||I implemented two studies in northern Alabama to determine effective herbicide combinations that would kill common bermudagrass (Cynodon dactylon) and replace that community with native warm-season grasses (NWSG). The first study was implemented in spring 1999. The site was burned in April prior to initial herbicide application in May. I implemented the following treatments for the first study: 2.2 kg ai/ha glyphosate, 2.2 kg ai/ha glyphosate plus 0.2 kg ai/ha imazapic at seeding, 2.2 kg glyphosate plus 0.05 kg ai/ha imazapic,
2.2 kg ai/ha glyphosate, 0.28 kg ai/ha imazapyr plus 0.2 kg ai/ha imazapic at seeding, 0.2 kg ai/ha clethodim plus 0.2 kg ai/ha imazapic, and 0.2 kg clethodim plus 0.05 kg ai/ha imazapic at
seeding. The NWSG were no-till drilled into the existing sod at a rate of 6.9 kg PLS/ha in early May. The best treatment for killing common bermudagrass consisted of burning in late spring,
allowing the grass to regrow to a height of 5 to 8 cm, followed by an application of imazapyr at 0.28 kg ai/ha and glyphosate at 2.2 kg ai/ha with a second application of 0.2 kg ai/ha imazapic a
month later. This treatment reduced the vegetative cover of bermudagrass to less than 1%, but it was not the best treatment for establishing NWSG. NWSG cover was less than 2% at the end of
the first growing season but was more than 40% by the end of the second growing season. The best treatment for establishing the NWSG was burning followed by an application of 2.2 kg ai/ha
glyphosate in April with 0.2 kg ai/ha imazapic at seeding a month later. Bermudagrass cover was reduced to 25% by the end of the first growing season, but the NWSG responded favorably.
NWSG cover was 69% at the end of the second growing season. The following treatments were evaluated in the second study: 5.5 kg ai/ha glyphosate, 3.6 kg ai/ha clethodim plus 5.5 kg ai/ha
glyphosate, and imazapyr plus 5.5 kg ai/ha glyphosate. All the plots received an application of 0.1 kg ai/ha imazapic at seeding for residual weed control. The imazapyr and clethodim plots
reduced the percent cover of bermudagrass to 31.3 and 30.6% respectively compared to the glyphosate (91.9%) and control (98.3%) plots. The number of seedlings also differed by treatment type and ranged from 4.1 seedlings/square meter in the control to 13.3 seedlings/square meter in the clethodim plots. The percent cover by the NWSG was higher in the imazapyr/glyphosate (33% cover) and clethodim/glyphosate (37% cover) plots when compared
to the glyphosate (6% cover) and control (1% cover) plots. The results of these studies show common bermudagrass can be converted to NWSG, but it is paramount to kill as much bermudagrass as possible prior to seeding NWSG. Imazapic is also a necessary component to
provide residual weed control.