Interaction of Acifluorfen with Fluazifop for Annual Grass Control

Abstract

In field and greenhouse studies, tank mixing 0.3 and 0.4 kg ai/ha of the butyl ester of fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid} with 0.4 kg ai/ha of acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} reduced control of large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA] and itchgrass (Rottboellia exaltataL.f. # ROOEX) compared to fluazifop applied alone in soybeans [Glycine max(L.) Merr.]. Less antagonism between the two herbicides was observed in a year when conditions were optimum for large crabgrass control with fluazifop. Application of acifluorfen 1 to 3 days before application of fluazifop decreased large crabgrass control. Antagonism between fluazifop and acifluorfen was avoided when fluazifop was applied 3 to 5 days before acifluorfen. No antagonism was observed when fluazifop at 0.3 or 0.4 kg/ha was tank mixed with acifluorfen at 0.4 kg/ha for control of itchgrass. Itchgrass was more susceptible to fluazifop than large crabgrass.