Abstract: The rice blast disease epidemics are closely related with the cultivated rice varieties, genetic diversity of Magnaporthe grisea and climate. Therefore, monitoring and analyzing the impacts of cultivated rice varieties and climate factors on rice blast disease will provide valuable information for rice blast control. By investigating rice blast disease on main cultivated rice varieties within Hangzhou city, we found great differences in both rice varieties and farming area during 2015-2016 year. Remarkably, Japonica rice was more susceptible to blast than indica rice. Second, the dominant japonica rice including Zhejing 88 was highly infested by rice blast in plain area. Furthermore, rice blast continuously occurred in indica rice as Zhongzheyou 1 in the eastern mountain area with high moisture and lack of sunlight. Last, rice blast severely happened at large area with multiple rice varieties in 2015, but was moderate in 2016. Based on the rice blast monitoring and climate data during 2011-2015, we mathematically analyzed the correlation between epidemic and climate factors, and modelled the correlation between epidemic and grain lost. Our results showed strong correlation among epidemic, grain lost and climate factors such as temperature, moisture, rainfall, sunlight, which had been verified to be reliable models and could be further used for the prediction of rice blast epidemic. This study suggested that adjusting rice varieties structure according to the rice blast monitoring data together with the proper prevention approaches responding to climate conditions was a useful tool for the sustainable control of rice blast disease.

Key words: rice blast disease, cultivated rice varieties, susceptibility, climate factors, correlation analysis