A Sustainable Management Package to Improve Winter Wheat Production and Competition with Weeds

Advances in cultivar development and the demand for winter wheat (Triticum aestivum L.) as an ethanol feedstock has increased winter wheat acreage across the Canadian Prairies. A sustainable production package is required to maintain this renewed interest. Experiments were established in 2002-2004 at Lethbridge and Lacombe, AB, to determine cultivar, seeding rate, and herbicide effects on weed competition and crop yield. Treatments included a factorial combination of four contrasting cultivars (Radiant, CDC Osprey, CDC Falcon, and CDC Ptarmigan), three seeding rates (300, 450, and 600 seeds m(-2)), and two herbicide treatments (fall only or fall plus a spring in-crop herbicide). CDC Ptarmigan yield was higher (12%) than the other cultivars. This was expected as CDC Ptarmigan has higher yield potential, but its ability to maintain high yields in the presence of weeds was unexpected. The yield of CDC Falcon and Radiant was similar, but CDC Falcon had inferior weed competitive ability, as shown by yield differences, relative to the other three cultivars. CDC Osprey yielded less than the other cultivars. Grain yield was reduced when planted at 600 seeds m(-2) by 4%, but weed biomass was less (40%). Spring in-crop herbicide application reduced weed biomass, but the extra application did not improve grain yield. These results suggest winter wheat yields can be maintained without added inputs of spring herbicides, and greater stability of yield, winter survival, and competitiveness will usually occur with increased seeding rates.