Cucumber (Cucumis sativus L.) is a nutritious domesticated vegetable which belongs to Cucurbitaceae family. India ranks 30th in global cucumber production and its total output is 1,61,000 metric tons annually. In the investigation a different kind of leaf spot disease was observed on 2 months old cucumber leaves samples from cucumber fields in Baruipur, West Bengal, India (Latitude: N 22° 22.262′, Longitude: E 88° 24.5086′). The spots appeared were large, greyish brown in colour surrounded by a yellow to brownish halo, measuring 2 × 1 cm in average. These lesions expanded gradually from circular to angular spots ultimately resulting in necrosis and defoliation. The isolated fungus showed greyish black to dark olive mycelial growth. Microscopic characterization revealed straight to slightly curved conidia and distoseptate with a distinctly protruding basal hilum. Through microscopic observation and ITS sequencing the organism was identified to be Exserohilum rostratum. E. rostratum was previously known for causing blight disease in maize as well as human immune system diseases. E. rostratum, E. longirostratum and E. mcginnisii are identified as human pathogens. Koch’s postulates were carried out and distinct symptoms were observed in cucumber. As because there is no such record, this is the first time the host pathogen combination is separated in India.

中文翻译：

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Exserohilum 叶斑病的首次报告：印度南孟加拉地区黄瓜中独特的嗜盐病原体

黄瓜（Cucumis sativus L.）是葫芦科植物营养丰富的驯化蔬菜。印度在全球黄瓜产量中排名第 30 位，其年总产量为 161,000 公吨。在调查中，在印度西孟加拉邦巴鲁伊普尔的黄瓜田（纬度：北纬 22° 22.262'，经度：东经 88° 24.5086'）的 2 个月大黄瓜叶片样本上观察到了不同种类的叶斑病。出现的斑点较大，呈灰褐色，周围有黄色至褐色的光晕，平均大小为 2 × 1 cm。这些病斑从圆形逐渐扩大到角状斑点，最终导致坏死和落叶。分离出的真菌呈灰黑色至深橄榄色菌丝生长。显微表征显示分生孢子笔直至略微弯曲，并带有明显突出的基门。通过显微镜观察和 ITS 测序，该生物被确定为 Exserohilum rostratum。E. rostratum 以前因在玉米中引起枯萎病以及人类免疫系统疾病而闻名。E. rostratum、E. longirostratum 和 E. mcginnisii 被确定为人类病原体。执行科赫假设并在黄瓜中观察到明显的症状。由于没有这样的记录，这是印度第一次分离宿主病原体组合。rostratum 以前因在玉米中引起枯萎病以及人类免疫系统疾病而闻名。E. rostratum、E. longirostratum 和 E. mcginnisii 被确定为人类病原体。执行科赫假设并在黄瓜中观察到明显的症状。由于没有这样的记录，这是印度第一次分离宿主病原体组合。rostratum 以前因在玉米中引起枯萎病以及人类免疫系统疾病而闻名。E. rostratum、E. longirostratum 和 E. mcginnisii 被确定为人类病原体。执行科赫假设并在黄瓜中观察到明显的症状。由于没有这样的记录，这是印度第一次分离宿主病原体组合。