Methiozoline was applied to creeping bentgrass golf course turf as fall, spring, and fall followed by spring applications, in order to assess seasonal timing response for Poa annua control/suppression. Four applications were made 10-14 days apart at the rate of 0.51 lbs./M and watered in immediately after application.  Poa reductions did not occur until after the fourth and final applications were made.  Annual  bluegrass  control was 95% or greater when applied at both high and low elevation locations. Annual bluegrass did return at the low elevation site (Tucson), resulting in 75-80% control.  Some thinning (loss of apparent density) occurred in the spring at the high elevation location from fall applied methiozoline.  In a previous study, spring applications only, produced control in the range of 65-70% on low elevation bentgrass greens.