The Minnesota Department of Agriculture positively identified the invasive weed Palmer amaranth in Houston County last week. The MDA was contacted by the Houston County Ag Inspector after discovering several hundred plants in a small hay field. The field has since been mowed and burned off to destroy any plants, seedlings, and seeds produced this season. The source of the infestation is still under investigation.

“While we’re still trying to determine how Palmer amaranth got into the field, we’re asking farmers to scout for the weed now before harvest,” said Denise Thiede, MDA’s Seed Unit Supervisor. “The plants will be identifiable with flowering and fruiting structures. Seedhead spikes can get up to three feet long and are pricklier than waterhemp or other pigweed spikes.”

Palmer amaranth is a fast growing weed native to the southwestern United States and northwestern Mexico. It has developed resistance to multiple classes of herbicides, making it very difficult and expensive to control. It has a fast growth rate of 2- 3 inches per day and commonly reaches heights of 6- 8 feet, greatly inhibiting crop growth. Yield losses have been up to 91% in corn and 79% in soybean.

Since it was first discovered in the state in 2016, Palmer Amaranth has been found in seven Minnesota counties, including Lincoln, Lyon, Yellow Medicine, Redwood, and Jackson. If you suspect Palmer amaranth on your property, collect the whole plant and contain any seed produced. Contact the Minnesota Department of Agriculture’s Arrest the Pest line at 1-888-545-6684 or, the University of Minnesota Extension, or your local crop consultant.