Epidemiology and Aerobiology of Pseudoperonospora cubensis in northwest Iran

This study was aimed at evaluating climatic variables and concentrations of airborne sporangia of Pseudoperonospora cubensis, the causal agent of cucumber downy mildew and its relation with the severity of the disease. Monitoring was conducted in a cucumber field located in Marand, Iran during 2014-2015. The aerial concentration of sporangia was evaluated by a whirling arm trap and the weather parameters were monitored using a local meteorological station. Statistical analysis indicated a significant correlation between disease severity and some climatic factors (P?0.05). The results showed that evaluation of airborne sporangia and the use of forecasting models could reduce the risk of disease in the northwest of Iran. The factorial analysis of the climate variables resulted in the development of two factors, average humidity and rain, that could be used as predictor variables in linear regression models for the downy mildew.