Abstract

The ability to selectively control a specific cool-season grass growing in a mixed stand would offer great advantages to turfgrass managers. It is common for monostands of creeping bentgrass (Agrostis stolonifera) to become infested with annual bluegrass (Poa annua). Conversely, monostands of ‘True Putt’ creeping bluegrass (Poa annua var. reptans), a commercially available perennial biotype of Poa annua, often develop bentgrass infestations. The objective of this study was to evaluate the efficacy of various herbicides for the selective control of bentgrass with minimal injury to True Putt. Nine herbicide treatments were applied to 248 cm² (38.4 in²) plugs maintained at 1.3 cm (0.51 in) in the greenhouse. The experiment was conducted twice during the winter of 2001–2002. Several ratings were made over the four week period on quality of bentgrass and creeping bluegrass and on reduction of bentgrass cover. Vantage, Image, Assure II, Fusilade II, Finale, and Balance Pro gave a minimum of 65% control with Vantage, Assure II, Fusilade II, and Finale achieving 100% control. However, Vantage was the only herbicide that provided complete control of bentgrass while causing no significant reduction in the quality of True Putt creeping bluegrass. Assure II and Fusilade II also provided complete control of bentgrass, but both had a negative impact on the quality of True Putt.