Primisulfuron-methyl is a urea herbicide that is used on crop and non- crop areas for the control of grass weeds and many kinds of broad-leaved weeds. Primisulfuron-methyl is a selective postemergence systemic herbicide that is rapidly absorbed by plants and transported throughout the plant roots and foliage. The herbicide works by blocking cell growth in the active growing regions of the plant. Primisulfuron-methyl is practically non-toxic by ingestion, with a reported oral LD50 of greater than 5050 mg/kg in rats. Primisulfuron-methyl is practically nontoxic to wildfowl. Both bobwhite quail and mallard ducks show a high tolerance for the compound. Primisulfuron-methyl is of low to moderate persistence in the soil environment, with a field half-life of from 4 to 60 days. A representative value is estimated to be about 30 days.