Farmers can add soybean aphids to the growing list of crop threats that are becoming more difficult to control.
The aphids, which were first spotted in the United States in 2000, are demonstrating resistance to some of the most common insecticides used to control them, Erin Hodgson, Iowa State University Extension entomologist, said last week. The discovery will require more management to protect yields and extend the longevity of currently available insecticides, she said.
"Farmers know about herbicide groups and the need to rotate them," she said. "We’re going to have to become aware of that for insecticides, too."
Hodgson was alerted last summer to a soybean field in northwest Iowa that was sprayed twice with a foliar pyrethroid insecticide but still had high aphid populations. She took the...