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.

Nomenclature: Flumioxazin; glyphosate; eclipta, Eclipta prostrata L. ECLAL. hairy bittercress, Cardamine hirsuta L. CARHI.