Herbicide Treatments to Renovate Toxic Endophyte Infected Tall Fescue Pastures with ‘Jesup’ MaxQ

Abstract

Forage producers need more efficient, less risky, and cost‐effective strategies for replacing existing stands of toxic endophyte infected (E+) grass. This study addressed the efficacy of E+ tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorus arundinaceus (Schreb.) Dumort =] control using available herbicides, differing herbicide application timings, and weed control techniques and assessed the survival of E+ seed during the summer after it was produced. Two small‐plot experiments near Blairsville and Watkinsville, GA, evaluated herbicide chemistry and compared different application protocols for glyphosate at different time intervals (0, 2, 4, and 6 wk) to the use of a summer annual smother crop between split applications of glyphosate. Glyphosate allowed fewer E+ escapes than the other herbicides tested. Split applications of glyphosate at 6 wk before planting and again 1 d before planting resulted in successful eradication of the E+ tall fescue stand, fewer weeds, and a successfully established stand of nontoxic endophyte infected (NT) tall fescue. In a separate experiment at Blairsville and Watkinsville, 7.4 and 8.5 seeds per 100 seeds produced, respectively, were found to be germinable and with viable endophyte despite exposure to ambient conditions on the canopy floor in 2004. Thus, spring suppression of E+ tall fescue seedheads could reduce the risk of remnant toxic E+ seed. In field‐scale tests of the developed protocol [spring suppression of seedheads and a split application of glyphosate (6‐wk interval) before an autumn planting], E+ tall fescue stands were destroyed successfully and renovated with a NT tall fescue with a range of E+ escapes being only 0.5 to 2.5%.

Seedling Performance Associated with Live or Herbicide Treated Tall Fescue

“…General agronomic practices and recommendations are to suppress or destroy the existing sward to lessen the influence of competition from an intact tall fescue stand and then sow legumes [49]. Recent work suggests that removal of residual tall fescue biomass before sowing is more important than seeding method [32,33].…”

“…Renovating existing stands of endophyte-infected tall fescue often includes chemical elimination of the preexisting stand, sowing an annual crop, and then either respraying or sowing the desired replacement crop [32,33]. Planting into a newly killed sod may present a challenge because of the effects of decomposing crop residues [30,34] or carry-over herbicide effects especially where crop residues remain on the soil surface.…”

Replacing Toxic Tall Fescue With a Nontoxic Forage

“…Soon after the second spray, the new variety can be no‐till drilled into the killed stubble at recommended seeding rates. The spray–wait–spray method has been tested on experimental and farm scales for over 10 years in the southern United States and has consistently eradicated toxic tall fescue (Hill et al., 2010).…”

Complete Issue

“…Soon after the second spray, the new variety can be no-till drilled into the killed stubble at recommended seeding rates. The spraywait-spray method has been tested on experimental and farm scales for over 10 years in the southern United States and has consistently eradicated toxic tall fescue (Hill et al, 2010).…”