Preemergence (PRE) herbicides may affect the ability to reestablish warm-season turfgrasses in winter-injured areas. Experiments were conducted in 1996 and 1997 to evaluate the effects of fall or spring applications of six PRE herbicides on the vegetative establishment of Tifway bermudagrass, and Meyer and El Toro zoysiagrass. PRE herbicides were applied at the recommended rates during the fall of 1995 and 1996 and at recommended or reduced rates during the spring of 1996 and 1997. Oxadiazon, benefin plus trifluralin, or oryzalin did not inhibit Tifway bermudagrass or zoysiagrass sprig establishment. Fall applications of prodiamine and dithiopyr at full rates suppressed Tifway bermudagrass establishment as much as 25%, but recovery was evident by the end of the growing season. Reduced spring rates of prodiamine diminished its suppressive effects on Tifway establishment. Zoysiagrass establishment was suppressed as much as 20% by full or reduced rates of prodiamine but was less affected by dithiopyr. Pendimethalin had lesser and briefer suppressive effects than prodiamine and dithiopyr had on either species. Results suggested that avoidance of or reduced rates of prodiamine or dithiopyr may be warranted in areas prone to winter injury.

Nomenclature: Benefin; dithiopyr; oryzalin; oxadiazon; pendimethalin; prodiamine; trifluralin; bermudagrass, Cynodon transvaalensis Burtt-Davey × C. dactylon (L.) Pers. ‘Tifway’; zoysiagrass, Zoysia japonica L. ‘Meyer’, ‘El Toro’.

Additional index words: Application timing, vegetative turfgrass establishment.

Abbreviations: POST, postemergence; PRE, preemergence; WAE, weeks after establishment.