According to a report released by the Soybean Gall Midge (SGM) Alert Network in August, this new pest is continuing its gradual spread from the western border of Iowa to central counties. Erin Hodgson, plant pathology, entomology and microbiology, Iowa State University, and her research team carefully scouted for midges in July and August to document the distribution and rate of spread in the state. New counties reporting the presence of SGM include Humboldt, Kossuth, Palo Alto, Pocahontas, Polk, Ringgold, Warren and Webster. There are 42 counties in Iowa now affected. In all, 15 new counties were identified in Iowa, South Dakota and Nebraska in 2022.

Erin Hodgson notes, “The new county detections this year had very low levels of soybean gall midge larvae. Farmers probably wouldn’t even know they had them in the field. We were looking at a lot of plants just to find a few infested ones. Our goal is to track the progression of this soybean pest to new areas. We expect new county detections will continue slowly each growing season.”

There are several collaborative research projects going on at Iowa State University to better understand how to manage the gall midge, which is a fly. The topics of biggest interest include cultural management tactics, like date of planting and vegetation management, mechanical suppression with tillage, insecticide efficacy evaluations, and host plant resistance. With other midges in field crops, host plant resistance has been the most effective tool. This is partly due to larvae being hard to access with insecticides and the long duration period of adult activity.

Unfortunately, many of the strategies that have been tried so far have not been effective in suppressing SGM. There is hope for breeding soybean varieties that are tolerant of larval feeding, but it will take a few years to identify the genes responsible for resistance. Experts recommend monitoring for larvae during July and August, especially in soybean fields that have a border with a field where soybean was planted the previous year.

More information can be found at https://soybeangallmidge.org. If you are interested in real-time updates on SGM activity and distribution in 2023, join the Soybean Gall Midge Alert Network or the Iowa Pest Alert Network.