Influence of Thiameturon and DPX-L5300 on Wild Oats (Avena fatua) Control with Barban, Diclofop, AC 222,293, and Difenzoquat

Abstract

In field studies, wild oat control with AC 222,293 and difenzoquat was not reduced when each herbicide was applied in combination with thiameturon or DPX-L5300. Mixtures of barban with thiameturon gave wild oats control similar to barban applied alone, but mixtures of barban with DPX-L5300 sometimes gave less wild oats control than barban applied alone. Control was reduced when diclofop was applied in combination with thiameturon in 1985 but not in 1986. When antagonism occurred, addition of crop oil concentrate (COC) at 1.2 L/ha to the diclofop-thiameturon spray mixture overcame the antagonism. When diclofop was applied in combination with DPX-L5300, control was reduced and antagonism could not be overcome by increasing the diclofop rate or by adding COC to the spray mixture. In greenhouse studies the inert ingredients in the thiameturon and DPX-L5300 formulations did not antagonize diclofop activity on wild oats. TLC analysis of14C-diclofop solutions with and without thiameturon or DPX-L5300 revealed neither degradation products of diclofop nor evidence of complexing between diclofop and thiameturon or diclofop and DPX-L5300. Diclofop antagonism by thiameturon or DPX-L5300 was not due to a chemical or physical interaction between the herbicides in the spray mixture.