Minnesota Ag Connection - First Time in 60 Years in U.S., Invasive Spotted in Minnesota

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First Time in 60 Years in U.S., Invasive Spotted in Minnesota
Minnesota Ag Connection - 09/29/2020

An invasive vine not seen in the United States in six decades has been discovered in Stearns County. Sherry Kutter, a University of Minnesota Extension Master Naturalist, first spotted the vine along the Lake Wobegon Trail in Holdingford. Officials have identified it as rough potato (Metaplexis japonica), a type of vining milkweed.

Rough potato is native to eastern Asia. It has not been previously reported in North America except in 1958 in cornfields near the Iowa State University campus in Ames where it may have been part of a research project during World War II. How rough potato arrived in Holdingford is a mystery.

Bob Dunning, Stearns County agricultural inspector, mapped the vines locations and notified landowners. The densest infestations are along the South Two River near a ballfield. Bob said "I was surprised by the number of locations I found it in once I began scouting for it. I'm grateful to Sherry for discovering this issue before it had become even more widespread. Rough Potato is a very aggressive climber and it has an amazing ability to completely cover other vegetation."

Because of the magnitude of the infestations, the Stearns County Parks Department, Conservation Corps Minnesota (CCM), and the Minnesota Department of Agriculture (MDA) began removing thousands of seedpods, each containing many seeds. This was done to prevent the infestation from spreading. Based upon experience with related vining milkweeds, a combination of herbicide treatment and manual removal over several years will bring down the infestations.

"While we may never know how rough potato got to Stearns County, we can be diligent so this and other invasive plants don't spread throughout Minnesota," said Monika Chandler, MDA invasive species specialist. "Seeds and plant parts like to hitch a ride, so cleaning equipment, pets, and our clothes before leaving an area can help prevent the spread of unwanted plants."

There are no vining milkweeds native to Minnesota. Both black and pale swallow-worts are vining milkweeds and have been found at a limited number of locations in the state. If you see a vining milkweed, which has a distinctive milkweed seedpod, in Stearns County report it to Bob Dunning at Robert.dunning@co.stearns.mn.us or 320-656-6578 or in other counties report it to the MDA's Arrest the Pest line at arrest.the.pest@state.mn.us or 1-888-545-6684.

Work done by CCM and the MDA was supported by the Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizens Commission on Minnesota Resources.

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