Understanding the threat of palmer amaranth

Palmer amaranth is a weed species that must be thoughtfully and carefully managed. Simply attempting to control Palmer amaranth often leads to ineffective herbicide applications, substantial crop yield loss, and increased weed infestations, said a University of Illinois weed sciences researcher.

“If ignored or otherwise not effectively managed, Palmer amaranth can reduce corn and soybean yield to nearly zero,” said Aaron Hager. “The threat of Palmer amaranth during the 2014 growing season is very real across a large portion of Illinois.”

The U of I weed science program has developed recommendations for management of Palmer amaranth in agronomic crops. These recommendations were developed in accordance with the unique growth characteristics of this weed species. The goals of the recommendations are twofold: to reduce the potential for Palmer amaranth to negatively impact crop yield, and to reduce Palmer amaranth seed production, which ultimately augments the soil seed bank and perpetuates the species.

Three general principles of Palmer amaranth management include:

1. Prevention is preferable to eradication.
2. It is not uncommon for annual herbicide costs to at least double once Palmer amaranth becomes established.
3. Control of Palmer amaranth should not be less than 100%.