Response of 17 Species of Container-Grown Woody Landscape and Foliage Plants to Four Postemergence Herbicides

Abstract

Postemergence applications of 2 rates of Whip [fenoxaprop-ethyl) (ethyl 2-[4-[(6 chloro-2-benzoxazolyl) oxy]-phenoxy] propanoic acid), Assure (quizalofop-ethyl) (2-[4-[6-chloro-2-quinoxalinyl) oxy]-phenoxy]-propanolc acid, Fusilade 2000 (fluazifop-p-butyl) (R-butyl 2-[4-(5) trifluoromethyl-2-pyridyloxy)-phenoxy] propanoic acid), and Poast (sethoxydim) (2-[1-(ethoxyamino) butyl]-5-[2-(ethylthio) propyl 1]-3-hydroxy-2 cyclohexene-l-one) were evaluated for phytotoxicity to 17 species of container-grown woody landscape and foliage plants and control of large crabgrass (Digitaria sanguinalis L.). Crabgrass plants were treated at the 2 to 4 and 8 to 10 leaf stages and were grown under both full sun and 40% shade. Each herbicide injured at least one species. Fusilade 2000 injured the fewest species, while Poast injured the most. Under 40% shade, control of crabgrass with 2-4 leaves was acceptable with all herbicides except 0.28 kg/ha (0.25 lb/A) Whip. All herbicides were effective when applied in the 8-10 leaf stage of growth. In full sunlight, excellent control of crabgrass at the 2-4 leaf stage was obtained with all herbicide treatments except Poast. Two weeks after application to the 8-10 leaf stage, the best control was obtained with Whip; however, by the end of 8 weeks, all treatments, except Poast, provided excellent control.