梨黑星病是危害梨树的头号病害,在我国梨产区普遍发生,北京市、河北、河南、山东、陕西、山西和辽宁省较为严重。北京市门头沟区京白梨曾连续多年果实受害严重,河北鸭梨产区20世纪七八十年代病果率多在60%以上;近年红肖梨黑星病发生也呈上升趋势。在北京地区,一般年份5月10-15日被害芽长出的新梢或花序初见“乌码子”;在5月底“乌码子”数量增多,并见病叶,挑取“乌码子”部位霉层,显微镜下见大量分生孢子及分生孢子梗;6月份见“乌码子”下部及周围病叶数量缓慢增多;进入雨季后,病叶、病果数量急剧增多。病情严重树在8月中下旬病叶、病果满树可见。1危害症状幼果及生长中期果实被害,先出现淡黄色病斑,病斑扩大后长出黑色霉层,有的不长霉层,变为黑绿色斑。病斑处果肉变硬、停止生长,随着果实增大,病斑处凹陷、裂口。病斑长黑色霉层的病果,后期可被粉红聚 Pear scab is the number one disease endangering the pear tree, which is common in the pear-producing areas of our country, while Beijing, Hebei, Henan, Shandong, Shaanxi, Shanxi and Liaoning provinces are more serious. Jingbai Pear in Mentougou District, Beijing, suffered severe damage to fruit for many years in succession. The incidence rate of disease in Hebei Yali Pear Area in the seventies and eighties of the 20th century was more than 60%. In recent years, the incidence of scab was also on the rise. In Beijing area, the new shoots or inflorescences of the victim buds usually appear on the May 10-15 May of the year, and the number of “Umbilicus” increased at the end of May, A large number of conidia and conidiophores were seen under the microscope. The number of diseased leaves in the lower part and around the “Wumazi” increased slowly in June. After entering the rainy season, the number of diseased leaves and diseased fruits A sharp increase. Severe illness in late August disease leaves, disease fruit trees can be seen. 1 Harmful symptoms of fruit and mid-growth of the fruit were killed, the first yellowish spot, the lesion expanded to grow black mildew layer, some non-mildew layer, into dark green spots. Lesions at the flesh harden, stop growing, with the fruit increases, lesion at the depression, rips. Black moldy lesions of the disease, the late pink can be poly