Cover Crops and their Effects of Time Harvesting on the Control of Weed in Citrus Orchards in Northern Iran

Weed are one of the most important problems in newly established orchards.Weed compete with young trees of citrus trees can reduce the growth. In order to investigation of effect of cover crops (Vicia sativa L. and Trifoliumalexandrinum L.) to control weed in citrus orchards in northern Iran, This studywas conducted by randomized complete block design with thirteen treatment and three replication (8 treatments of the two cover crop with different harvest times, two treatments of herbicide, plowing and weeding and treatment of control). The results of this study showed, berseem clover to common vetch has better performance in reduced weed . There was a noticeable decrease of dry and wet weight and density of weed in harvest and drop off residuesof berseem clover on fifth of April.spring is the best time to harvest it. When we use common vetch as a cover crop, the best time to harvesting is the middle spring.