Green Foxtail (Setaria viridis) Competition with Spring Wheat (Triticum aestivum)
Yield reductions due to green foxtail competition with hard red spring wheat varied with environment in field experiments conducted in 1984, 1985, and 1986 at Oakes, Langdon, Prosper, and Fargo, North Dakota. Wheat yield reductions ranged from 0 to 47% from 720 green foxtail plants per m2. Inclusion of early season temperature and precipitation, soil texture, and foxtail density into multiple regression analysis of wheat yield reductions significantly increased the coefficient of determination to 0.62 compared with 0.12 for regression based on green foxtail density alone. Wheat yield reduction decreased as green foxtail seeding was delayed after wheat seeding in 1986. Wheat yield generally decreased as time of diclofop application was delayed from 2 to 6 wk after wheat emergence in 1986.