Postemergence Tall Fescue (Festuca arundinacea) Control at Different Growth Stages with Glyphosate and AC 263,2221

Abstract

Effective methods are needed to eradicate tall fescue (Festuca arundinacea) and convert tall fescue fields into habitats more suitable to wildlife species. The objectives of this study were to determine the efficacy of (1) a single glyphosate application during the spring or fall and (2) AC 263,222, alone and in combination with glyphosate, applied during four different tall fescue growth stages for control of established tall fescue. Studies were conducted during 1996 to 1998 in fields dominated by tall fescue located in central Kentucky. Pre- and posttreatment plant communities were described to quantify differences in vegetative characteristics due to herbicide applications. Glyphosate at 2.2 kg ai/ha applied during the spring or fall was effective in reducing tall fescue to less than 12% cover. AC 263,222 at 0.2 kg ai/ha, AC 263,222 at 0.2 kg/ha plus glyphosate at 0.6 kg/ha, or AC 263,222 at 0.2 kg/ha plus glyphosate at 1.1 kg/ha applied during the spring growth, boot, summer dormancy, and fall growth stages were equally effective, reducing tall fescue cover to less than 3% at 2 to 7 mo after treatment. Glyphosate and AC 263,222 are effective tools for the initial removal of tall fescue.Nomenclature: AC 263,222, (±)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid; glyphosate, N-(phosphonomethyl)glycine; tall fescue, Festuca arundinacea Schreb. #3 FESAR.Additional index words: Fescue conversion.Abbreviations: NWSG, native warm-season grasses; OM, organic matter; SE, standard error of the mean; MAT, months after treatment.