Selected herbicide treatments from 25 winter annual broadleaf weed control experiments conducted across Oklahoma from 1979 to 1993 were examined for winter wheat yield response to weed control. All experiments contained one or two of the same three weeds (henbit, bushy wallflower, or cutleaf eveningprimrose) as the primary target(s). Herbicide treatments included chlorsulfuron at 8.8 or 17.6 g ai/ha, and/or 2,4-D at 420 g ae/ha, all broadcast POST to wheat. Most herbicide treatments controlled the weeds, but increased wheat grain yield at only one site, wherein bushy wallflower density was 830/m2. Correlation analysis found no relationship between weed densities and wheat yield when chlorsulfuron at 8.8 g/ha was applied for henbit or moderate levels of bushy wallflower or cutleaf eveningprimrose. There was a significant positive relationship favoring spraying of bushy wallflower when the correlation analysis included data from one site with a density of 830 plants/m2.
Examination of Winter Wheat Yield Response to Seed Source