Evaluation of the Efficacy of Azoxystrobin-Difnoconazole Fungicide (SC, 32.5%) in order to Control of Cercospors Leaf Spot in Sugar Beet

Cercospora leaf spot causes quantitative and qualitative damages to the sugar beet production in some provinces and testing new fungicides to control this disease is necessary. In this research, Ortivatop (azoxystrobin-difnoconazole SC 32.5%) fungicide was evaluated against the disease caused by Cercospora beticola in West Azerbaijan and Khuzestan provinces of Iran. Treatments included Ortiva top at three doses (1.25 1 and 0.75 l/hec), Carbendazim at 0.5 kg/hec and no fungicide control. The design of the experiments was randomized complete block design (RCBD) with five treatments and four replications. Fungicide application was performed after observation of the first symptoms of the disease as circular leaf spots. Disease evaluation was done in different treatments based on a 0-5 disease severity index scaling.  In addition to the disease, the yield of sugar beet root for each treatement was also determined at the harvesting time. According to the results, in West Azarbaijan province, Ortiva top at 1.25 and 1 l/h were the most effective treatments and reduced the disease severity by 80% and 70% respectively. With regard to the yield, Ortivatop at 1.25 and 1 l/h were also significantly effective and resulted in 55 and 43% increase in the yield respectively. In Khuzestan province, results indicated that all fungicides reduced the disease severity significantly and the most effective treatments were Ortivatop at 1.25 and 1 l/h with 82 and 75% disease reduction respectively. Regarding the yield, all three doses of Ortiva top were significantly effective and increased the yield by 44% compared to the control.