A small, slender fly has soybean researchers landing in a state of concern.  

Through soy checkoff-funded research, scientists have been carefully writing their playbook to defend soybean gall midge, a species that attacks soybeans in the Upper Midwest. Since its discovery in 2018, the soybean gall midge has made its way to the southwest corner of Minnesota.  

“It has the potential to be an extremely damaging pest,” David Kee, director of research for Minnesota Soybean Research & Promotion Council, said. “It is extremely damaging in Nebraska and Iowa, but we don’t have a big enough population here for it to be that way yet.” 

Signs of soybean gall midge 

The symptoms of soybean gall midge are identifiable after the V2 soybean growth stages. The most obvious signs include larvae underneath the epidermis of the soybean stem, typically at the base of the plant and dark discoloration at the base of the stem.  

“We’ve been working diligently with certified crop advisors to be on the lookout for it,” Kee said. “We’ve done surveys, and more are underway.”  

Infestations are most likely on field edges near fields where soybeans were planted the previous year.  

Potential impact 

While it has yet to settle too far into Minnesota, soybean gall midge has made an impact in the Upper Midwest, leading to stunting, wilting and even the death of soybean plants. The University of Minnesota has also recorded yield reductions, especially on field edges.  

“Prior to 2017, it was a completely unknown insect, with zero documentation on it,” Kee said. “So, it’s important to note that we’ve got less than a decade of knowledge on this beast.” 

New research underway 

With little information about this pest, what does the defense playbook look like for researchers? University of Minnesota Extension has been hard at work to lay out its game plan.  

“There is new research being done both culturally and chemically, all methods of control,” Kee said. “We’re also doing more in-depth research on what temperature it needs for it to survive Minnesota winters.” 

Kee said research has found that for short-term exposure, soybean gall midge has the ability to survive in negative 40 degrees Fahrenheit, while its long-term survival rate is still being conducted.  

“Our biggest concern right now is, how do we control this if we get populations large enough to be economically damaging?” Kee said. “The more we know about it, the more we can figure out how to control it.” 

You can learn more about research efforts surrounding soybean gall midge here. 

If you suspect you have a soybean gall midge infestation, contact U of M Extension researcher Robert Koch at koch0125@umn.edu. 

“Soybean checkoff-funded research has provided much of what we know about this insect,” U of M Extension Researcher Bruce Potter said.