Abstract:

To determine the occurrence rule and prediction model, the field dynamic of cucumber powdery mildew under protected cultivation in Hangzhou during the years from 2007 to 2019 was investigated. The results showed that the peak period of the disease occurrence was very similar among different years. The powdery mildew severity in spring cucumber reached the highest peak in the middle ten days of June, while the occurrence of the disease would reach the peak in early October for autumn cucumber. There were significant differences in the peak duration and quantity of cucumber powdery mildew among years. The disease of spring and autumn cucumber led to peak quantities in 2019 and 2009, respectively. It was an unusual year in 2013 that the disease was found to be serious both in spring and autumn but short in the peak duration. In addition, it was found that the field dynamic of cucumber powdery mildew was closely related to the climate condition. For example, the disease would break out if the air temperature or environmental humidity exchanged frequently. Based on the monitoring data including the disease index of powdery mildew and climate factors from March to October every year, the prediction mathematical models of occurrence quantity for the disease in spring and autumn cucumber were established using the method of stepwise regression. Testing of the prediction accuracy of these models showed that the predicted values were consistent with the measured values and the scores representing prediction accuracy were over 75. Thus, these models could accurately predict the degree of occurrence for cucurbit powdery mildew.

Key words: protected cultivation, cucumber powdery mildew, epidemic dynamic, occurrence amount, prediction model