Retention, absorption, translocation and distribution of sethoxydim in monocotyledonous and dicotyledonous plants*

Summary Quackgrass [ Elymus repens (L.) Gould = Agropyron repens (L.) Beauv.] and barnyardgrass [ Echinochloa crus‐galli (L.) Beauv.] were more than one hundred times more susceptible to sethoxydim than alfalfa ( Medicago sativa L. 'Saranac') or navybean ( Phaseolus vulgaris L. 'Seafarer'). Uptake of sethoxydim From soil following post‐emergence applications caused negligible reduction in E. crus‐galli fresh weight. More than 80% of foliar‐applied 14 C‐sethoxydim was absorbed within 6 h in all species. Translocation occurred in all species with accumulation of 14 C in rapidly growing plant tissues. Translocation to the roots was less than 8% of total in all species. Most of the extracted 14 C initially partitioned into an ethyl acetate‐soluble fraction. The proportion of 14 C in the ethyl acetate‐soluble fraction decreased with time with a concomitant increase of that in the insoluble fraction. Differences in the quantity of 14 C in the ethyl acetate‐soluble fraction did not account for the observed selectivity.