Fluazifop-P, applied in the spring or fall and pronamide, applied in the fall only, reduced quackgrass infestation in established alfalfa and increased the dry matter yield of alfalfa. Herbicides did not improve alfalfa in vitro digestibility or crude protein content. Average residues of fluazifop-P in alfalfa treated with rates of 0.25 or 0.5 kg ai ha–1, were 0.1 mg kg–1 when harvested 280 d after application, and 0.06 mg kg–1 when harvested 295 d after application. Average residues in alfalfa harvested 41 and 55 d after application were 0.13 mg kg–1 and 0.1 mg kg–1, respectively, with a 0.25 kg ha–1 treatment and 0.19 mg kg–1 and 0.05 mg kg–1, respectively, with a 0.5 kg ha–1 treatment.
