小麦白粉病为间隙性流行病害,在3月底4月初发病,病害流行主要与品种、温度、湿度、肥料和地理环境有关。气温上升到10℃以上进入普遍上升期,气温达14～15℃以后,发病率明显上升。病害发生需要70%以上的相对湿度,湿度愈高,对病菌侵染愈有利,但雨量大并连续降雨对病害发生不利,过程性降雨有利于病害的发生。白粉病在小麦各生育期均可发生,主要危害叶片,严重时也危害叶鞘、茎秆和穗 Wheat powdery mildew is a disease of intermittent epidemic which occurs in early March and early April. The prevalence of the disease is mainly related to variety, temperature, humidity, fertilizer and geographical environment. The temperature rose to above 10 ℃ into the general rising period, the temperature reached 14 ~ 15 ℃, the incidence increased significantly. Disease occurs more than 70% relative humidity, the higher the humidity, the more beneficial bacteria infection, but the rainfall is large and continuous rainfall adverse to disease, the process of rainfall is conducive to the occurrence of disease. Powdery mildew can occur in all growth stages of wheat, the main damage leaves, in severe cases also endanger leaf sheath, stem and ear