板栗叶焦枯病相关病菌分离及病因初探

目的 近年河北板栗主产区大面积严重发生板栗叶焦枯病，造成板栗减产和栗农经济损失，该病害发病原因亟待明确，尽早进行有效的防控。 方法 通过林间症状调查和病叶组织样本微生物分离、离体叶片及盆栽苗接种致病柯赫法则验证，结合果园管理措施和环境因素分析，对病因进行了探讨。 结果 该病栗园病树率可达10%~50%，单株树病叶率可至90%以上，病叶主要症状为叶缘及叶脉间组织干枯。林间、室内湿培及显微镜切片均未发现病组织存在病症或病原菌组织。组织分离纯化获得相关微生物菌株102株，均为真菌，归属10科12属15种，丰度最高为Alternaria alternata。致病性接种试验表明，其中的Ophiognomonia setacea和Coniothyrium pyrinum能引起接种组织局部褐变发病，但症状表现与林间叶焦枯病有差异。 结论 研究发现Ophiognomonia setacea和Coniothyrium pyrinum两种真菌具有致病性，可在中国板栗引发叶斑病，但症状不同于发生于栗园的板栗叶焦枯病。当前频发性树叶焦枯病类病害常见诱发因素，多与气候变暖、异常天气、环境污染以及生产和病虫害管理措施不当引起的品种生长不适应密切关联。河北大面积发生的板栗叶焦枯病病因有待综合非侵染因子进行深入研究和探明，以期为尽快采取有效防控措施奠定基础。

Primary Study on Causes and Associated Pathogens for Chestnut Leaf Scorch

Objective To investigate and analyze leaf scorch of Castanea mollissima occurred in the main chestnut producing areas in Hebei Province. Method Combined the investigation of the symptoms in the forest, the isolation of microbes from the symptomatic leaf tissue, the confirmation of Koch's law in vitro leaves and potted seedlings, with the management measures of orchard and the environmental factors, the causes of disease were analyzed and discussed. Result The disease rate of orchard trees was 20%–50%, the disease rate of individual tree leaves can be up to 100%, the main symptom of individual leaf was dry leaf margin and interveinal tissue. No pathogen was found in the forest symptomatic tissues and microscopic examination. A total of 102 strains were isolated and purified from symptomatic tissues, all of which were fungi, belonging to 10 families, 12 genera and 15 species with Alternaria alternata as the most abundant. The inoculation test showed that Ophiognomonia setacea and Coniothyrium pyrinum could induce the browning of leaf tissue of Chinese chestnut. However, the symptom was significantly different from that of chestnut forest leaf scorch. Conclusion Two pathogens, O. setacea and Coniothyrium Pyrinum, were newly found and verified to be pathogenic to Chinese chestnut leaves, causing chestnut tree leaf spots, which were different with the leaf scorch symptoms in chestnut observed. Currently, leaf scorches in trees are ordinarily connected with environmental and physical factors which influenced tree growth with global warming, extreme weather, pollution, inadequate silviculture and control pests/diseases managements. Therefore, integrating non-infection to investigate causes of the leaf scorch of Castanea mollissima occurred in Hebei Province is strongly proposed in order to effectively prevent and control the disease as soon as possible.