Cowpea is an important pulse crop cultivated in arid and semi-arid regions of the world. During field survey, a characteristic wilt was observed in around 45 ha of cowpea fields with incidence 17 - 25%. Infection was seen in pre-flowering stage and infected plants showed quick wilt symptoms with tan lesions near the stem-soil interface. Fungal pathogens associated were isolated on PDA, which produced dark to grey olivaceous colonies in the center, and aerial mycelia were appressed with floccose and white to smoke-grey. Conidia are aseptate, initially hyaline, smooth-walled, broadly ellipsoidal with rounded ends becoming dark brown. Based on these morphological features, the fungal pathogen was identified as Aplosporella sp. The ITS-rDNA region was amplified using ITS1/ITS4 primers and sequenced. The nBLAST and phylogenetic analysis confirmed the pathogen as Aplosporella hesperidica. The Koch's postulates were performed on 45 d old cowpea plants with mycelial disc of A. hesperidica. Development of typical necrotic lesions was observed after 28 d of post-inoculation and the pathogen's identity was confirmed based on re-isolation. Efficacy of fungicides evaluated in vitro showed that the pathogen is highly sensitive to systemic fungicides rather than the contact fungicides. The cowpea production was severely affected owing to the causative agent A. hesperidica. The collar rot disease of cowpea by A. hesperidica is the first report to India.

中文翻译：

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由黄花单孢菌在印度引起的豇豆(Vigna unguiculata)一种新的衣领腐烂病

豇豆是世界干旱和半干旱地区种植的重要豆类作物。在实地调查中，在大约 45 公顷的豇豆田中观察到了一种特征性的枯萎病，发病率为 17 - 25%。侵染发生在开花前期，受侵染植株表现出快速枯萎症状，茎土界面附近有棕褐色病斑。在PDA上分离出相关的真菌病原体，其在中心产生深至灰色橄榄状菌落，气生菌丝被絮状和白色至烟灰色附着。分生孢子是无分隔的，最初是透明的，壁光滑，宽椭圆形，末端圆润，变成深棕色。基于这些形态特征，真菌病原体被鉴定为 Aplosporella sp。使用 ITS1/ITS4 引物扩增 ITS-rDNA 区域并测序。nBLAST 和系统发育分析证实病原体为 Aplosporella hesperidica。Koch 假设是在 45 天龄的豇豆植株上进行的，该植株带有 A. hesperidica 菌丝盘。接种后 28 d 后观察到典型坏死病变的发展，并根据重新隔离确认病原体的身份。体外评价杀菌剂的功效表明，病原体对内吸性杀菌剂高度敏感，而不是接触性杀菌剂。豇豆的生产受到了病原体 A. hesperidica 的严重影响。A. hesperidica 豇豆衣领腐烂病是首次向印度报告。接种后 28 d 后观察到典型坏死病变的发展，并根据重新隔离确认病原体的身份。体外评价杀菌剂的功效表明，病原体对内吸性杀菌剂高度敏感，而不是接触性杀菌剂。豇豆的生产受到了病原体 A. hesperidica 的严重影响。A. hesperidica 豇豆衣领腐烂病是首次向印度报告。接种后 28 d 后观察到典型坏死病变的发展，并根据重新隔离确认病原体的身份。体外评价杀菌剂的功效表明，病原体对内吸性杀菌剂高度敏感，而不是接触性杀菌剂。豇豆的生产受到了病原体 A. hesperidica 的严重影响。A. hesperidica 豇豆衣领腐烂病是首次向印度报告。