Field experiments were conducted in Oklahoma to quantify the wheat grain yield losses and price discounts resulting from season-long interference with cheat, feral rye, Italian ryegrass, jointed goatgrass, and wild oat. Plots were seeded to individual weeds at one of seven seeding rates, and wheat was planted in all plots at a uniform rate. Maximum weed densities were 89 (cheat), 80 (feral rye), 158 (Italian ryegrass), 170 (jointed goatgrass), and 120 plants/m2 (wild oat). Wheat grain yield losses caused by interference from the maximum density of each weed species were 19 (cheat), 55 (feral rye), 20 (Italian ryegrass), 21 (jointed goatgrass), and 28% (wild oat). Wheat grain total price discounts caused by interference from the maximum density of each weed species were 22 (cheat), 368 (feral rye), 26 (Italian ryegrass), 36 (jointed goatgrass), and 64 cents/hectoliter (wild oat). Of the five weed species included in this research, interference from feral rye had the greatest effect on wheat grain yield and price.
Nomenclature: Cheat, Bromus secalinus L. BROSE; feral rye, Secale cereale L. SECCE; Italian ryegrass, Lolium perenne L. ssp. multiflorum (Lam.) Husnot LOLMU; jointed goatgrass, Aegilops cylindrica Host AEGCY; wild oat, Avena fatua L. AVEFA; wheat, Triticum aestivum L. ‘Jagger’.