This pesky weed is creeping into Ohio crops. Its resistance to certain herbicides makes very hard to get rid of. So, what do you need to know about Palmer amaranth?


What is it?


Palmer amaranth is a pigweed species that is native to areas of northwestern Mexico and the southwestern United States. Within those regions, the leaves and seeds of the plant were used as a source of food by Native American tribes. It can be easily confused with other pigweed species if one does not know its specific characteristics:

  • Smooth stem
  • Long petioles (“stem” of leaf that attaches the blade of the leaf to the plant’s stem)
  • Oblate or diamond shaped leaves 
  • The female Palmer amaranth plants have very large seed heads that can reach to a height of 3 feet in length.


How did it get here? What problems is it causing?


Palmer amaranth in a Georgia field (University of Minnesota)

The transfer of seeds and plants via human activity is the primary reason for the spread of the plant from its native region. In Ohio, Palmer amaranth seems to be coming in by the use of cotton feed products and contaminated farm equipment. There have also been a few instances of contaminated Conservation Reserve Enhancement Program (CREP), cover crop, and wildlife seed. As of late 2016, Palmer amaranth had been identified in 18 counties within Ohio.

Palmer amaranth has become a problem species in areas where it is not native due to the high volumes of seed produced (100,000 to 500,000 seeds per plant), adaptability, and its ability to resist glyphosate and ALS inhibitors. As a result, this plant can cause significantly diminished crop yields and farm income when not controlled. 


How can you help stop the spread?


There are many ways you can prevent the spread of Palmer amaranth:

  1. Be able to identify Palmer amaranth.
  2. Use residual herbicides in corn and bean fields.
  3. Do not run combines through infected patches.
  4. Remove the plant before it produces mature seeds.
  5. Avoid using cotton feed products.
  6. Contact the following information if you have Palmer amaranth.

If you believe that Palmer amaranth is present in your fields you can contact Mark Loux with OSU at 614-292-9081 or The Ohio Department of Agriculture will also come and sample Conservation Reserve Program (CRP), cover crop, and wildlife seed for free to test for traces of Palmer amaranth seed. If you would like more information on the testing or would like to have the testing done, contact the ODA at (614)-728-6410. Mailed samples will also be taken, however, there will be a charge associated.


***Article written by Christina Slover with Pheasants Forever. Sources: Ward, Sarah M., Theodore M. Webster, and Larry E. Steckel. “Palmer amaranth (Amaranthus palmeri): a review.” Weed Technology 27.1 (2013): 12-27. “Palmer amaranth.” OSU Weed Management- Information about weeds and herbicides for the agricultural community. The Ohio State University. Web. 10 April 2017.

About Sarah Schott

I have enjoyed hunting, fishing, and the outdoors my entire life. My enjoyment of writing, reading, and teaching others leads me to want to share my passions of the environment. I have also found conservation to be very important and I am well aware of how important conservation choices are! Through my work with the District, I like to deliver information that is helpful, inspiring, and challenging for our readers to make even better conservation choices of all our natural resources!

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