WILD MUSTARD (SINAPIS-ARVENSIS) RESPONSE TO FIELD PEA (PISUM-SATIVUM)CULTIVAR AND SEEDING RATE

Field studies were conducted at Morden, Manitoba from 1992 to 1995 and Wadena, Saskatchewan in 1995 to investigate the effect of cultivar se lection and seeding rate on field pea competitiveness with wild mustar d. Cultivars that had both long Vines and rapid canopy development (le af area index) were more competitive with wild mustard than those with short vines and slow canopy development. Cultivars differed markedly in their ability to suppress weed growth. Wild mustard density was aff ected in 2 of 4 yr by cultivar selection, while weed biomass was affec ted in 3 of 4 yr. Field pea yield losses under weedy conditions differ ed among cultivars and those cultivars that more effectively reduced w ild mustard density or biomass had the lowest yield losses. Yield loss es from wild mustard competition did not differ among cultivars when w eed pressure was high and weeds emerged 1 wk before the crop. Seeding rate of Titan, a cultivar with long vine length, affected wild mustard biomass more than Trump, a cultivar with a short vine length.