通过对小麦白粉菌有性时期形成、发育进度及在不同条件下病菌对自生麦苗侵染的观察研究 ,结果表明 :小麦白粉菌有性时期在小麦孕穗期开始出现 ,在不同感病品种上出现的迟早和形成量的多少有很大差异。闭囊壳在正常年份不能与秋苗形成菌源衔接 ,只侵染自生麦苗 ,在整个侵染循环中起着间接越夏作用。当田间病残体上闭囊壳量大 ,影响自生麦苗发病的先决条件主要是阴湿环境。夏季持续干旱 ,田间病残体上的闭囊壳可存活到 9月下旬 ,有向秋苗提供菌源的机会 ,但作用不大 The results showed that the sexual period of wheat powdery mildew began to emerge at the booting stage of wheat and appeared on different susceptible cultivars through the observation on the formation and developmental stages of wheat powdery mildew during the sexual period and the infection of the autogenous germs under different conditions. Sooner or later, the amount of formation and how much there is a big difference. Closure shell in normal years can not be formed with the fall seedlings source convergence, only infected with wheat germ, in the entire cycle of infection play an indirect summer effect. When the amount of disease in the field of residual capsule shell, the main prerequisite for the impact of the incidence of spontaneous barley is the damp environment. Continued drought in summer, the field of residual disease on the capsule shell survived to the end of September, there are opportunities to provide source of bacteria to autumn seedlings, but not much