Soybean gall midge upped its appearance by 10 days in Nebraska crops, and that could mean trouble for Missouri soybean growers who plant early.

First found in Missouri in 2019, the pest is in the state’s far northwestern counties of Atchison and Holt, University of Missouri Extension state entomologist Ivair Valmorbida says. And soybean gall midge can cause heavy damage:

The relatively new pest, reported six years ago, continues to expand its reach, moving into northeast Kansas last year. Missouri farmers along the northern border counties of Iowa, Nebraska and Kansas should be on guard and prepare for this growing season.

Valmorbida, and Justin McMechan, Nebraska Extension crop protection and cropping systems specialist, recommend these crop management strategies:

As soybean gall midge emerges in mid-June, it flies to a neighboring soybean field to lay eggs typically into cracks or fissures at the base of a plant in the V2 stage. Those eggs grow to larvae and feed off plants. Early-planted soybeans are at V2 about the same time as adult emergence.

Delayed planting moves the V2 stage beyond the emergence timeline, removing a soybean host plant for the pest. Adult soybean gall midge only survives for 15 days.

McMechan noted that seed treatments and foliar fungicides don’t necessarily work on soybean gall midge.

“They have some effect when you look at reductions in larval number and increasing rates,” he says, “but then when we get down to yield, we tend to lose those differences. We just don’t get consistent results.”

UNL researchers saw some success in reducing populations by hilling or mounding of soil around the plants. Hilling at the V2 stage had the lowest larvae per plant.

Greatest threat area on farm

If soybean gall midge is present, plant injury is likely along field edges near dense vegetation and waterways, and in fields directly adjacent to those planted in soybeans the previous year.

However, Valmorbida explains that larvae have also been found on alfalfa and sweet clover and may infect other legume crops.

He warns farmers to pay special attention to fields after a weather event.

“It is important to scout after a hailstorm, since hailstones create wounds on the stems,” Valmorbida says, “making openings for disease and pests to enter.”

Get out and scout

Valmorbida advises farmers to inspect fields after soybean plants reach the V2 growth stage and look for dark discoloration at the base of the stem.

“Peel back blackened tissue in discolored areas near the base of the soybean stem to look for white or orange larvae,” he adds. “Heavily infested plants will wilt and die.”

Life cycle of soybean gall midge

Consult your local Extension agronomist if you suspect soybean gall midge in your crops.

Sign up for free soybean gall alerts from the Soybean Gall Midge Alert Network or MU Extension’s free Integrated Pest Management Pest Monitoring Network.