Glufosinate Antagonizes Clethodim Control of Goosegrass (Eleusine indica)

Abstract

Because of a previously reported antagonism of clethodim activity by other herbicides, greenhouse experiments were conducted to determine goosegrass control with clethodim and glufosinate postemergence alone, in tank mixtures, and as sequential treatments. Herbicide treatments consisted of glufosinate at 0, 290, or 410 g ai/ha and clethodim at 0, 105, or 140 g ai/ha, each applied alone, in all possible combinations of the above application rates, or sequentially. Glufosinate at either rate alone controlled goosegrass at the two- to four-leaf growth stage <44%, and control was less for goosegrass at the one- to two- and four- to six-tiller growth stages. Clethodim controlled two- to four-leaf and one- to two-tiller goosegrass 91 and 99% at application rates of 105 and 140 g/ha, respectively, and controlled four- to six-tiller goosegrass 68 and 83% at application rates of 105 and 140 g ai/ha, respectively. All tank mixtures of glufosinate with clethodim reduced goosegrass control at least 52 percentage points when compared to the control with clethodim alone. Glufosinate at 290 or 410 g/ha when applied sequentially 7 or 14 d prior to clethodim reduced goosegrass control at least 50 percentage points compared to the control obtained with clethodim applied alone. Clethodim at rates of 105 or 140 g/ha when applied 7 or 14 d prior to glufosinate controlled goosegrass equivalent to the control obtained with each respective rate of clethodim applied alone at the two- to four-leaf and one- to two-tiller growth stage. Clethodim should be applied to goosegrass no larger than at the one- to two-tiller growth stage at least 7 d prior to glufosinate application or 14 d after a glufosinate application for effective goosegrass control.