying, the stinkbug population goes up exponentially,” Roberts says.
“The insect spectrum has changed. We knew when the boll weevil eradication program started, minor pests would come to the forefront. That's what happened.”
After cotton hardened off, stinkbugs migrated to soybeans, Roberts says. “They were looking for something else, so they began to feed on pods. They have a piercing part that sucks the nutrients out of the bean. That makes the bean shriveled. They can still damage the bean until it's drying down,” he says.
Controlling stinkbugs in soybeans will require refining management, as well. “In this area we never sprayed beans for insects because we never had that real big problem,” Roberts says.
“But this coming season, we're going to be prepared. If you're going to plant it, whatever it is, you're just about going to have to protect it. You have to watch it. Stinkbugs are not hard to kill. You've just got to do it, that's all. If you don't, yields are going to be cut, soybeans are going to be small and there'll be low test weights. With prices being what they are, we can't afford that kind of hit,” Roberts says.
e-mail: [email protected].