effects of hilling time and cover crop on weed control and potato yield

the recent decades emphasis on reducing pesticide use especially herbicide has led to increased interest in alternative weed control methods. the purpose of this study was to evaluate the hilling time and simultaneous interseeding of two cover crops as living mulch to control weeds in potato and to determine the impact of these actions on potato yield. a randomized complete block design as split plot with three replications was used with hilling time (two levels containing 3 and 5 weeks after potato planting) and cover crops (four levels containing barley, persian clover, no-cover and chemical control) as main and subplot treatments, respectively. the barley cover crop in the first hilling time was needed to control using sethoxydim (0.21 kg ai ha-1).weed and cover crop numbers were recorded three weeks after hilling time and their biomass was measured at harvest time. generally the hilling time had no effect on weed and cover crop numbers but was effective on their biomass so that the average weed biomass in second hilling time was less than its first but the cover crop biomass in second hilling time was more than its first because of controlling barley in first hilling time. barley cover crop was superior to persian clover in weed control and because of slow growth of persian clover, its weed biomass was as no-cover crop treatment. however the potato yields were highest with the chemical control but considering to hilling time and cover crop interaction on potato yield, the controlled barley in the first hilling time was to able to provide yields comparable to chemical control. thus the results suggest that early interseeding of barley as cover crop supplemented with a postemergence narrow leaves herbicide may both control weed adequately with less herbicide and provide yields comparable with conventional potato production systems.