The Alabama Cooperative Extension System’s economic threshold for kudzu bugs in soybeans this year, he says, call for treating prior to first bloom when there is an average of five kudzu bugs per plant for the entire field.

“After first bloom through R6, apply an insecticide when a sweep-net sampling catches 10 adults per sweep or one nymph per sweep. When using a sweep net, a sweep is defined as one sweep across two rows using a 15-inch diameter sweep net.,” says Reed. “If immature kudzu bugs are easily and repeatedly found on petioles and main stems during visual inspections of the canopy, treatment is likely warranted.”

He advises that growers should not limit all sampling to border rows where populations build initially.

“Border treatments in some cases have slowed the movement of adults across fields. If immature kudzu bugs are easily and repeatedly found on petioles and main stems during visual inspections of the canopy, treatment is likely warranted,” he says.

Retreatment may be necessary when a treatment is applied before migration into soybeans stops, says Reed, and growers should be aware that spraying for kudzu bugs will significantly reduce beneficial insects, which could result in economic infestations of caterpillars.

This threshold, he says, is based on one year’s experience and will be adjusted as more research is conducted and experience is accrued. “Due to the tendency of this pest to congregate on the field borders, initially it is important that growers use an average population estimate for whole fields before making a whole-field insecticide application.”