向日葵黑斑病是一种流行性叶斑病,一般年份病指在70左右,可减产10—20％,大流行年份病指在95以上,减产50％左右。本文研究了该病的初侵染源及流行规律,试验表明:向日葵黑斑病的流行曲线呈S型。病害流行主要受湿度、降雨量及其频度影响。特别是7月至8月10日降雨量超过185mm,r≥80％,同时t≥20℃的天数在14d以上,病害普遍流行,湿度低于90％不发病或不表现症状。 Sunflower black spot disease is a kind of epidemic leaf spot disease, the general year sickness index is around 70, may cut 10-20%, the disease year of the pandemic year is above 95, reduces 50% about. In this paper, the initial source of infection and epidemic law of the disease were studied. The results showed that the epidemic curve of sunflower black spot was S-shaped. Epidemics are mainly affected by humidity, rainfall and frequency. Especially the rainfall from July to August 10 is more than 185mm, r≥80%, while the number of days with t ≥20 ℃ is above 14d, the diseases are common and the humidity is less than 90%, with no disease or no symptoms.