Selectivities of some turf herbicides between Broomsedge (Andropogon virginicus L.) and manilagrass (Zoysia matrella Merr.)

Abstract

Selectivites of 6 turf herbicides, asulam, propyzamide, trifloxysulfuron-sodium, metsulfuron-methyl, flazasulfuron and bispyribac sodium between manilagrass and 1–2 leaf stage from to 2 years old of broomsedge were evaluated by a pot test under greenhouse conditions. I₁₀ values and I₉₀ values are doses needed for 10% and 90% reduction in the turf and the weed shoot growth as compared to those of untreated controls, respectively. Selectivities (I₁₀/I₉₀) of all herbicides tested were decreased with an increase in the growth stage of the weed, and were less than 1.0 when the weed was 2 years old stage. Good selectivities (>1.0) were obtained from the treatment of asulam at 1–2 L and 5–6 L stages, trifroxysulfuron-sodium at 1–2 L, 5–6 L, and 10–12 L stages, metsulfruon-methyl at 1–2 L stage, flazasulfuron at 1–2 L stage and bispyribac-sodium at 1–2 L, 5–6 L and 10–12 L stages. In conclude, the results suggest that trifroxysulfuron-sodium and bispyribac-sodium are able to selectively control the broomsedge from 1–2 L to 10–12 L stages in Zoysia matrella turf.