Common Name: Palmer Amaranth
Alternate Names: Palmer pigweed, careless weed
Scientific Name: Amaranthus palmeri S. Watson
All above and below ground parts of the plant must be destroyed. Additionally, no transportation, propagation, or sale of these plants is allowed. Failure to comply may result in enforcement action by the county or local municipality. Minnesota Noxious Weed Law.
Palmer amaranth is an annual plant native to the arid southwestern United States and northwestern Mexico. It is a traditional food of Native Americans including the Navajo, Pima, Yuma and Mohave. Its life-cycle is adapted to desert conditions; it will germinate and grow to quickly produce abundant seed when water is available. Palmer amaranth was accidentally introduced to the southeastern US.
Palmer amaranth developed resistance to multiple classes of herbicides and their different modes of action making it challenging to control. Palmer amaranth seed was accidentally moved, perhaps with cotton meal, and continues to spread. It is causing extensive corn and soybean crop losses in many areas.
Learn more about Palmer amaranth in Minnesota.
Palmer amaranth is adapted to the arid habitat of the desert southwest. Outside of its native range, Palmer amaranth has been documented in annual row crop fields and disturbed, sunny areas.
Seed is the means of spread and female plants are prolific seed producers. A study in Missouri documented more than 250,000 seeds produced per plant. Seed can be spread in water movement, by wildlife and via agricultural practices such as plowing, harvesting and spreading manure.
Palmer amaranth is documented in 28 states including neighboring South Dakota, Iowa and Wisconsin. It has been documented in Lyon and Yellow Medicine Counties in Minnesota.
Palmer amaranth competes aggressively with crops. 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.
Palmer amaranth can be toxic to livestock if the concentration of nitrates in the leaves is high.
MDA Noxious Weed Program
County Ag Inspectors