Economic Returns from Broadleaf Weed Control in Hard Red Winter Wheat (Triticum aestivum)

Abstract

Seventeen on-farm and two experiment station experiments were conducted to evaluate farmers' decisions to apply broadleaf weed control herbicides to tillered hard red winter wheat in February or March with or without urea-ammonium nitrate (28-0-0) fertilizer carrier. The herbicides and rates varied by farm, but all farmers applied a residual sulfonylurea herbicide and four added a phenoxy herbicide. Most farmer-selected herbicide treatments controlled target weeds including bushy wallflower, flixweed, henbit, plains coreopsis, smallflowered bittercress, and wild buckwheat. Controlling these weeds increased wheat yield on only two farms. Farmer-selected, commercially applied treatments increased net returns at two of seventeen farms, decreased net returns at seven farms, and did not affect returns at eight farms. Net returns were increased over the farmer-selected treatments at two farms when half the farmer-selected rate of herbicide was used. Half-rate herbicide treatments controlled weeds up to 25% less than farmer-selected treatments. Weed control with the half-rate treatments ranged from 60 to 98%. None of the farmers expected that herbicide use would increase yield. Their primary objective was to have weed-free fields at harvest. Nitrogen rates appeared to be selected without a rational basis for decision making.