Recent research at Mississippi State has shown that eastern gamagrass, switchgrass, and tall fescue grown as filter strips reduce herbicide losses in runoff from cotton. Field experiments were conducted in 1997 and 1998 to evaluate the response of these perennial grasses to postemergence drift and registered rates of glyphosate and paraquat in mid-April and clethodim, fluazifop-P, glyphosate, MSMA, pyrithiobac, quizalofop-P, and sethoxydim in early June. Results indicate that filter strip implementation will not simply involve establishment and maintenance. In most instances, reductions in harvested biomass were as high or higher than visual injury assessments in mid-June. This finding suggests an inability of these perennial grasses to recover from an accidental overspray or drift, within the year of the event. Management decisions must be made to protect the filter strips from contact with herbicides used in the production system to ensure filter strip integrity and survival.
Nomenclature: Clethodim; fluazifop-P; glyphosate; MSMA; paraquat; pyrithiobac; quizalofop-P; sethoxydim; eastern gamagrass, Tripsacum dactyloides L.; switchgrass, Panicum virgatum L. #3 PANVI; tall fescue, Festuca arundinacea Schreb. # FESAR; cotton, Gossypium hirsutum L. # GOSHI.
Additional index words: Drift rates, filter strip integrity, runoff.
Abbreviation: POST, postemergence.