Potential Mechanisms for Bentazon Antagonism by Haloxyfop

Abstract

The antagonism of the methyl ester of haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy propanoic acid} by bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide] was evaluated through studies of absorption and translocation in yellow foxtail [Setaria lutescens(Weig. ex Stuntz.) Hubb. # SETLU]. Leaf penetration of haloxyfop was reduced 37% in the presence of bentazon. Bentazon had no effect on translocation from the treated leaf. Direct chemical interactions and contact activity by bentazon do not account for the reduced uptake of haloxyfop. Experimental evidence shows the benzothiadiazione structural class of chemistry to be general antagonists of absorption for foliarly applied herbicides.