Integrated weed control of sugar beet in the method of complete seedbed preparation in autumn

A field experiment was carried out during 2003-2004 growing season at research field of Sugar Beet Seed Institute (SBSI) in Karaj, to study the integrated post-emergence weed control methods in the system of sugar beet seedbed preparation in autumn. The experimental design was split-split plot based on a randomized complete block design with four replications. The main plots consisted of using and non-using cultivation for weed control at eight leaf stage of sugar beet and the sub plots of nine post emergence herbicide, the sub-sub plots of hoeing and no hoeing in their thinning stage. Plant population of weed species was determined before and after herbicide application and their dry weights at harvest time. The results in the system of sugar beet seedbed preparation in autumn indicated that hoeing in the thinning stage of sugar beet was not affected on the post emergence weeds, presumably due to winter weeds residue on the soil surface as mulch. Among the herbicides, split application of the Triflusulfuron + Phenmedipham+Desmedipham+Ethofumesate and also the Cloridazon + Phenmedipham+Desmedipham+Ethofumesate both had the most efficiency in controlling the post-emergence weeds. Thus, they can be considering as the most effective sugar beet herbicides. In the method of complete seedbed preparation in autumn, when sugar beet canopy catches good ground cover, cultivating at eight leaf stage of sugar beet will not control significantly post emergence weeds.