Stinkbugs infested nearly half of the 2.9 million acres of soybeans in Arkansas in 2001, causing farmers to shell out a considerable amount of money for insecticides and applications.
“It was a lot of expense for $4 beans,” says Jeremy Greene, Extension entomologist with the University of Arkansas Division of Agriculture. He's stationed at the Southeast Research and Extension Center at Monticello, Ark.
He says the costs didn't take into account losses from green bean syndrome, a disease believed to be associated with stinkbugs. The disease caused some fields to fail in 2000 and 2001.
But, on average, stinkbugs weren't nearly as bad a problem in 2002. Greene thinks he may know part of the reason.
“Stinkbugs have a lot of alternate wild host plants. I suspect that with frequent rains early in the season, many of those plants remained greener and more lush in 2002 than the year before.”
Greene says 2001 was drier, and stinkbugs apparently deserted their normal wild host plants and “jumped” into the more succulent, irrigated soybeans.
Stinkbugs have become a problem in recent years because of natural cycles probably related to factors such as climate and populations of natural enemies, says Greene. He says the success of the boll weevil eradication may also have an impact on stinkbug numbers.
To address the continuing problems that stinkbugs cause, the university has two research projects under way. The Arkansas Soybean Promotion Board is sponsoring the projects.
In one project, Rose Gergerich and Cliff Coker, Division of Agriculture plant pathologists, are trying to establish the cause of green bean syndrome. So far, they haven't been able to associate any known viruses in southeast Arkansas with green bean syndrome.
In another project, Greene is working with Seth Young and Gus Lorenz, Division of Agriculture entomologists, on stinkbug treatment levels.
“We're addressing thresholds and verifying that our established levels are correct,” Greene says. “We're looking at when you can terminate insecticide use for stinkbugs in soybeans based on plant physiology.”
Another objective of the board-sponsored research is to examine new and existing products to evaluate their effectiveness.
“It's too early for results on the threshold work and the termination of insecticide work, but we've got quite a bit of data on efficacy of products,” says Greene. “Some of the existing products labeled for use in beans are still effective, and some newer products are promising.
“Methyl parathion is still really good. Some of the pyrethroids labeled for use in beans that look good are Karate, Asana and Fury. Use of Fury and Orthene in Arkansas soybeans is new for 2002.”
Dwayne Beaty, who coordinates the Soybean Research Verification Program, notes that farmers in 2001 who raised late Group III variety beans didn't have to spray for stinkbugs.
“They were able to outrun them. We saw the same thing in 2002 in southwest Arkansas. We didn't have to treat the Group IIIs. Stinkbugs were a little slower coming into the fields, and the IIIs were past maturity when levels started to building.”
Lamar James is an Extension communications specialist with the University of Arkansas.