Palmer amaranth: It’s here, now what?
Palmer amaranth and waterhemp are two dioecious pigweed species native to North America. Waterhemp’s original range was the western Corn Belt, including Iowa, whereas Palmer amaranth originally inhabited the southwestern United States. Palmer amaranth began to spread to the southeastern United States early in the 20th century but was not listed among the most troublesome weeds of the Southeast until the late 1980s. Interestingly, this is the same time frame that waterhemp emerged as a serious management issue in Iowa and surrounding states. This paper will review the history of Palmer amaranth in Iowa, factors that contribute to its weediness, and management considerations.