Document Type : Research Article
An experiment was conducted to evaluate the efficacy of clopyralid mixed with other herbicides weeds and sugar beet (Beta vulgaris) in 2008 at experimental field of research center of agricultural and natural resources research center of Khorasan Razavi. Experimental design was completely randomized block with three replications. Treatment were included doses of 350 and 500 ml.ha-1 Clopyralid in combination with phenmedipham (5000 ml.ha-1), phenmedipham+ desmedipham+ ethofumesate (4000 ml.ha-1), chloridazon (4000 g.ha-1), metamitron (4000 g.ha-1), triflusulfuron-methyl (60 g.ha-1), haloxyphop-R-methyl (750 ml.ha-1) and sethoxydim (2500 ml.ha-1) along with full season hand weeding. Results showed that at the dose of 500 ml.ha-1 in mixed with 300 ml.ha-1 clopyralid had best weed control. Rate of 500 ml.ha-1 clopyralid in Combination by phenmedipham, phenmedipham +desmedipham+ ethofumesate and chloridazon without significant difference were best control treatments. However phenmedipham had lowest toxicity since combination of this herbicide at dose of 500 ml.ha-1 clopyralid was suggested with regard to ecological and economic aspect. The combination of 500 ml.ha-1 clopyralid with haloxyphop-R-methyl and Sethoxydim were best treatments to control grasses, specifically Cynodon dactylon. Maximum root yield were obtained at combination of clopyralid dose of 500 ml.ha-1 with chloridazon, haloxyphop-R-methyl, phenmedipham+desmedipham+ethofumesate, phenmedipham, and sethoxydim. A linear relationship was observed between sugar beet root yield and percentage of weed control.