eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2016-05-06 8 2 539 548 9416 article Keivan Saeb 1 SeifolahTaleghani 2 RaziehJafariHajati 3 Mohammad H. Fotokian 4 Department of Environment, Tonekabon Branch, Islamic Azad University, Tonekabon (Iran). M.S.C in plant biology, Islamic Azad University- Tonekabon Branch (Iran). Affiliated to the Young Researchers Club of the Tonekabon Branch, Islamic Azad University, Tonekabon (Iran). Department of Medicinal Plant Research Center, Shahed University, Tehran (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. https://www.biotech-asia.org/vol8no2/cover-crops-and-their-effects-of-time-harvesting-on-the-control-of-weed-in-citrus-orchards-in-northern-iran/ Cover crops; Weed; Berseem clover; Common vetch