Glyphosate-resistant Palmer amaranth poses an unprecedented threat in many crop production areas. Arkansas farmers have been dealing with resistant biotypes of this noxious weed since 2005, and the problem has gotten worse ever since. Fortunately, university researchers are coming to farmers’ aid with inventive solutions, according to Andrew Wargo, a business agent with Baxter Land Company in Watson, Ark. The latest idea? Simply smother the weeds with a rye cover crop.
Research continues to investigate the value of a rye cover crop for preventing weed germination.
Wargo says that University of Arkansas weed scientist Dr. Jason Norsworthy and his colleagues conducted tests the past few seasons where they planted rye in between cotton or soybean rows in the fall just prior to leaf drop. The researchers discovered that post-harvest, the rye wasn’t just covering the ground – it was covering weed seeds, too.
"The rye prevents the seeds, particularly the amaranth, from getting the sunlight they need to germinate," Wargo says. "When the rye falls down or you chemically burn it down, it lays down dead, serves as a shield and prevents germination up to about 85 percent."
A rye cover crop has two other big benefits, he adds. It prevents wind erosion, and it also puts valuable vegetative matter back into the soil. Wargo thinks farmers in his area will take note of this additional method to suppress Palmer amaranth growth. More than 80 percent of the cotton acres and 60 percent of the soybean acres in Arkansas have resistant weed populations.