Long-Term Management of Palmer Amaranth (Amaranthus palmeri) in Dicamba-Tolerant Cotton

Abstract Research was conducted from 2011 to 2014 to determine weed population dynamics and frequency of glyphosate-resistant (GR) Palmer amaranth with herbicide programs consisting of glyphosate, dicamba, and residual herbicides in dicamba-tolerant cotton. Five treatments were maintained in the same plots over the duration of the experiment: three sequential POST applications of glyphosate with or without pendimethalin plus diuron PRE; three sequential POST applications of glyphosate plus dicamba with and without the PRE herbicides; and a POST application of glyphosate plus dicamba plus acetochlor followed by one or two POST applications of glyphosate plus dicamba without PRE herbicides. Additional treatments included alternating years with three sequential POST applications of glyphosate only and glyphosate plus dicamba POST with and without PRE herbicides. The greatest population of Palmer amaranth was observed when glyphosate was the only POST herbicide throughout the experiment. Although diuron plus ...