BERMUDAGRASS CONTROL WITH TOPRAMEZONE IN TALL FESCUE.   C. Johnston and P. McCullough; Department of Crop and Soil Sciences, University of Georgia, Griffin, GA 30223. 

ABSTRACT

Field experiments were conducted in Griffin, GA to evaluate efficacy of topramezone alone or with triclopyr for bermudagrass (Cynodon dactylon) suppression in a tall fescue (Festuca arundinacea) lawn.  Three applications were made on a three-week interval beginning in July and half of each plot was overseeded with ‘Titan’ tall fescue two weeks after the third application.  Topramezone treatments alone controlled bermudagrass 6 to 54% but tank-mixtures with triclopyr increased control to 60 to 68% before overseeding in October.  All treatments provided excellent (>90%) control of smooth crabgrass (Digitaria ischaemum) except the lowest rate of topramezone alone.  Topramezone plus triclopyr treatments increased tall fescue cover to ≈50%, compared to 10% in the untreated, but overseeding after these applications increased tall fescue cover to >80% by December.  However, bermudagrass cover was similar across treatments and overseeding regimens at one year after initial treatments suggesting sequential applications in spring and the following summers will be needed for long-term bermudagrass control.