Herbicidal Phytotoxicity to Emerald Zoysia during Establishment

Abstract

A study of herbicides to aid in establishing an Emerald zoysia (Zoysia japonica x Zoysia tenuifolia Willd. ex Trin.) sod was initiated in the summer of 1965. Eleven herbicides were applied to Emerald zoysia sod-plugs newly planted in Emory clay loam soil. All of the herbicides provided excellent premergence control of crabgrass (Digitaria spp.) and goosegrass (Eleusine indica (L.) Gaertn.) throughout the growing season following treatments. Both 1-(2-methylcyclohexyl)-3-phenylurea (siduron) and O-(2,4-dichlorophenyl) O-methyl isopropylphosphoramido-thioate (DMPA) caused either no observable injury or only slight injury, thus causing no apparent chemical inhibition of growth and resulting in a rapid rate of establishment of the turfgrass. But N-(2-mercaptoethyl)benzenesulfonamide S-(O,O-diisopropyl phosphorodithioate) (bensulide) and 2,6-di-tert-p-tolyl-methylcarbamate (terbutol) severely injured Emerald zoysia; they seriously retarded the growth of the zoysia and greatly inhibited ground cover. Herbicides which effectively eliminated weed competition but which greatly retarded the growth of the turfgrass were more detrimental to establishment rate than the actual competition from weeds. These results indicate that selecting a herbicide safe to the turfgrass is more important than choosing a herbicide which only gives good weed control. However, indications are that some herbicides do combine the two important factors of safety and excellent weed control.