Broadleaf Weed Management in Grain Sorghum with Reduced Rates of Postemergence Herbicides1

2,4-D is the most widely used herbicide for weed control in grain sorghum in northern Tamaulipas, Mexico. Crop injury caused by 2,4-D drift to nontarget crops commonly occurs because of prevailing high winds. Field experiments were conducted from 2001 to 2003 to evaluate an integrated weed management program in grain sorghum with alternative postemergence herbicides to 2,4-D at registered and reduced rates. Bromoxynil applied at 480 (registered rate), 360, and 240 g/ha provided excellent broadleaf weed control when adequate rainfall occurred. Prosulfuron at 14.2 g/ha applied broadcast without cultivation provided excellent weed control and sorghum yield comparable with 28.5 g/ha (registered rate). This treatment represented a 32% cost reduction and 50% reduction in herbicide input compared with prosulfuron applied at registered rate without cultivation, and 31% cost reduction compared with 2,4-D at the registered rate (590 g ae/ha) plus cultivation, considered the commercial standard. Nomenclature: Bromoxynil; prosulfuron; 2,4-D; grain sorghum, Sorghum bicolor (L.) Moench. ‘Pioneer 82G63’. Additional index words: Integrated weed management, IWM. Abbreviations: POST, postemergence; WAT, weeks after treatment.