Stink bugs are stinking it up for southern growers. But the good news is that there are sufficient tools to “soften their odor” for soybean and corn production.
Dow Brantley's family has farmed in England, AR, just southeast of Little Rock, for decades. Cotton has been their main crop, but soybeans, corn and rice are also leaders in a strong rotation.
When soybean and corn budgets are written, there's always space for stink bug control. And there had better be, says Gus Lorenz, University of Arkansas Extension entomologist, citing a growing problem with stink bugs in the Midsouth region.
For Brantley, corn has been in the rotation about six years, while soybeans have been grown off and on for years. “Corn is still new for us,” says Brantley. “Insects are usually not a major problem and we don't spray much, except for stink bugs. They hit corn early or from tasseling on and there's no help from the Bt gene.”
Some growers spray a preventive application. “But we'd rather spray when the bugs reach threshold levels,” says Brantley.
The economic threshold for stink bugs on corn is one bug per 20 row-feet, says Lorenz. “We often get a lot of activity in early planted corn,” he says. “They are hard to scout for and can easily be missed. If so, plants can be stunted or killed.
“There can be a lot of damage after the fact. Once you start figuring out there is damage, it's too late to do anything about it,” he says. “So growers are realizing they have to pay more attention to stink bugs in corn.”
WHEN SCOUTING SOYBEANS for stink bugs, the threshold in Arkansas for economic damage is one bug per row-foot, or nine bugs per 25 sweeps, says Lorenz. It can vary for neighboring states. Most damage is done when beans are in the R5-R6 growth stage.
Lorenz says early planted soybeans in 2009 saw stink bug levels already approaching the threshold in late June. “We had a lot of early stink bug activity, but we had the weapons to control them,” he says.
Most Arkansas stink bugs are green, with some brown, as well. Lorenz says a pyrethroid insecticide application normally controls them. “Pyrethroids like Karate, Mustang Max, Baythroid, Asana, Hero and Prolex work well. Growers can also use Orthene or methyl parathion which work well, too,” he says.
Farther south in Louisiana, the red-banded stink bug is the main culprit in soybeans. Jack Baldwin, Louisiana State University Extension entomology specialist, says the threshold is about 24 bugs per 100 sweeps.
“Orthene at a rate of 0.75-1 lb. active ingredient/acre has been the standard, but we have recently added some newer insecticides,” he says. “These include Endigo at 4-4.5 fluid oz./acre, and Brigade and Hero, both at 0.1 lb. active ingredient/acre. Baythroid, at .044 lb. active ingredient/acre, is still recommended for suppression.”
Lorenz advises growers not to spray for stink bugs unless the threshold is met because, “if the beneficials are killed, we can see a big problem with soybean loopers.”
He and Baldwin advise growers to consult with their local or regional entomologists to determine which stink bug treatment program is best for their areas.