Effect of Herbicide Safeners on Sand and Little Bluestems

Abstract

Weed competition is a major factor limiting establishment of warm-season grasses. Use of preemergence herbicides in conjunction with herbicide safeners can offer a successful weed control strategy. Effects of herbicide safeners applied as seed treatments, and soil-incorporated herbicides on sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern.] and little bluestem [Schizachyrium scoparium (Michx.) Nash] were evaluated in germinator and greenhouse studies. The safeners cyometrinil ((Z)- [(cyanomethoxy)imino] benzeneacetonitrile), dichlormid (2,2-dichloro-N, N-di-2-propenylacetamide), and R-29148 (2,2-dimethyl-6-methyldichloro-acetyloxazolidine) reduced germination and shoot growth of both grasses. Sand bluestem was protected against EPTC (S-ethyl dipropyl carbamothioate) and vernolate (S-propyl dipropylcarbamothioate) by R-29148, while cyometrinil reduced EPTC damage on little bluestem. Sand bluestem treated with R-29148 tolerated 6 ppm (w/w) of vernolate or EPTC without damage. Without safener treatment sand bluestem was tolerant to metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide] (1.25 ppm), vernolate (2 ppm), and cycloate (S-ethyl cyclohexylethylcarbamothioate) (2 ppm w/w).