Integrating reduced rates of postemergence herbicides and cultivation for broadleaf weed control in sugarbeet ( Beta vulgaris L.)

Abstract. This experiment was conducted from 2002 to 2004 to determine the best weed control method and evaluate application of reduced rates of herbicides in sugarbeet at the Safi abad agricultural research center of Dezful and agricultural research station of Boroujerd , I. R. Iran. The experimental design was a randomized complete block design with strip plot arrangement of treatments with three replicates. Cultivation was as vertical factor at three levels consisting : reciprocal application of shovel and blade cultivator at 6 – 8 leaf stage of sugarbeet and repeating at reemergence of weeds , and uncultivated treatments . Herbicide application was as horizontal factor at eight levels consisting : application of chloridazon + phenmedipham at 4+5 and 3+4 Kg/L ha-1 , betanal progress A-M ( phenmedipham + desmedipham + ethofumesate ) at 3 and 4 L ha-1 at 4 – 6 leaf stage of sugarbeet , triflusulfuron at 20 and 30 g ha-1 at cotyledonous leaf stage of sugarbeet , weed free and weedy checks. In 2002 at Safi abad and Boroujerd chloridazon at 3+4 and 4+5 Kg/L ha-1 were the most effective treatments in controlling broadleaf weeds and had also the highest level of sugarbeet root yield after the weed free check. In 2003 at Safi abad betanal progress A-M at 4 L ha-1 was the most effective treatment in controlling broadleaf weeds but in Boroujerd there were not significant difference among herbicide treatments and chloridazon at 3+4 Kg/L ha-1 and triflusulfuron at 20 g ha-1 had the highest level of sugarbeet root yield after the weed free check at Safi abad and Boroujerd , respectively. Reciprocal application of shovel and blade cultivator compared to uncultivated plots increased sugarbeet root yield by 11 and 27% , respectively. According to this experiment application of each of the following herbicide treatments is recommended for weed control and sugarbeet yield increase : chloridazon at 3+4 and 4+5 Kg/L ha-1 , betanal progress A-M at 4 L ha-1 at 4-6 leaf stage of sugarbeet and triflusulfuron at 20 g ha-1 at cotyledonous leaf stage of sugarbeet in conjunction with the application of shovel or blade cultivator at 6-8 of shovel or blade cultivator at 6-8 leaf stage of sugarbeet and repeating at reemergence of weeds.