On Wednesday, June 17 orange and white soybean gall midge larvae were found in soybean plants at the Eastern Nebraska Research and Extension Center near Mead, NE. Two days later small white larvae were found in Northeastern Nebraska. In addition, clear and white larvae were found in southwest Minnesota.
On June 22, larvae were also found in plants in Ida County, Iowa and southeastern South Dakota. The occurrence of these larvae in soybean plants roughly corresponds with first adult captures in the area. Specific notes on each site are as follows:
Iowa: Orange and white larvae with tell-tale signs of infestation. Most of the larvae are white to creamy orange in color. No signs of wilting plants. Larvae have not been detected at some emergence monitoring sites. At least half of the sites in the area have had adult activity within the last few days.
E-Central Nebraska: Larvae have been found in soybean plants at several sites where adult emergence has occurred. Some orange or 3rd instar larvae are present at most sites. Larvae were often found next to areas with trees or dense vegetation. No signs of wilting in soybean plants.
NE Nebraska: Larvae found on plants are mostly (75%) a mix of clear/whitish with a few that are orange in color.
South Dakota: White to clear larvae found in one site today in South Dakota.
Minnesota: Mostly clear to white larvae with some just beginning to turn orange in southwestern Minnesota.
If you are scouting for soybean gall midge, you can confine your search to the first few rows of soybean field that are adjacent to a field that was injured the previous year. Carefully fold plants over and look at the base of the plants for a dark discoloration near the soil line. If you find a discolored area on the stem peel it back to determine if white or orange larvae are present.
Many of you may be wondering about management strategies at this point in the season. With only one year of data it’s difficult to provide any strong recommendations. In 2019, insecticide applications in east-central Nebraska that were made 10 days after first adult emergence had a significant yield response.
However, with adult activity occurring for more than 10 days and larval presence observed at most of the sites, it is not clear if applications made this late would have an economic return. To stay up-to-date on adult emergence, go here.