Corn rootworm, soybean gall midge, tar spot, drought stress, and weed control issues are some of the common issues or questions Iowa State University Extension and Outreach Field Agronomists have seen or heard about the past couple of weeks. Read on for more specifics about what’s happening around the state.
North Central Iowa
Two male adult soybean gall midges were found in emergence cages at the Northwest Research and Demonstration Farm near Sutherland on June 6. This is about one week earlier than previous first captures in Iowa since we started monitoring emergence in 2019. The first Midwest report of soybean gall midge emergence in 2023 was May 31 near Mead, Nebraska. You can keep up with soybean gall midge emergence at soybeangallmidge.org/.
Several labs in the Midwest have been monitoring the distribution of soybean gall midge in Iowa since 2018. Last year, we sampled many counties in western Iowa but only confirmed three new counties. This year, we focused on the counties just east of the distribution in 2021 and were able to confirm eight new counties in Iowa that had soybean gall midge: Humboldt, Kossuth, Palo Alto, Pocahontas, Polk, Ringgold, Warren, and Webster (Figure 1). Iowa now has 42 counties confirmed with soybean gall midge, nearly half of the state.
While most areas received some needed rain last week, some areas in Western Iowa continue to miss out on the rain or get minimal amounts of rain and it’s starting to show more in the crops. Getting out in the fields, some pests or issues observed by ISU Extension Field Agronomists included corn rootworm larvae, Japanese beetles, stink bugs, herbicide damage, and some nutrient deficiencies. Read on for more specifics on what’s happening across the state.
Northwest Iowa
This week, the first soybean gall midge adults (Photo 1) were collected in Iowa near Wall Lake in Sac County (Monday) and near Sutherland in O’Brien County (Thursday). This is similar to when soybean gall midge emergence was first detected in Iowa in 2021. The first Midwest report of soybean gall midge emergence in 2022 was on June 7 near Davey, Nebraska. You can keep up with soybean gall midge emergence at soybeangallmidge.org/.
Soybean gall midge (Resseliella maxima) is a new pest of soybean in the Midwest. Infestations begin at and are generally confined to field edges in most fields; however, smaller fields may see field-wide infestations. Research is ongoing to develop a colony for research purposes, understand soybean gall midge biology, and develop management recommendations.
Corn rootworms, spider mites, soybean gall midge, and the hot and dry conditions were common questions or issues received or observed by ISU Extension and Outreach field agronomists this past week. Read on for more specifics about what’s happening around the state.
Northwest Iowa
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.
ISU Extension and Outreach field agronomists, Meaghan Anderson and Angie Rieck-Hinz, recently partnered with their extension colleagues at the University of Minnesota to organize and deliver the second webinar series, Essential Row Crop Management. This series featured four topics discussing mid-season crop management. The topics included Tar Spot identification and in-season management, Soybean Aphid IPM, Corn Rootworm Management and Soybean Gall Midge update.
Soybean gall midge was confirmed as an economic pest of soybean in 2018. Worldwide, it is only known to occur in five states in the Midwestern US (Figure 1). Research began in 2019 to monitor the emergence of adults and incidence of larval feeding, as well as management options for the pest. This year, soybean gall midge adults were first collected on June 12 and larvae were detected in soybean on June 23.
