Arkansas soybean growers beset by pesky weevil
By CHUCK BARTELS
LITTLE ROCK, Ark. (AP) — A cover crop used to keep soil from eroding has brought a couple of difficult pests to some farm fields in eastern Arkansas.
Growers south of Marvell planted Austrian winter field peas to sustain and enrich their soil over the colder months. What they didn’t expect was the springtime emergence of pea weevils, a pest that attacks soybean plants from top to bottom.
Also, brown stinkbugs are attracted by the winter field peas and they ripped through corn that was planted after the peas were plowed under, said Gus Lorenz, extension entomologist with the University of Arkansas System Division of Agriculture.
“All the (corn) damage from the stinkbug was only in that field where the cover crop was,” Lorenz said. An adjacent field that didn’t have the cover crop was untouched.
“So far,” Lorenz said.
Some corn plots suffered 100 percent yield loss because of the stinkbugs, he said.
Getting rid of the pea weevils in soybeans can be expensive.
“You’ve got the maggots (immature weevils) feeding on the roots and nitrogen nodules and the adults feeding on the top of the plant,” Lorenz said.
A pesticide application will take care of the weevils feeding on the top of the soybean plant. But subsequent applications are necessary when the immature weevils leave the soil as adults and start chomping the leaves.
Lorenz said growers can face “severe economic loss” from the stinkbugs.
“With the pea weevil, trying to determine economic loss associated with it is kind of hard,” he said.
Even if there is no yield loss, farmers still have to pay to have their fields repeatedly sprayed.
Robert Goodson, Phillips County extension agent for the division, said the pea weevils leave a unique mark on soybean plants as they feed on the outside of the leaves.
“It looks like you took some pinking shears and went around the edge of the leaf,” Goodson said in a news release. “It’s a very distinct feeding pattern.”
“As many as you see on the leaf, if you dig down into the cover crop residue, there’s a ton more of them,” he said.
Lorenz said he doesn’t believe there is much of a chance that the pea weevils will spread beyond the fields where the winter field peas were planted.
He said the growers planted the cover crops with the intention of improving their soil.
“Anything that adds organic matter to the soil, that adds nitrogen, is beneficial,” Lorenz said. “I think they went into it thinking it was going to be a very positive thing.”
A point to be learned is that “not everything about cover crops is positive,” Lorenz said.