Keep an Eye Out for ‘Odd’ Pigweeds

August 7, 2013
ICM News

By Bob Hartzler, Department of Agronomy

Most people are aware of the concerns regarding Palmer amaranth moving into Iowa. As discussed in an earlier article, distinguishing Palmer amaranth from waterhemp can be difficult in the vegetative stage. The majority of Amaranthus plants should currently be in the reproductive stage, greatly simplifying identification. Palmer amaranth produces long terminal branches on its inflorescences, capable of reaching lengths of three feet.  The flowers of female Palmer amaranth plants have sharp bracts that are painful to the touch.


We are interested in confirming the identification of any suspected Palmer amaranth infestations in Iowa. Send images or plant samples to the following address, or contact me directly regarding suspect plants:

Bob Hartzler   

1126C Agronomy Hall

Iowa State University

Ames, IA  50010


Bob Hartzler is a professor of agronomy and weed science extension specialists with responsibilities in weed management and herbicide use. Hartzler can be reached at or 515-294-1164.


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