Enhancing the margin of selectivity of RPA 201772 inZea mayswith antidotes

Abstract

The antidotes dichlormid, MON-4660, CGA-154281, R-29148, and MON-13900 were tested in the greenhouse to protectZea maysL. (corn) against RPA 201772 injury. High rates of RPA 201772 injured four Z.mayshybrids > 30%. R-29148 and MON-13900 were the most effective of the five antidotes evaluated. R-29148 applied at rates ⩾ 45 g ha−1provided excellent protection against RPA 201772 injury and also prevented injury toZ. maysfrom diketonitrile, the active metabolite of RPA 201772. In laboratory studies, R-29148 did not alter absorption of14C-RPA 201772 from soil; however, R-29148 significantly enhanced the rate of RPA 201772 metabolism and inactivation inZ. mays.The mixed function oxidase inhibitor piperonyl butoxide (PBO) increased RPA 201772 injury on all hybrids. These results demonstrate thatZ. maystolerance to RPA 201772 can be enhanced with the use of antidotes such as R-29148 and MON-13900, that R-29148 protectsZ. maysfrom RPA 201772 and diketonitrile by the enhancement of metabolism, and that oxidative reactions may be involved in the metabolism of RPA 201772 inZ. mays.