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Extension asks that soybean growers fill out the online survey.

Paula Mohr, Editor, The Farmer

December 3, 2020

2 Min Read
Soybean gall midge
ON THE MOVE: Soybean gall midge was reported in 16 counties in Minnesota in 2020, two more than in 2019. The pest has been found in fields on the southwest side of the state. Farmers in Swift and Traverse counties reported the pest for the first time in 2020. Justin McMechan

University of Minnesota Extension entomologists are conducting a state-wide survey on soybean gall midge distribution.

The soybean pest was found in 16 counties in southwest Minnesota in 2020.

Soybean gall midge was first identified in the Midwest in 2018. That year, growers in western Nebraska, eastern Iowa and eastern South Dakota noticed soybeans wilting and dying, particularly along field edges. They found small orange gall midge larvae beneath brittle stem bases. Later in the season, soybean stems were breaking where the midge injury occurred. In August 2018, U-M entomologists received infested samples from Rock County and confirmed that the pest had arrived in the state. Growers in more counties reported the pest in 2019. And in 2020 in Minnesota, infested fields in Swift and Traverse counties were added to the growing list.

Bruce Potter, U-M Extension integrated pest management specialist, says soybean gall midge infestations detected thus far have been minor and not uniform in their geographic distribution.

In a previous writing, Potter said entomologists believe the larvae overwinter in soils of infested fields, with pupation and adult emergence occurring in the spring. Adult emergence begins in June and can extend into July. Although reproductive behaviors are not yet known, egg laying is suspected to occur near the base of plants, where larval infestations are typically found. Cracks in the stem epidermis and other wounds may provide sites for egg deposition or larval entry. There are at least two adult generations each year in Minnesota, he notes, adding that natural enemies of the soybean gall midge may occur but have not been documented.

Pest distribution unclear this year

Specific to the 2020 growing season, Potter says it is unclear if anything helped distribute soybean gall midge in the state.

“Earlier planting probably helped the insect, yet the warm dry spring may have hurt colonization,” he says.

Entomologists need to hear from growers to learn if they were impacted by soybean gall midge infestations in any fields. In particular, they want to learn if tillage may be a factor and impact overwintering larval survival.

“Areas of the Midwest where damage is more severe tend to be no- or minimal till,” Potter says.

Growers are encouraged to take the survey online at MN Soybean Gall Midge Survey. Please complete only one survey per farm. The survey will be available until mid-February.

Learn more about the pest online at the Soybean Gall Midge Alert Network.

To view an online map of national distribution of the pest, visit bit.ly/sgmmap.

 

 

 

About the Author(s)

Paula Mohr

Editor, The Farmer

Mohr is former editor of The Farmer.

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