Soybean aphids have been reported at low levels statewide and growers should be aware, says Bruce Potter, a specialist in integrated pest management with the University of Minnesota Extension Service.

ìPopulations right now are fairly low,î said Potter, with the Uís Southwest Research and Outreach Center in Lamberton, Minn. ìItís not time to spray yet, but itís time to start thinking about scouting your fields and keeping an eye on developing populations.î

Researchers from the Uís Northwest Research and Outreach Center in Crookston, Minn., identified soybean aphids at the end of May. It marked the earliest date soybean aphids had been recorded in northern Minnesota fields.

According to Potter, soybean aphids tend to show up in fields near lakes and streams first. He says itís also a good idea to check in smaller fields and fields surrounded by buckthorn. Aphid eggs often survive on local buckthorn until they hatch and develop wingbuds needed for migration.

ìLook for ants and lady beetles, too, since they will often be around little aphid colonies,î Potter said.

The bottom line, Potter says, is producers shouldnít make a rash decision to spray before completing a thorough assessment. After conducting a quick identification survey, go back and take more time. ìGo through the whole field, and donít just scout a hot spot,î he said.

The soybean aphid is an eastern Asian soybean pest that began invading the United States in the summer of 2000. It was first detected in the Midwest. Results from Minnesota Department of Agriculture pest surveys since 2002 illustrate it can infest soybeans virtually anywhere they are grown in the state.

Yield loss in early infested fields is primarily caused by aphids stunting plants. This can result in fewer nodes and pods.

Soybean aphids are small yellowish aphids with dark, upright structures on the back of the abdomen that resemble tailpipes. The aphid is difficult to see with the naked eye, and a hand lens is valuable in making identifications.

For more information on soybean aphids, visit www.soybeans.umn.edu.