Four field locations were used to compare environmental factors on efficacy of four postemergence grass herbicides in Kentucky bluegrass and bermudagrass turf. Imazaquin, BAS 514, and tridiphane were compared to fenoxaprop-ethyl, a registered herbicide, for postemergence control of large crabgrass. Best large crabgrass control was provided by BAS 514 and fenoxaprop-ethyl. Use of BAS 514 gave equal turf quality, phytotoxicity to the turf, large crabgrass control, and stand compared to fenoxaprop-ethyl. Imazaquin and tridiphane reduced turf quality and were phytotoxic to both turf types, and did not control large crabgrass adequately.