杨树白粉病病原菌的鉴定及其越冬力测定

以沈阳地区杨树白粉病为对象，观察记录病害发生的时间及症状，对病原菌进行鉴定，并对林下地表越冬的闭囊壳进行越冬力测定。结果表明，2018年该地区杨树白粉病于8月中旬至9月中旬发病，且同一派系内不同品种的发病时间存在差异；病原菌的有性型为杨球针壳，无性型为拟小卵孢属（Ovulariopsis sp.）；自然条件下闭囊壳越冬成活率达30.77%，首次得出闭囊壳的越冬力与其含子囊孢子的数目呈显著正相关关系（P<0.05），此外，在室内-40℃下处理7 d，闭囊壳的成活率为1.55%，-30℃和-35℃下处理15 d，闭囊壳的成活率分别为33.29%和31.83%。综上所述，杨球针壳具有较强的抗低温能力，可保证越冬后存活大量菌源，为侵染提供条件。

Identification of the Pathogen of Poplar Powdery Mildew and Its Overwintering Ability

Poplar powdery mildew occurring in Shenyang area was used as the research object,the time and symptoms of the disease were observed and recorded,the pathogen was identified,and the overwintering ability of cleistothecia was determined.The test revealed that the onset time of poplar powdery mildew in the region was from mid-August to mid-September in 2018,and there were differences in the onset time among different varieties.The sexual type of the pathogen was Phyllactinia populi,belonging to Ovulariopsis.The survival rate of the cleistothecia in natural conditions was 30.77%,and there was a significant positive correlation between the overwintering ability of the cleistothecia and the number of ascospores (P<0.05).In addition,the survival rate of cleistothecia was 1.55% after 7-day treatment at -40℃,and after 15-day-treatment at -30℃ and -35℃,the survival rates were 33.29% and 31.83%,respectively.To sum up,P.populi has a strong resistance to low temperature,which can ensure the survival of a large number of bacterial sources after overwintering and provide conditions for disease infection.