Postemergence Weed Control with Glyphosate Plus Flumioxazin Combinations

Abstract

Glyphosate plus flumioxazin tank mixtures have become popular in the nursery production and landscape maintenance industries in the southeastern United States. Research was conducted to compare the efficacy of such a mixture relative to the components applied alone. Glyphosate, flumioxazin, and glyphosate plus flumioxazin (2 : 1, w/w) were applied POST in container trials to four weed species at a series of rates that ranged from no effect to death. Regression analyses revealed that control data from all three treatment series could be described by the four-parameter, log-logistic model. With respect to glyphosate and flumioxazin applied alone, analysis revealed that across all four species, a lower rate of flumioxazin was required for 90% control than of glyphosate. The rate of the mixture required for 90% control was generally intermediate to the components applied alone and ranged from 0.36 kg ha−1 for hairy bittercress to 1.52 kg ha−1 for eclipta. Glyphosate alone was more cost effective than either flumioxazin alone or the mixture for the POST-applied control of all four species. The popularity of the tank mixture might be the result of flumioxazin-based PRE activity that was not measured in this study.