Palmer: Moving On Up

Pamela Smith
By  Pamela Smith , Crops Technology Editor
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Palmer amaranth distribution in the continental U.S. Image by Andrew Kniss

Palmer amaranth may be native to the Southeast, but it has quickly shown it can be extremely adaptable. The weed was most recently found in North Dakota.

In fact, there are only a handful of states where it has yet to be identified, notes University of Wyoming weed scientist Andrew Kniss. His efforts to track the weedy tyrant show only the extreme New England states and parts of the Northwest are pigweed free--so far.

The North Dakota population was found by a farmer doing some hand-weeding. Agronomists think the population likely came from seeds dropped by migratory birds.

University weed scientists urge farmers to watch for the plant during harvest. Early detection is important for changes in management strategies. Palmer amaranth can resemble redroot pigweed, Powell amaranth and waterhemp. The leaf stem, or petiole, of Palmer amaranth is typically as long or longer than the leaf blade. Another clue is Palmer amaranth’s distinctive, long, snaky seed heads that can grow several feet long.

A video on identifying Palmer amaranth in late-season stages can be found at


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