GRANT COUNTY, N.D. — A super weed that can devastate corn and soybean crops and is strong enough to stop combines has been confirmed in Grant County.

It's the sixth North Dakota county that Palmer amaranth has been documented in since the aggressive pigweed species was first confirmed in soybeans in southeastern North Dakota's McIntosh County a year ago.

The weed can grow as tall as 7 feet and produce hundreds of thousands of seeds. It's able to resist many herbicides. A heavy Palmer amaranth infestation can cut soybean yields by as much as 79% and corn yields by up to 9%, according to research by Purdue University.

It's native to the desert regions of the southwestern U.S. and northern Mexico, but it has slowly spread to southeastern and Midwestern states and in recent years has moved into the Upper Midwest. Even before it did so, the threat from Palmer amaranth was considered so great that North Dakota State University Weed Science officials named it the “weed of the year” in both 2014 and 2015, even though it hadn’t yet been found in the state.

It's now been confirmed either by NDSU Extension specialists or through laboratory analysis in the counties of McIntosh, Benson, Dickey, Foster, Richland and Grant.

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A Grant County farmer who noticed suspect plants contacted his county weed officer, who worked with NDSU Extension to submit samples for DNA analysis to the National Agricultural Genotyping Center in Fargo, where it was confirmed as Palmer amaranth, the state Department of Agriculture said Thursday.

“I strongly encourage agricultural producers to monitor millet plantings for Palmer amaranth, as that may be the likely source of infestation,” Agriculture Commissioner Doug Goehring said. “With harvest season in full swing, farmers are encouraged to scout fields and clean excess dirt and plant debris off equipment between fields to prevent unintentional spread.”

More information on Palmer amaranth is available at https://www.nd.gov/ndda/plant-industries/noxious-weeds. To report a suspect plant, go tohttps://www.nd.gov/ndda/pa or contact a county weed officer or an NDSU Extension agent.