Role of metabolism in the selectivity of a herbicide, pyroxasulfone, between wheat and rigid ryegrass seedlings

Metabolism of pyroxasulfone in a tolerant crop, wheat and a susceptible plant, rigid ryegrass, was studied using 14C-pyroxasulfone. The main metabolites were a cysteine conjugate of the isoxazoline ring (M-26), deaminated M-26 (M-29) and a glucose conjugate of M-29, suggesting that the main metabolic route in both plants was the cleavage of the methylenesulfonyl linkage caused by glutathione conjugation. The difference in the metabolic activity was assumed to be one of the factors in determining the selectivity of pyroxasulfone between wheat and rigid ryegrass.