Abstract The presence of well-defined and depressed circular leaf spots, dark in their core and surrounded by a light brown dim halo, was observed on Dendrobium nobile plants in the municipality of Ixtaczoquitlán, state of Veracruz, Mexico, in 2019. Colletotrichum isolates were consistently obtained from symptomatic plants of D. nobile. The morphological characteristics of these isolates resembled each other, and their pathogenicity could be confirmed based on the necrotic lesions caused by three of these isolates on D. nobile plants 10 days after inoculation. The causal agent of this disease was identified as Colletotrichum karstii, based on morphological characteristics and the partial sequences of the ITS1-5.8S-ITS2, calmodulin and β-tubulin genes of the DNA of three representative isolates(CKFG004, CKFG005 and CKFG006). To our knowledge, this is the first report which identifies C. karstii as the causal agent of anthracnose of D. nobile leaves in Mexico.

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卡尔斯提炭疽菌：墨西哥金钗石斛炭疽病的病原体

摘要 2019 年，在墨西哥韦拉克鲁斯州 Ixtaczoquitlán 市的 Dendrobium nobile 植物上观察到界限分明且凹陷的圆形叶斑，其核心为黑色，周围环绕着浅棕色昏暗的光晕。Colletotrichum 分离株是始终从 D. nobile 的有症状植物中获得。这些分离株的形态特征彼此相似，根据其中3株分离株在接种后10天对金钗植株造成的坏死病灶可以证实它们的致病性。根据形态学特征和三个代表性分离株（CKFG004、CKFG005和CKFG006）的DNA的ITS1-5.8S-ITS2、钙调蛋白和β-微管蛋白基因的部分序列，确定该病的病原体为喀斯特炭疽菌。据我们所知，