By Erin Hodgson and Ashley Dean
This week, the first adult soybean gall midges (Photo 1) were collected in Iowa and Minnesota. Thanks to Lauren Schwarck (Corteva Agriscience) for monitoring several emergence traps this year. The positive detections were located in Buena Vista County, an area with persistent soybean gall midge populations since at least 2017.
Photo 1. Adult soybean gall midge.
The adults have been steadily emerging from Nebraska for three weeks. Approximately two weeks after first emergence, plant injury was noted at some Nebraska collection sites. Based on their emergence timing, we would expect to see feeding injury to start appearing near previously infested fields next week.
Soybean gall midge is a new soybean pest that is only known to occur in 114 counties in 5 states (Figure 1): Nebraska, Iowa, Minnesota, South Dakota, and Missouri. Currently, 31 counties in western Iowa have positive detections as of 2020. The larvae (maggots) of gall midges feed inside the stem near the base of the soil. Eventually, infested plants may become brittle and break off at the site of feeding. Entire plants may die as a result of feeding, causing significant yield losses for a field. Typically, infestations begin at the field edge, where farmers will notice wilted or dead plants, then advance toward the interior.
Figure 1. Locations in Nebraska, Iowa, Minnesota, South Dakota, and Missouri where soybean gall midge has been identified.
Iowa has several trapping locations this year and supports a regional trapping network in four states. We will continue to provide updates on adult emergence throughout the summer. To stay updated on state and regional midge activity, we encourage you to subscribe to the Alert Network: https://soybeangallmidge.org/sign-up-for-network-updates.Source : iastate.edu