Premergence (PRE) herbicides were applied to a bermudagrass golf green overseeded with ‘Laser’ roughstalk bluegrass during 1995 and 1996 to determine their effects on roughstalk bluegrass injury and on the transition from a mixed cool- and warm-season grass back to the permanent bermudagrass. Roughstalk bluegrass tolerated single March applications of trifluralin plus benefin at 2.2 kg/ha, pendimethalin at 3.4 kg/ha, dithiopyr at 0.6 kg/ha, prodiamine at 0.8 kg/ha, bensulide plus oxadiazon at 8.4 kg/ha, and bensulide at 11.2 kg/ha. A single March application of oxadiazon plus benefin at 3.4 kg/ha severely injured (35%) the overseeded turf in 1 yr, but not when 1.7 kg/ha was applied in March and repeated in May. One-half recommended rates of oxadiazon and bensulide plus oxadiazon applied in March did not cause any undesirable injury, but when repeated in May, moderate to severe injury (28 to 33%) occurred in June. Oryzalin at ≥ 1.1 kg/ha, benefin plus oryzalin at ≥ 1.1 kg/ha, and oxyfluorfen plus oryzalin at ≥ 1.7 kg/ha severely injured (≥ 35%) roughstalk bluegrass. The rate of transition of mixed roughstalk bluegrass and bermudagrass back to permanent bermudagrass was not affected by any of the PRE herbicides except when oryzalin was applied alone or in combination with benefin or oxyfluorfen.