Volunteer wheat (Triticum aestivum L.) competition in corn (Zea mays L.)

Volunteer winter wheat (Triticum aestivum L.) is a sporadic weed found in corn (Zea mays L.) fields across southern Ontario. Eight trials were conducted over a 2-yr period (2006 and 2007) at four locations to determine the competitiveness of volunteer winter wheat in corn. A soft red winter wheat cultivar (Pioneer 25R47) was seeded at each location at densities of 0 to 30 seeds m-2 late in the fall, prior to corn planting the following spring. Volunteer wheat competition in corn resulted in reduced emergence of corn leaf collars. Competition with volunteer wheat resulted in a 5% decrease in corn leaf collars present at 21 and 70 d after emergence with volunteer wheat densities of 3.0 and 5.2 plants m-2, respectively. Furthermore, volunteer wheat competition reduced total leaf area, leaf dry weight, shoot dry weight, plant and ear height and yield by 5% with densities of 5.1 to 6.0 plants m-2 compared with the weed-free control. The level of competitiveness was dependent on the density of volunteer wheat.