Influence of propaquizafop application rate and time on Sorghum halepense (L.) Pers. control and cotton (Gossypium hirsutum) yield

Field experiments were carried out from 1990 through 1992 to study the effect of propaquizafop application rate and application timing of fluazifop, haloxyfop, propaquizafop, quizalofop, and hoeing on Sorghum halepense (L.) Pers. control and seed cotton yield. Control of S. halepense with propaquizafop applied to plants 20–35 cm tall was not affected by rate of application and was similar to that obtained with fluazifop applied at the recommended rate. Cotton yield following all herbicide treatments was greater than that of the weedy control, but lower than that of the weedfree control. S. halepense control with fluazifop, haloxyfop, propaquizafop, and quizalofop applied to plants 20–35 or 35–80 cm tall was greater than that obtained with their application to plants 5–15 or 10–25 cm tall. Ho-eing, applied once at any S. halepense growth stage, provided less control than any herbicide treatment on the same date. Cotton yield was increased by all herbicide treatments and hoeing compared to that of the weedy control, but the highest yield was obtained after herbicide appli-cation to S. halepense plants 10–25 cm tall. However, none of the herbicide treatments or hoeing increased cotton yield to the level of the weedfree control.