Broadleaf Herbicide Effects on Tall Fescue (Festuca arundinacea) Seedhead Density, Forage Yield, and Quality

Four broadleaf herbicides and combinations were compared for two years with mefluidide, a growth regulator, for effects on ‘Ky 31’ and ‘Fawn’ tall fescue. Seedhead densities averaged 33% of the check with 8.4 g ai/ha of metsulfuron, 17% with 70 g ai/ha of imazethapyr, and 9% with 280 g ai/ha of mefluidide, while forage yields were reduced to about 40% of the check. Forage crude protein (CP) concentrations were increased by mefluidide, imazethapyr, and 8.4 g/ha of metsulfuron. Neutral-detergent fiber (NDF) of Ky 31 but not Fawn forage was reduced by mefluidide, imazethapyr, and metsulfuron at 6.3 and 8.4 g/ha, but Fawn NDF was increased by dicamba plus 2,4-D. In vitro dry matter digestibility was increased by metsulfuron at 6.3 and 8.4 g/ha, mefluidide, and imazethapyr in one of two years. Adding 2,4-D to metsulfuron reduced some effects of metsulfuron. Total CP/ha was no more adversely affected by imazethapyr and metsulfuron than mefluidide. Imazethapyr and metsulfuron can thus be used to control weeds without reducing fescue forage value.