INTEGRATION OF WEED MANAGEMENT AND TILLAGE PRACTICES IN SPRING DRY PEA PRODUCTION

Information about long-term efficient production systems is needed to assist growers in adopting conservation cropping practices for spring dry pea (Pisum sativum L.), a biologically important pulse crop grown in the Pacific Northwest and Canada. From 1985 to 1991, an integrated pest management field study examined the influence of three weed manag ement levels and two tillage regimes on the productivity of spring pea grown in a winter wheat (Triticum aestivum L.)-spring barley (Hordeum vulgare L.)-spring pea rotation. When averaged over 6 yr, spring pea yielded the least with the minimum weed management level in either the conservation (chisel plow) or conventional (moldboard plow) tillage s ystem. In conservation tillage, yields were similar at the moderate an d maximum weed management levels and up to 335 kg ha-1 more than pea w ith the minimum weed management level. In contrast, in conventional ti llage, yields were increased only at the maximum level of control comp ared with the minimum level. Yields of pea grown under conservation ti llage were equal to or greater than yields in conventional tillage whe n averaged over weed management levels. The reduced tillage system on the integrated pest management project met conservation compliance for both planting pea into spring barley residue and planting winter whea t into pea residue. In addition to reducing erosion, the conservation pea production system did not increase substantially herbicide use and cost, thus maintaining environmental quality.