Palmer amaranth (Amaranthus palmeri) is native to the desert regions of northern Mexico and the southwestern United States,
and has spread into the Midwest, the East Coast and portions of Canada. Palmer amaranth is a relatively new introduction in Iowa,
Minnesota, South Dakota, Wisconsin and the Northwest U.S. Palmer amaranth can be distributed by birds, though livestock
feed, manure, grazing, wind, farm equipment etc. Amaranth expansion was accelerated in 2016 as an unintentional contaminant
in some native seed mixes purchased by growers participating in conservation programs. Palmer amaranth grows 1–3 inches in height per day, up to 6–8 feet tall and occasionally will reach 10 feet or more. Emergence occurs from early May through late summer and a single plant can produce over 200,000 seeds. Compounding the concern over the expansion of this highly aggressive, fast-growing weed is its resistance to herbicides. It is similar to waterhemp in its ability to rapidly evolve resistance to many herbicides used in weed management programs.
Lindsay Haines, USDA Natural Resources Conservation Service, Bob Hartzler, Iowa State University, Robert Nowierski, USDA National Institute of Food and Agriculture, Susan Ratcliffe, University of Illinois, and Jill Schroeder, USDA Office of Pest Management Policy have developed a National Pest Alert with details on this emerging weed. To download click here:
For more information about Palmer amaranth control recommendations and state resources.
