Evaluation of 2,4-D Amine, Glyphosate, 2,4-D Amine plus Glyphosate DMA and 2,4-D Choline/Glyphosate DMA for Their Efficacy on Glyphosate Susceptible and Resistant Canada Fleabane Populations

Abstract

The 2,4-D choline/glyphosate DMA formulation has reduced drift and volatility compared to the amine or ester formulation of 2,4-D and therefore is advantageous compared to a tank mix of 2,4-D amine or ester with glyphosate. The objective of this research was to compare the control of glyphosate susceptible and glyphosate resistant Canada fleabane with 2,4-D choline/glyphosate DMA with 2,4-D amine, glyphosate, and a tank mix of 2,4-D amine and glyphosate. Ten rates of 2,4-D amine (0 - 6708 g &middot ae &middot ha^-1), glyphosate (0 - 7052 g &middot ae &middot ha^-1), a tank mix of glyphosate plus 2,4-D amine (0 - 7052 g &middot ae &middot ha^-1 + 0 - 6708), and 2,4-D choline/glyphosate DMA (0 - 13760 g &middot ae &middot ha^-1) were examined in the greenhouse for the control of two susceptible (GS) and two resistant to glyphosate (GR) Canada fleabane biotypes. The tank mix of 2,4-D amine plus glyphosate and 2,4-D choline/glyphosate DMA provided equivalent control of the GR Canada fleabane biotypes at 35 days after the application (DAA). The 2,4-D choline/glyphosate DMA treatment was more efficacious than the tank mix on the GS biotypes. Glyphosate (880 g &middot ae &middot ha^-1) provided 50% and 100% control of the resistant and susceptible biotypes, respectively. The 2,4-D choline/glyphosate DMA formulation and the tankmix of 2,4-D amine and glyphosate provided similar control of GR Canada fleabane.