Palmer amaranth with resistance to one or more herbicides is one of the most difficult weeds to manage in soybeans. If you have herbicide-resistant Palmer amaranth in your soybean fields, it is important to follow the steps below for best management. Additionally, cultural practices such as earlier planting, narrow row spacing and optimum planting populations can increase the soybean plant’s ability to compete with this weed and will also improve the consistency of the herbicide programs listed below.
While following these strategies may not be 100 percent effective, they can substantially reduce herbicide-resistant Palmer amaranth populations. Additional cultural control measures, such as hand-weeding, should be implemented to eliminate any remaining herbicide-resistant Palmer amaranth plants from the field. It is also important to manage Palmer amaranth around field edges and ditch banks. Remember, one female plant can produce upward of 600,000 seeds per plant. It is important to reduce seed production from this weed to stop its further spread. If you think that you have this weed or other glyphosate-resistant weeds in any of your fields, make sure these are the last fields that you harvest. This will reduce the transportation of resistant weed seed to your other fields.