The majority of dry pea (pea) cultivars in current production have semileafless architecture. Although these cultivars tend to yield well and resist lodging, they may not be the best cultivars in terms of competition with weeds. Experiments were conducted at Lacombe and Lethbridge, Alberta, Canada, from 2003 to 2005 to compare semileafless and leafy pea cultivars under different seeding and herbicide regimes. During the study, in terms of weed emergence and biomass, oat (seeded) was usually more dominant than broadleaf weeds. Higher-disturbance sweep seeding led to slightly greater oat populations than lower disturbance seeding with knives. Leafy pea had lower yield potential in less weedy conditions than the semileafless pea, but the former were less susceptible to yield reduction as weed competition increased. Leafy pea often led to lower weed biomass and dockage than the semileafless pea. However, because semileafless pea yield at least as well as leafy pea in all of the environments encountered in this study, integrated weed management principles are currently best served by growing semileafless pea. Breeding to improve leafy cultivar yield potential may lead to greater opportunities for integrated weed management and herbicide input reductions in the future.

Nomenclature: Imazamox, imazethapyr, dry pea, Pisum sativum L., oat, Avena sativa L