Efficacy of mixing common herbicides in control of broadleaf weeds in sugar beet (Beta vulgaris L.)

In order to evaluate the mixing efficiency of desmedipham (7.1%) phenmedipham (9.1%) ethofumesate (11.2%) with Betanal Progress-OF®, chloridazon and clopyralid (control) in controlling purslane (Portulaca oleracea L.), black nightshade (Solanum nigrum L.), redroot pigweed (Amaranthus retroflexus L.) and common lambsquarters (Chenopodium album L.) in sugar beet fields, an experiment was conducted in a randomized complete block design (RCBD) with 54 treatments and three replications at Research Field of Faculty of Agriculture of Ferdowsi University, Mashhad, Iran in 2014. The treatments consisted of separate application and mixture of the above-mentioned herbicides with five mixing ratios including 100:0, 75:25, 50:50, 25:75 and 0:100. Results showed that application of desmedipham phenmedipham ethofumesate in separate and in different mixtures could efficiently control the purslane and black nightshade weeds. Separate application of chloridazon or clopyralid and also in mixtures in which the above-mentioned herbicides had a higher ratio had a lower efficiency in reducing the biomass of weeds. The efficiency of different herbicides in the control of redroot pigweed and common lambsquarters was less than purslane and black nightshade and it seems that these two weeds are more able to survive when exposure to herbicides. The highest (39.88 t ha-1) and lowest (36.98 t ha-1) root yield of sugar beet in each plot of chloridazon and clopyralid was observed in 50:50 ratio of desmedipham phenmedipham ethofumesate mixture and clopyralid alone, respectively. No significant effect of herbicide application on sugar beet damage was observed and sugar beet plants were able to compensate for the damage. Therefore, it can be said that the mixture of herbicides inhibiting photosynthesis and lipid synthesis with other herbicide groups not only increase the efficiency of these treatments but also prevents the yield reduction and occurrence of herbicide resistance in sugar beet fields.