Interactions of Diphenylether Herbicides with Chlorimuron and Imazaquin

Abstract

Field experiment were conducted to determine interactions of chlorimuron or imazaquin with fomesafen, lactofen, or acifluorfen on three-leaf and eight-leaf common cocklebur, hemp sesbania, pitted morningglory, and prickly sida. Antagonism was the most common interaction with common cocklebur, and was most severe with chlorimuron combined with fomesafen or acifluorfen, whereas lactofen did not antagonize common cocklebur control. Reductions in control were greater when low rates of chlorimuron were used. On three-leaf prickly sida, control synergistically increased when imazaquin was combined with fomesafen or acifluorfen, but the majority of these combinations were additive on eight-leaf prickly sida. Three-leaf pitted morningglory control synergistically increased when 36 g ai ha–1imazaquin was combined with 210 g ai ha–1fomesafen or 110 or 220 g ai ha–1lactofen. With eight-leaf pitted morningglory, synergism occurred when 2 g ai ha–1chlorimuron was combined with the high rate of any diphenylether herbicide tested, and when 36 g ha–1imazaquin was combined with 110 g ha–1lactofen or 210 g ai ha–1acifluorfen; however, at higher rates of chlorimuron or imazaquin, several antagonistic interactions occurred. Hemp sesbania was controlled over 90% by all combinations, and no interactions occurred.