Tuesday, November 6, 2007
170-11
Annual Bluegrass Control in Perennial Ryegrass and Tall Fescue with Bispyribac Sodium.
Field studies were conducted in the summer of 2006 and 2007 to evaluate the response of tall fescue ‘Avenger’, and perennial ryegrass ‘Gator 3’ to bispyribac-sodium herbicide. Annual bluegrass control was also evaluated. In 2007 fine fescue ‘Ambassodor’ was also included. Sequential applications of bispyribac-sodium were applied at rates ranging from 37 g ai/ha to 296 g/ha at approximately a three week interval. Experiments were initiated on May 30 and May 31 in 2006 and 2007, respectively. All treatments were applied using a single nozzle CO2 pressured sprayer calibrated to deliver a total of 375 L ha-1. Nozzles used were 9504E and CO2 regulators were set for 220 kPa. Experimental design was a randomized complete block with four replications. Turfgrass chlorosis was rated on a percent scale where 0 equaled no chlorosis and 100 equaled complete desiccation. Annual bluegrass cover was evaluated prior to herbicide application and 10 weeks after initial treatment (WAIT). In 2006, bispyribac-sodium caused some chlorosis to tall fescue and perennial ryegrass, however injury did not exceed 20%. The highest levels of chlorosis were observed 10 days following the sequential application of bispyribac-sodium at 222 and 296 g/ha. All bispyribac-sodium treatments provide substantial control of annual bluegrass but rates exceeding 74 g/ha were required to obtain nearly complete control, especially in perennial ryegrass. In 2007, tall Fescue and perennial ryegrass injury did not exceed 5% at any evaluation time. Fine fescue was not injured by bispyribac-sodium. 6 WAIT, annual blue grass control was only 24, 65, and 78% in tall fescue when bisbyribac-sodium was applied at 74, 148, and 222 g/ha, respectively. However, 296 g/ha provided nearly complete control. Control levels in perennial ryegrass tended to be greater but rates above 74 g/ha were required to achieve 80% or greater control.
Presentation