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Climate Change Impacts on Palmer Amaranth

Palmer amaranth (Amaranthus palmeri S. Watson) is an annual plant in the pigweed family (Amaranthaceae). It is native to the southwest United States/northern Mexico deserts and is currently increasing its range across the country. Palmer amaranth:

  • Is fast growing (2 to 3 inches per day and can grow more than 6 ft tall)
  • Produces small seeds that are unintentionally moved long distances    
  • Seeds can remain dormant in the soils and germinate years later
  • Is very difficult to control
  • And can develop resistance to herbicides

For these reasons, Palmer amaranth can significantly increase agriculture production costs, and may reduce yields by out-competing crops. It has been found to cause yield losses up to 91% in corn and 79% in soybeans (USDA NRCS). Therefore, it is important to be proactive in identifying and and managing this problematic weed. USDA NRCS, their partners, as well as farmers and landowners are working to eradicate these infestations before they spread to new areas.

Midwest Climate Hub fellow, Dr. Erica Kistner-Thomas is getting a jump on how the distribution of Palmer amaranth will change from current to future climate conditions. Climate change is going to benefit this heat-tolerant weed by lengthening its growing season, boosting seed production and expanding its potential U.S. geographic range.

For more on Erica’s work, check out resources below.

Peer-Reviewed Publications

Potential Geographic Distribution of Palmer Amaranth under Current and Future Climates


Superweed Palmer Amaranth is on the Move: Here’s What You Need to Know

For additional information on how to manage palmer amaranth in your field, visit USDA NRCS technical resources here.