Soybean gall midge not damaging Illinois soybeans - yet

In 2018, soybean gall midge (Figure 1ab) emerged as a new species causing significant injury (Figure 1c) and yield loss to soybean in Nebraska, Iowa, South Dakota and Minnesota. (Photo provided by University of Nebraska)

It’s not here yet, but there’s a new soybean pest approaching on the distant western horizon. University of Illinois entomologists Joseph Spencer and Kelly Estes were part of a project to survey for the soybean gall midge (SGM) in Illinois during the 2020 growing season.

Last year, infestations in 19 additional counties were documented, bringing the total number of infested counties to 114 across South Dakota, Nebraska, Minnesota, Iowa, and Missouri. The nearest infestation to an Illinois border is more than 140 miles away in central Iowa.

Last summer, Spencer and Estes sampled 208 soybean fields in 45 Illinois counties. No evidence of SGM activity was detected anywhere in Illinois. Plans include monitory for SGM this year and beyond.

“We encourage Illinois producers to photograph and report any suspected SGM damage observed in Illinois soybean fields during 2021,” said Estes.

Economic damage occurs when the bright orange larvae of the midge, a type of small fly, feed on vascular tissues at the base of soybean plants. Most heavy damage (complete yield loss) is confined to areas within 100 feet of field edges, with 20% yield loss possible within 200 to 400 feet of the field edges.

Plants that are not killed by an infestation are likely to experience reduced yield. Additional losses are possible due to lodging of weakened plants.

SGM overwinters as a larva in the soil of soybean fields. They pupate and emerge as adults in June and July. Subsequent infestations are most likely on the edges of soybean fields that are adjacent to soybean fields that were infested during the previous year.

Adults are believed to lay eggs at the base of soybean plants. Early indications of an infestation may include discoloration of plant stems near the soil interface. More advanced infestations may manifest as wilting or dead plants. There are multiple generations each year.

University of Nebraska data suggest no single approach exists to manage SGM. Click here for more information about management strategies.