Evaluation of efficacy of Aliado and Cyazofamid fungicides against downy mildew of local and commercial cucumber in Guilan

Downy mildew is one of the most important foliar disease of field and greenhouse cultivated cucumber which caused by the Pseudoperonospora cubensis and engender significant economic damages in Iran annually. The effect of ALIADO with dose rates of 1, 2, and 3 g/l and Cyazofamid (Ranman® SC 400) at the rate of 0.5 ml/l on the control of the disease was assessed on local (susceptible) and commercial (very susceptible) cultivars in the field condition. The experiment was done in randomized complete block design with 4 replication (local cultivar) and 3 replication (PS cultivar), in Kiashahr which has a history of cucumber cultivation and downy mildew disease occurrence. Spraying was carried out immediately after the appearance of disease symptoms and was repeated at intervals of 10, 7 and 5 days. For evaluation of each treatment, data was recorded based on disease severity on the leaves from 4 plants in each plot after 10, 7 and 5 days of fungicides application. Data collected were analyzed by SPSS software and Tukey test. Results showed that fungicide application caused significant decrease in the disease severity compared with the control treatment. The disease control rates were 89.3%, 85.8% and 79.7% on the local cultivar and 86/1%, 85.1% and 77.79% on the commercial cultivar in Cyazofamid and ALIADO with dose rates 3 and 2g/l respectively after the last spraying.