Absorption and fate of BAY MKH 6561 in jointed goatgrass and downy brome

Abstract

Abstract To be effective, postemergence herbicides must be absorbed and translocated to sites of action in proper form and quantity. Any factor that interferes in this process may account for differential sensitivity. Adjuvant effects on foliar absorption of BAY MKH 6561 by jointed goatgrass and downy brome were evaluated under growth chamber conditions. Absorption of BAY MKH 6561 by jointed goatgrass and downy brome without adjuvants was 41 and 30% of applied, respectively, 48 h after treatment (HAT). Herbicide absorption with methylated seed oil (MSO) was significantly higher than with nonionic surfactant (NIS) 24 and 48 HAT. The addition of urea ammonium nitrate (UAN) to MSO and NIS significantly increased absorption over MSO and NIS alone 24 HAT, but absorption was similar to that obtained with MSO 48 HAT. Averaged across adjuvant combinations, jointed goatgrass and downy brome absorbed 90 and 89% of applied BAY MKH 6561, respectively, 48 HAT. BAY MKH 6561 translocation and metabolism in jointed goatg...