Influence of Herbicide Rotation Treatments on Species Composition of Weeds in Turfgrass

Abstract

DCPA (dimethyl tetrachloroterephthalate), bensulide [O,O-diisopropyl phosphorodithioateS-ester withN-(2-mercaptoethyl)benzenesulfonamide], and oxadiazon [2-tert-butyl-4(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one] were applied to bermudagrass [Cynodon dactylon(L.) Pers. ‘Common′] as consecutive repeated annual treatments or in all possible sequence combinations for 3 yr to determine the effects on species composition of winter and summer annual weeds. Regardless of the rotation of treatments on winter weeds, oxadiazon increased the cover of common chickweed [Stellaria media(L.) Cyrillo], spur weed (Solivaspp.), and thymeleaf sandwort (Arenaria serpyllifoliaL.); bensulide increased the cover of corn speedwell (Veronica arvensisL.); and DCPA in most instances increased the cover of hop clover (Trifolium agrariumL.) and spur weed. When a herbicide controlled large crabgrass [Digitaria sanguinalis(L.) Scop.] or goosegrass (Eleusine indicaL. Gaertn.), the cover of weeds not controlled increased rapidly, with the exception of oxadiazon applied for 3 consecutive yr.