Agronomic evaluation of mechanical and chemical weed management for reducing use of herbicides in single vs. twin-row sugarbeet

Field experiment was conducted at Iranian Plant Protection Research Farm at Karaj in 2009 to evaluate the effects of planting patterns, times of mechanical control and herbicides application on weeds in sugarbeet. Treatments were arranged as a split-split plot within a randomized complete block design (RCBD) with four replications. Three planting patterns considered as main-plot [(including single row spaced 50 cm, single row spaced 60 cm and twin row spaced 60 cm), three times of mechanical control as sub-plot (including mechanical weed control at 4-6, 10-12 and 14-16 leaves stage of sugarbeet) and two herbicides as sub-sub-plot (including metamitron+(phenmedipham+desmedipham+ethofumesat) and triflusulfuron-methil+(phenmedipham+desmedipham+ethofumesat)]. Results indicated significant effects of times of mechanical control and herbicie on weed density and biomass (Chenopodium album and Amaranthus retroflexus). In addition, machanical weed control at 4-6 leaves stage of sugarbeet caused the most reduction in biomass of Datura stramonium. Planting pattern had only significant effect on biomass and density of C. album. Furthermore, approximately all of treatments had significant effects on root yield, but approximately other sugarbeet components were not affected by treatments as appropriate as sugar yield. Totally, best results were achieved in metamitron+(phenmedipham+desmedipham+ethofumesat) and weed control at 4-6 leaves stage that had the most reduction in weeds density and biomass.