Tribenuron-methyl Mode of action Selective, post-emergence herbicide, acting primarily through foliar uptake, with little or no soil activity. Tribenuron-methyl Symptoms of chlorosis appear in affected weeds in days with necrosis and death occuring after 10-25 days under optimal conditions. Tribenuron-methyl Uses Post-emergence control of broad-leaved weeds in cereal crops, including wheat, barley, oats, rye and triticale, at 7.5-30 g/ha.