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Soybean gall midge a difficult pest to manage

An extension entomologist says soybean gall midge is a difficult crop pest to manage.

Bob Koch with the University of Minnesota says the insect is still new so threshold levels for treatment have not been established.

“It seems like the seed-applied insecticides aren’t providing much control, based on research from my colleagues in Iowa (and) Nebraska. Foliar-applied insecticides, the insecticide sprays, aren’t really doing all that much. And that may be due to the fact that these larvae are protected inside these stems.”

Gall midge larvae feed on the base and lower stem of soybean plants, hindering the movement of water and nutrients.

Koch tells Brownfield adult gall midge are small flies that should be easy to control.

“But the complicating factor is we’ve got these adult flies coming out over extended periods of time in multiple generations over the years. So you wouldn’t be able to target them with just a single spray.”

According to the Soybean Gall Midge Alert Network, the pest has been identified in several Midwestern states this summer including two new counties in Iowa and three in Minnesota.  The Network says there’s also been a significant increase in adult emergence and plant injury in eastern Nebraska.