Profitable, Effective Herbicides for Planting-Time Weed Control in No-till Spring Wheat (Triticum aestivum)

High herbicide costs and uncertainty about annual weed control at planting have limited adoption of no-till spring wheat production systems in the northern Great Plains. Chlorsulfuron, metsulfuron, and CGA-131036 at 10 to 20 g ai ha–1 plus nonionic surfactant generally controlled both emerged kochia and wild mustard equally well (>80%) whether or not combined with glyphosate at 250 g ha–1 plus nonionic surfactant. In two of three trials persistent phytotoxic residues of these sulfonylurea herbicides in soil controlled both weeds better in midseason and early summer 1 yr after treatment than did glyphosate, which has only foliar activity. While the absolute net returns of different treatments varied among herbicides, relative net returns were insensitive to changes in either herbicide or wheat price. Herbicide use tended to boost net returns for no-till spring wheat in years with good weather but depressed net returns in a drought year. Chlorsulfuron at 10 and 20 g ha–1 increased net returns in all three trials. Metsulfuron and combinations of either metsulfuron or chlorsulfuron with glyphosate had variable effects on net returns.