Efficacy of Burndown with Sequential Applications for Junglerice (Echinochloa colona) Control

Abstract

Junglerice has continued to expand its range as a serious weed pest in Tennessee cotton. Both glyphosate resistance and herbicide antagonism have been documented as possible causes for poor control. Approximately 15% of junglerice populations in Tennessee have been found to be glyphosate resistant. In addition, dicamba tank mixtures with glyphosate and/or clethodim have been reported to reduce junglerice control. Due to poor in-crop control, starting clean has taken on added importance when trying to control junglerice. Therefore, research was conducted to determine the best herbicide burndown methods utilizing clethodim, dicamba, glufosinate, glyphosate, or paraquat. Paraquat alone or in tank-mixtures with glyphosate or clethodim provided poor control (< 50%). Likewise, glufosinate alone or in tank-mixture with glyphosate or clethodim provided poor control (< 35%). A dicamba + glyphosate, glufosinate + clethodim, or paraquat + clethodim application provided poor junglerice control. Regardless of which herbicides were initially applied, making a follow-up application of glyphosate or glyphosate + clethodim two weeks later provided optimal control of junglerice. In Tennessee, a glyphosate + clethodim application at 14 days before planting is recommended to control junglerice, other grasses and some broadleaf weeds, followed by paraquat at-planting to control remaining weed species.