Palmer amaranth biotypes resistant to glyphosate were first identified in 2011 and found in an increasing number of cotton fields in 2015. Weed management studies evaluating residual herbicides as part of a total weed management system were identified. These systems have been communicated at grower meetings, popular press articles, videos, and other reports.
New technologies including Bollgard II XtendFlex (glyphosate/dicamba/glufosinate tolerant) and Enlist (2,4-D tolerant) cotton lines were evaluated for crop tolerance and weed efficacy. These represent promising tools for managing problem weeds as well as glyphosate- resistant Palmer amaranth. Improved control of many problem annual and perennial weeds was achieved in these systems compared to glyphosate alone.