In late June 2018, entomologists in Nebraska, Iowa, South Dakota, and Minnesota began receiving reports of soybean fields with visible signs of dead or dying plants that were found to be associated with soybean gall midge. By the fall of 2019, an additional 30 counties were identified as infested in those states, and an infestation was reported in northwest Missouri. To document clientele need for research on this new pest, a research petition was developed to determine the threat of soybean gall midge and the need for research on this new species. In Nebraska, a total of 367 signatures have been obtained since the petition was developed on December 18th, 2018 to Feb 20th, 2019. The presence and injury of soybean gall midge was most significant in fields adjacent to crop that was soybean the previous year. In addition, dense vegetation (grasses and shrubs) between these two fields has been observed to increase the infestation potential of soybean gall midge. In 2019, emergence cages were used to track overwintering soybean gall midge adults from 27 sites across four states as part of an emergence NCSRP project. On June 14th the first overwintering adults were captured in east-central Nebraska. Within 11 days of first emergence, soybean plants began showing visible signs of infestation. The duration of overwintering adult emergence varied significantly between sites ranging from 10-23 days in Nebraska with an average of 16 days across all sites. At ENREC near Mead, NE, a preliminary experiment on planting dates of soybean relative to adult emergence was conducted with one year of support from the North Central IPM Center. Results showed that approximately 50% of plants were infested with May 1st and May 14th planting date whereas only 3% of plants were infested when planted on May 31st. This proposed 3-year project would continue to evaluate planting date relative to adult emergence and expand this effort to include the use of an insecticide seed treatment. In addition, growers would be identified to evaluate and compare the results of planting dates on their farm relative to soybean gall midge emergence. Results from this study would provide farmers with an understanding of risk for overwintering soybean gall midge infestation with different planting dates as well as the potential for seed treatments to mitigate early season infestations.

The first objective will be to evaluate soybean gall midge infestation and injury of soybean planted at four different planting dates with and without an insecticide seed treatment.

For the second portion of the project, farmer fields will be monitored for adult emergence data as part of an ongoing NCSRP and NSB project. To add to this project, adjacent farmer field’s will be evaluated for the planting date and the use of seed treatments relative to adult emergence at these sites.

Resulting data from this project will be presented at a number of Nebraska Extension efforts such as Soybean Management Field Days (approx. 400 attendees), Nebraska Crop Management Conference (approx. 300 attendees), Midwest Crop Production Clinic (50 attendees), Crop Production Clinics (1,400 attendees), and Nebraska Soybean Expo (300 attendees). Updates on research progress will be presented through Blackboard Connect Alert System, Twitter, Market Journal, grower listserves, Market Journal interviews, and UNL Cropwatch articles. We would expect that at least two peer reviewed publications will result from this work.

Updated May 25, 2023:

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Data from the 2022 growing season was lost due to a hail storm on June 7th. Our previous years data indicated there may be planting dates that are highly susceptible to injury from soybean gall midge. Growers looking to potentially reduce soybean gall midge populations for future years may want to consider delayed planting if they have significant historical injury and pressure from soybean gall midge. Seed treatment impacts were limited to soybean plantings from April 22nd to May 12th. Our results indicate that planting date alone is more effective but more research is needed.

Planting date has always been an important consideration for soybean farmers. Knowledge of the impact on this tactic with significant soybean gall midge pressure would allow farmers to potentially prioritize fields to reduce risk of soybean gall midge injury. Studies of its interaction with seed treatments would provide an evaluation of the value of this tactic in combination with planting date to mitigate losses and maintain production of soybean.