Evaluation of the Efficacy of spiroxamine (CS 300) for Chemical Control of Grapevine Powdery Mildew in Comparison with Some other Fungicides

Grape powdery mildew caused by Erysiphe necator Schwein is one of the most important diseases of grapevine in many countries including Iran. In this study, the efficacy of the new fungicide, Prosper® (Spiroxamine), was compared with the registered fungicides Belkute® (Iminoctadine Tris), Topas® (Penconazole), Stroby® (Kresoxim-methyl) and sulfur for the control of grape powdery mildew. The experiment was carried out in three provinces including Fars, Razavi-Khorasan and Isfahan in randomized complete block design with nine treatments and four replicates. Each replicate contained two seven year old grapevine trees. The first spraying was performed just as the buds started to open and the second spraying was performed 15 days later. Prosper® was used in different doses for the first and second spraying as follow:  0.35 and 0.6 ml L-1 for the first treatment, 0.7 and 1.2 ml L-1 for the second treatment, 1 and 1.8 ml L-1 for the third treatment.  Forty five days after the second spraying, 100 leaves and 8 bunches of grapes were selected randomly from each replicate and symptoms were recorded. The disease incidence and severity was calculated for all samples. The results show that Prosper® in doses of 0.7 and 1.2 ml L-1 after  the first and second spraying reduced the disease severity on grape leaves and fruits by 88.42% and 78.31% in Fars, 75.64% and 85.22% in Razavi-Khorasan and 36.73% and 61.07% in Isfahan compared with the control respectively. Therefore it could be concluded that Prosper can be used effectively to control grapevine powdery mildew in Iran.