Tolerance of Turf-type Tall Fescue Established from Seed to Postemergence Applications of Mesotrione and Quinclorac

Abstract

Research was conducted to evaluate the tolerance of tall fescue to mesotrione applied during establishment from seed. Nine field studies were conducted over a 3-year period (2004–2006) near Knoxville, Tenn., to evaluate the tolerance of seedling tall fescue [Schedonorus phoenix (Scop.) Holub] to mesotrione and quinclorac. The first evaluated tall fescue tolerance to single and sequential applications of mesotrione compared with quinclorac (multiple application study). The second evaluated the timing of mesotrione application on tall fescue injury and establishment (timing study). In the multiple application study, all treatments injured tall fescue 23% or less. Quinclorac reduced tall fescue groundcover up to 17% 63 days after emergence (DAE). Mesotrione at 0.28 kg·ha−1 applied 28 and 42 DAE or 14, 28, and 42 DAE decreased groundcover only 4% and 6% 63 DAE. In the timing study, mesotrione at 0.28 kg·ha−1 applied at 7 and 28 DAE injured tall fescue 17% to 21% 7 and 14 days after application; however, injury subsided to less than 10% by 28 days after application. Only mesotrione at 0.28 kg·ha−1 applied 7 DAE resulted in delayed tall fescue groundcover at 70 DAE. Variation was observed in Fall 2005 evaluations compared with other evaluations, which may be attributable to delayed seeding date and cool, wet conditions.