Crop rotation is one of the most traditional and sustainable techniques in weed management in a way that a proper rotation could diminishes a majority of problematic weeds. In order to assess the response of weeds to a number of different rotations, a study was carried out on a six-year experiment which was arranged based on a randomized complete block design with four replications at Agricultural Research Station of Khorasan Razavi, in Northeastern of Iran. In this study crop rotations included: vetch-potato, canola-potato, barley-potato and fallow-potato. Each rotation was repeated three times during the 6-year course of the experiment. The dominant weed species were spring annual plants including common lambsquarters (Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.). Barley-potato rotation significantly reduced weeds populations. In fallow-potato rotation the highest density of perennial weeds was observed. Canola-potato rotation proved highly successful in controlling weeds during the growing season and potato yield in this rotation was the greatest compare to other rotations. Canola had a drastic potential of weed suppression, and it can reduce weed density and dry matters if located in the crop rotations.
