The dissipation of trifloxysulfuron in solution has not been evaluated. The objectives of this study were to evaluate the effect of spray carrier pH (pH values of 5, 7, and 9) on dissipation of trifloxysulfuron during a 21-d period and to evaluate the resulting effects on efficacy on Palmer amaranth. ANOVA of half-life values indicated that hydrolysis occurred more rapidly under acidic spray carrier pH with no differences between neutral and alkaline pH levels. Trifloxysulfuron solutions that were applied to Palmer amaranth significantly decreased dry weights compared with nontreated at all pH levels and time intervals. These results indicated that trifloxysulfuron dissipation was most rapid when the spray tank pH was more acidic, but trifloxysulfuron efficacy was not adversely affected by chemical degradation on Palmer amaranth. Data suggest that pesticide applicators may reduce trifloxysulfuron degradation in spray tanks by using neutral or alkaline spray carriers.

Nomenclature: Trifloxysulfuron, Palmer amaranth, Amaranthus palmeri S. Wats AMAPA