Hybrid Bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davy) Control with Glyphosate and Fluazifop

During bermudagrass golf course renovations, complete removal of existing bermudagrass is imperative for establishing a pure, contaminant‐free stand of a new bermudagrass cultivar. Field studies were conducted at the West Florida Research and Education Center near Jay, FL in 2001 and 2002 to evaluate hybrid bermudagrass control. Glyphosate (4.5 kg ai/ha), glyphosate (4.5 kg ai/ha) + ammonium sulfate (1 kg of N per ha), glyphosate (4.5 kg ai/ha) + fluazifop‐p‐butyl (0.4 kg ai/ha), and glyphosate (4.5 kg ai/ha) + fluazifop‐p‐butyl (0.4 kg ai/ha) + ammonium sulfate (1 kg of N per ha) were applied sequentially either two or three times at 4‐week intervals. At 12 weeks after initial treatment (WAIT) (4 weeks after final herbicide application), glyphosate + fluazifop‐p‐butyl and glyphosate + fluazifop‐p‐butyl + ammonium sulfate applied three times provided 99% bermudagrass control. Single‐degree‐of‐freedom contrast analysis indicated that there was a 12% increase in control for three versus two applications at 12 WAIT (P < 0.01). Contrast analysis also indicated a 7% (P < 0.01) increase in bermudagrass control 12 WAIT with fluazifop‐p‐butyl + glyphosate relative to glyphosate alone. The addition of ammonium sulfate increased control at 4 WAIT (P < 0.05) by 4%, however, no differences in control were observed at 8 and 12 WAIT. Turfgrass managers considering bermudagrass renovation should use three applications of glyphosate + fluazifop‐p‐butyl at 4.5 + 0.4 kg ai/ha with repeat applications scheduled 4 weeks apart to obtain complete control of the existing bermudagrass.