Disease law and forecasting of the needle blight ofPinus sylvestris var.mongolica

Fixed quadrates were established in different stands. In continued six years, the occurring period, occurring amounts and the relation between epidemic disease and environmental factors were investigated according to spraying laws of spores and accounting measures of disease ranking. The occuring peak period of the disease was from the last ten days of May to the second ten days of June. The epidemic period was from the last ten days of June to the second ten days of July and the initial decease period was from the last ten days of July to the beginning of September. The change of the disease depended on air temperature, relative humidity and precipitation. A multiple linear regression model was established using computer, which can predict the disease index(Y) of 10 days later, with more than 95% reliability (Responsible Editor: Chai Ruihai)