Topramezone As a Bermudagrass (Cynodon dactylon [L.] Pers. var. dactylon x C. transvaalensis Burtt-Davy) Suppressant in Tall Fescue (Schedonorus phoenix [Scop.] Holub).

In the fall of 2013 a study was initiated to observe the efficacy of topramezone as a bermudagrass (Cynodon dactylon [L.] Pers. var. dactylon x C. transvaalensis Burtt-Davy) suppressant in tall fescue (Schedonorus phoenix [Scop.] Holub ‘Bullseye’). The study is being conducted at the Western Kentucky University Farm in Bowling Green, Kentucky. Six herbicide regimens with an untreated control were implemented. Fluazifop was included in the study as a comparison. Treatments are as follows: topramezone twice in the fall and twice in the fall followed by a single spring application. Fluazifop applied twice in the fall and fluazifop applied twice in the fall followed by a single spring application. The rates for topramezone and fluazifop were 36.8 g ai ha^-1 and 147.2 g ai ha^-1 respectively. A mixture of topramezone and fluazifop was also applied twice in the fall and a mixture of topramezone and fluazifop applied twice in the fall followed by a single spring application. Rates for topramezone and fluazifop were 18.4 g ai ha^-1 and 73.6 g ai ha^-1 respectively. All treatments received 1.12 kg ai ha^-1 of triclopyr with each application except for the untreated controls. Fall applications were made on 9/10 and 10/3/2013.  Visual data on bermudagrass color, tall fescue color, turf quality, and bermudagrass cover (%) was collected. Fall data showed significant differences in bermudagrass color between the control and all herbicide treatments.  No significant differences in tall fescue color were observed.  Spring applications were made in May 2014. No differences were observed among treatments in turf quality or fescue color. The only difference in bermudagrass cover was between fluazifop applied twice in the fall at 147.2 g ai ha^-1 and a mixture of fluazifop and topramezone applied at 18.4 g ai ha-1 and 73.6 g ai ha^-1 respectively. The study is ongoing, but early data shows a significant decrease in bermudagrass color with little injury to tall fescue in all herbicide treatments compared to the control. Initial results indicate that topramezone and topramezone-fluazifop mixtures may be an effective control for bermudagrass in tall fescue turf.