Problematic weed moving into Illinois
Emergence, stress tolerance, and growth rate are factors that make Palmer amaranth particularly noxious. Hager said it tends to display a prolonged emergence pattern with higher germination rates at shallow seed depths. Palmer amaranth can tolerate high temperatures and dry soil conditions better than any other Amaranthus species. It has an excessive growth rate, which is evident in southern regions.
These factors, coupled with resistance and competitive ability, create a need for management practices.
“The most consistent management for corn and soybean involve an integrated approach that utilizes soil-applied herbicides, postemergence herbicides and mechanical cultivation,” Hager said. “The management practices for Palmer amaranth are very similar to those recommended for waterhemp.”
Hager said time application can have a significant impact on weed control. It is critically important to remember that Palmer amaranth can grow over one inch per day. Delaying applications of postemergence herbicides is not recommended.