Koné D, Mohamed D, Soro S, Bolou Bi B A, Kouadio Y J, Ji P
University of Cocody-Abidjan, UFR Biosciences, 22 BP 461 Abidjan 22, Côte d'Ivoire.
Université de Abobo-Adamé, UFR Sciences de la Nature, 02 BP 801 Abidjan 02, Côte d'Ivoire.
Plant Dis. 2010 Nov;94(11):1379. doi: 10.1094/PDIS-06-10-0449.
Southern blight caused by Sclerotium rolfsii Sacc. was observed on okra (Abelmoschus esculentus) cv. Clemson Spineless in January 2010 during a survey of vegetable fields in Rubbino, Côte d'Ivoire, which is one of the most important areas for vegetable production. Plants exhibited symptoms of a dark brown lesion on the stems near the soil line. Upper roots became light to dark brown, the lower leaves wilted, turned yellow, and a white mat of fungal mycelium developed on the stem lesion. Numerous, white, spherical sclerotia formed on the infected stem and on soil surfaces around the infected plants. Sclerotia (0.5 to 1.2 mm in diameter) later turned tan to dark brown and the entire plant wilted. Eleven fields, with a total of approximately 26 ha surveyed, were affected and disease incidence reached approximately 15% in the fields. Sclerotia were collected and the fungus cultured on acidified potato dextrose agar (PDA) plates. The fungus grew rapidly on PDA and the hyphae at the edge of the colonies were large straight cells with one or more clamp connections at each septum. Secondary and tertiary hyphae were slender and lacked clamp connections. Whitish sclerotia were observed on the mycelial mats 5 to 7 days after incubation, which later turned tan to brown when mature. The fungus was identified as S. rolfsii based on the characteristics of mycelia and sclerotia (1). Sclerotia produced on PDA were used to inoculate okra seedlings under greenhouse conditions at rates of 10, 20, and 30 sclerotia per plant. Sclerotia were placed just under the soil surface around the root of 4-week-old seedlings of okra cv. Clemson Spineless. Symptoms identical to those on field samples developed on all inoculated plants. S. rolfsii was reisolated from diseased plants and the identity was confirmed. S. rolfsii has previously been reported as causing disease in Côte d'Ivoire (2). To our knowledge, this is the first report of southern blight caused by S. rolfsii on okra in this country. Okra is an important vegetable crop in Côte d'Ivoire and therefore the occurrence of southern blight and susceptibility of okra cultivars to this disease needs to be taken into account in okra production. References: (1) Z. K. Punja and A. Damiani. Mycologia 88:694, 1996. (2) R. Resplandy et al. Ann. Epiphyt. 1:1, 1954.
2010年1月，在科特迪瓦鲁比诺的蔬菜田调查中，在秋葵（Abelmoschus esculentus）品种Clemson Spineless上发现了由齐整小核菌（Sclerotium rolfsii Sacc.）引起的白绢病，鲁比诺是蔬菜生产的重要地区之一。植株在靠近土壤线的茎上出现深褐色病斑症状。上部根系变为浅褐色至深褐色，下部叶片枯萎、变黄，茎部病斑上形成白色真菌菌丝体垫。在受感染的茎上以及受感染植株周围的土壤表面形成大量白色球形菌核。菌核（直径0.5至1.2毫米）后来变为棕褐色至深褐色，整株植物枯萎。共调查了11块田地，总面积约26公顷，均受到影响，田间发病率约为15%。收集菌核并在酸化马铃薯葡萄糖琼脂（PDA）平板上培养该真菌。该真菌在PDA上生长迅速，菌落边缘的菌丝是大型直细胞，每个隔膜处有一个或多个夹状连接。次生和三生菌丝细长，没有夹状连接。培养5至7天后，在菌丝体垫上观察到白色菌核，成熟后变为棕褐色至褐色。根据菌丝体和菌核的特征，该真菌被鉴定为齐整小核菌（1）。在温室条件下，用PDA上产生的菌核以每株10、20和30个菌核的接种量接种秋葵幼苗。将菌核放置在4周龄秋葵品种Clemson Spineless幼苗根部周围的土壤表面下方。所有接种植株都出现了与田间样本相同的症状。从患病植株上重新分离出齐整小核菌并确认了其身份。此前已有报道齐整小核菌在科特迪瓦引起病害（2）。据我们所知，这是该国首次报道齐整小核菌引起秋葵白绢病。秋葵是科特迪瓦的一种重要蔬菜作物，因此在秋葵生产中需要考虑白绢病的发生以及秋葵品种对该病的易感性。参考文献：（1）Z. K. Punja和A. Damiani。《真菌学》88:694，1996。（2）R. Resplandy等人。《植物病理学年报》1:1，1954。
