Evaluation of the Efficacy of Belkute WP 40% against Erysiphenecator, the Causal Organism of Grape Powdery Mildew Disease

Powdery mildew disease caused by Erysiphe necatoris one of the most important diseases of vine that cause quality and quantity damage in many parts of Iran every year. In the present study, the efficacy of new fungicide, imonoctadin (Belkute® WP 40%) was compared with common fungicides including penconazole (Topas EW® 20%), sulfur (Kumulus-S® WP 80%), and sulfur powder for the control of Powdery mildew disease on grape. The experiment was carried out in Semnan (Shahrood), Kohkiloye and Boveirahmad (Yasuj) and Qazvin provinces in a Randomized Complete Block Design (RCBD) with 8 treatments and 4 replications. Treatments included Belkute at 0.5, 0.75 and 1 g/l, Topas 0.125 g/l, Kumulus –S 3 g/l, sulfur powder 60 – 90 kg per/ha. (According to the first, second and third stages of spraying) and controls (without any spraying and with water spraying). Treatments were applied at three stages (the first spraying time was before swelling buds, second one was after petal fall and the third one was 2-3 weeks after the second spraying, which coincided with the appearance of sour grapes). Percent disease incidence and Percent disease severity were measured and analyzed using SAS software in three provinces. Mean comparison of disease severity and disease incidence percentages were done by Duncan's multiple range test (α =5%). Results show significant differences between all the fungicide treatments and the controls. Belkute at 1and 0.75 g/l alone or in alternation with Topas 0.125 g/l had better controlling affects than the other treatments. Percent disease severity (PDS) in vines treated with Belkute 1and 0.75 g/l were 6.95 and 6.72% on leaves and 29.99 and 33.33% on fruits in Semnan Province, 10.40 and 2.45% on leaves and 3.30% on fruits in both treatments in Kohkiloye and Boveirahmad Province, 9.56 and 29.56% on leaves in Qazvin Province respectively. Also, percent disease incidence (PDI), were 30.50 and 37.50% on leaves and 70.00% on fruits in both treatments in Semnan Province, 7.75 and 10.50% on leaves and 10.00% on fruits in both treatments in Kohkiloye and Boveirahmad Province, 42.75 and 50.86% on leaves and 85.00 and 70.00% on fruits in Qazvin Province respectively.