Mefluidide-Bentazon Interactions on Soybeans (Glycine max) and Red Rice (Oryza sativa)

Responses of soybeans [Glycine max(L.) Merr. ‘Bragg’] and red rice (Oryza sativaL.) to postemergence applications of mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} and bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] alone and in combinations were evaluated in greenhouse studies. Soybeans were tolerant to bentazon up to the highest tested rate of 2.0 kg/ha, but their height was reduced by mefluidide at 1.0 kg/ha. Soybeans were not injured by any tested combination of the two herbicides. Bentazon applied alone at rates of 5.0 kg/ha and above had a significant effect on red rice injury. Mefluidide applied at rates above 0.25 kg/ha severely reduced height and fresh weight of red rice. When these two herbicides were combined, a synergistic reaction occurred, and the combination was much more effective in controlling red rice than was either herbicide applied alone. The addition of a surfactant significantly increased the activity of the combination on red rice up to 0.25 kg/ha of mefluidide and at all rates of bentazon.