From the MDA: Update on Palmer amaranth

Reprinted from Minnesota Noxious Weeds - Palmer Amaranth

In September 2016, Palmer amaranth (Amaranthus palmeri) was initially discovered and confirmed in Minnesota. To date, isolated populations have been documented in first year conservation plantings in Yellow Medicine, Lyon, Douglas and Todd Counties. The Minnesota Department of Agriculture (MDA), University of Minnesota Extension, USDA, landowners and other partners are working to eradicate these infestations before they can spread to new areas.  Efforts to this point have been very successful.  MDA is also working closely with other state, county and federal agencies, the MN Native Seed Industry and several non-profit organizations to regularly sample and test seed sold in the state for presence of Palmer amaranth.

Why the concern? 
Palmer amaranth is a fast growing weed native to the southwestern United States and northwestern Mexico, and has spread east and north through a variety of pathways including contaminated seed, hay, livestock feed and agricultural equipment. It has developed resistance to multiple classes of herbicides and their different modes of action, making it very difficult and expensive to control. Palmer amaranth is a prolific seed producer. Up to 250,000 seeds can come from one plant. It is also highly competitive.

It has a fast growth rate of 2- 3 inches per day and commonly reaches heights of 6- 8 feet, greatly inhibiting crop growth. Reported yield losses have been up to 91% in corn and 79% in soybean in some states. The weed can also significantly increase production costs for corn, soybean, and other crops. 

Read  more about Palmer amaranth on the MN Department of Agriculture webpage