Tolerance of zoysiagrass (Zoysia spp.) cultivars to preemergence herbicides

Preemergence herbicides were applied at recommended and three times the rec ommended rates during 1995, 1996, and 1997 to eight established zoysiagrass (Zoysia spp.) cultivars. Oxadiazon was the only herbicide that did not sig nificantly reduce the quality of any zoysiagrass cultivar. The zoysiagrass cultivars had intermediate tolerance to prodiamine and pendimethalin, while oryzalin, dithiopyr, and benefin plus oryzalin caused the highest injury. 'Emerald' and 'Meyer' cultivars were least affected by herbicide applicatio n. 'Diamond,' 'El Toro,' 'Cavalier,' and 'Crowne' showed moderate injury, w hile 'Royal' and 'Palisades' had the greatest injury. When the performance of zoysiagrass cultivars was averaged across herbicides, turf quality in Ma y was best for Meyer, El Toro, and Crowne. The quality of the majority of c ultivars except for Royal improved during the slimmer and was similar to th at of Meyer by late August both years.