Factors Influencing Control of Annual Grasses with Sethoxydim or RO-13-8895

Abstract

Studies were conducted to measure the foliar activity of sethoxydim (BAS 9052 OH) {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl-3-hydroxy-2-cyclohexen-1-one} and RO-13-8895 {acetone-O-[D-2-[p-[(α,α,α-trifluoro-p-tolyl)-oxy] phenoxy] propionyl] oxime} as affected by adjuvants, soil moisture, and growth stage of grasses, and to compare the responses of three grass species to these herbicides. The activity of both herbicides was increased by adjuvants. The activity of sethoxydim was not significantly affected by soil moisture. Goosegrass [Eleusine indica(L.) Gaertn. ♯3ELEIN] and broadleaf signalgrass [Brachiaria platyphylla(Griseb. ♯ BRAPP) Nash] control was greater with RO-13-8895 at the high than at the low soil moisture level. Soil moisture did not influence large crabgrass [Digitaria sanguinalis(L.) Scop. ♯ DIGSA] control, since it was relatively tolerant to RO-13-8895. Both herbicides gave greater control at early than at late growth stages. When averaged over all variables, sethoxydim gave greater large crabgrass control than RO-13-8895, but RO-13-8895 gave greater goosegrass and broadleaf signalgrass control than sethoxydim.