Soybean gall midge
Soybean farmers are encouraged to look for Soybean Gall Midge, or orange gall midge, in their soybeans this growing season. This new pest to Missouri was first documented in Nebraska in 2011 and was found in Atchison County, Missouri in 2019. Maps from surrounding states indicate that it has likely spread throughout Northwest Missouri.
Soybean gall midge overwinters as larvae in the first few inches of soil. Adults emerge in early spring and lay eggs at the base of soybean plants. Once the eggs hatch, the maggot-like larvae burrow into the soybean and feed on the base of the stems. Eventually, the plants will wilt or die, with most damage occurring on the field edges. Limited research results have shown yield losses of up to 20% on the outer 400 feet of a heavily infested field, with complete yield loss on the outer edges.
To scout for orange gall midge, inspect field edges for wilted or stunted soybean plants. Inspect the base of the stems, looking for dark discolorations at the ground.
The stems become brittle after infestation and will easily snap. Peeling back the epidermis will reveal the orange or cream-colored larvae. Soybean gall midge damage has been primarily confined to field edges, so scouting should focus on these areas. Infested fields will see yield loss from plant death, damage to the xylem and phloem, and increased risk of lodging due to reduced stem strength.
Because orange gall midge is a relatively new pest, there are not yet any research-based management recommendations. Foliar insecticides could be an option, although application timing and insecticide efficacy need to be studied. It’s also unclear if insecticides will be effective on larvae feeding inside soybean stems. Seed treatments have so far been ineffective, and varietal resistance has not yet been found.
Scouting for soybean gall midge will help researchers track the spread of the pest, allowing them to better understand its preferred environment and determine appropriate control measures. If you find or suspect soybean gall midge to be present in your fields, contact your local University of Missouri Extension office or call Andy Luke, at 660-425-6434.