Trellised plants of `Oregon Sugar Pod II' and `Snowflake' snow peas (Pisum sativum var. macrocarpon Ser.) were grown in single and double rows on l-m centers at a constant population of 20 plants/m2 in 1988 and 1990. Plants of `Oregon Sugar Pod II' produced a greater number and weight of fresh pods than plants of `Snowflake' in both years. Plants grown in double rows (10 cm within-row spacing) produced a greater number and weight of fresh pods than plants grown in single rows (5 cm within-row spacing) in 1988, but not in 1990. Vine dry weights were greater from plants grown in double rows than from plants grown in single rows in both years. Double rows seemed more promising for home gardeners than for commercial growers because of the increased branching and more widely scattered pod distribution on plants grown in double rows compared with plants grown in single rows.
Brian A. Kahn and Wendy A. Nelson
Orion P. Grimmer and John B. Masiunas
Winter-killed cover crops may protect the soil surface from erosion and reduce herbicide use in an early planted crop such as pea (Pisum sativum). Our objective was to determine the potential of winter-killed cover crops in a snap pea production system. White mustard (Brassica hirta) produced the most residue in the fall but retained only 37% of that residue into the spring. Barley (Hordeum vulgare) and oats (Avena sativa) produced less fall residue but had more residue and ground cover in the spring. Greater ground cover in the spring facilitated higher soil moisture, contributing to higher weed numbers and weight and lower pea yields for oat and barley compared with a bare ground treatment. White mustard had weed populations and pea yields similar to the bare ground treatment. Within the weed-free subplot, no differences in pea yields existed among cover crop treatments, indicating no direct interference with pea growth by the residues. In greenhouse experiments, field-grown oat and barley residue suppressed greater than 50% of the germination of common lambsquarters (Chenopodium album) and shepherd's-purse (Capsella bursapastoris), while in the field none of the cover crop provided better weed control than the fallow.
Timothy Coolong, Derek M. Law, John C. Snyder, Brent Rowell, and Mark A. Williams
broccoli ( Brassica oleracea italica group), sweet corn ( Zea mays ), tomato [ Solanum lycopersicum (synonym Lycopersicon esculentum )], bell pepper ( Capsicum annuum ), winter squash ( Cucurbita sp.), and snap pea ( Pisum sativum var. macrocarpon