Soybean School: Gall midge heading north

Photo source: University of Nebraska–Lincoln

A new soybean pest has hit the radar screen, and it could be a threat to soybean growers across Canada.

Gall midge was first detected in Nebraska in 2011 and has since been confirmed in Iowa, Minnesota, and South Dakota. On this episode of RealAgriculture’s Soybean School, OMAFRA entomologist Tracey Baute explains that the midge is typically found inside the plant at the base of the stem. The tiny larvae deprive the plants of nutrients causing it to die off, usually by the end of June.

In the video, Baute reviews the findings of University of Nebraska-Lincoln research team members Justin McMechan, Tom Hunt, and Robert Wright who are working to understand the biology of the midge and identify control measures. She notes that if the pest is able to overwinter in the Great Plains or Iowa, “there’s good potential for it to arrive in Canada and overwinter here.”

Baute says there is a noticeable edge effect when it comes to the yield damage caused by gall midge. Yield loss can be up to 100 percent in the first 100 feet of the field and infection can move further into the field. (Story continues after the video.)

Visually, the adult midge look like mosquitos while the white or orange larvae resemble maggots. In many cases, the pest has been misidentified as sudden death syndrome, stem canker or even spray drift, because of the edge effect.

So far, the researchers have not identified an efficient means of control. In Nebraska, insecticides have not worked and currently available seed treatments may not be the answer. Control will be challenging because — like wheat and swede midge — it’s difficult to control the midge once they get inside the plant, says Baute. One control strategy that has shown promise is later planting. The Nebraska team has reported that soybeans planted in May are more severely impacted than June plantings.

Baute says it is difficult to estimate when gall midge will arrive in Canada, but she’s confident her U.S. colleagues will have significant research insights to help control the pest when it crosses the border.

Click here for more Soybean School episodes.

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