First Report of a Leaf Spot and Stem Canker Caused by Myrothecium roridum on Watermelon in the United States
Autor: | Kenneth W. Seebold, J. E. Hudgins, Robert C. Kemerait, David B. Langston |
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Rok vydání: | 2019 |
Předmět: | |
Zdroj: | Plant disease. 89(3) |
ISSN: | 0191-2917 |
Popis: | Myrothecium roridum Tode:Fr, pathogenic to a number of cucurbit species, causes fruit rots, cankers on crowns and stems, and leaf spots. Hosts include cantaloupe and honeydew (Cucurbita melo) and cucumber (Cucumis sativus) (1,3). In June 2004, following a period of heavy rainfall, numerous round-to-oblong, brown lesions with concentric rings were observed on leaves of watermelon (Citrullus lanatus) cv. Desert King at the Blackshank Farm in Tifton, GA. Disease was localized in the field and severity was low (5 conidia per ml) plus 0.1% vol/vol Tween 20. Inoculum was applied on leaves and stems until runoff with a hand-held mister, and plants were placed in a dew chamber for 72 h. Ten plants were sprayed with sterile, distilled water to serve as controls. Inoculated and noninoculated control plants were removed from the dew chamber and maintained at 25 to 28°C. Symptoms appeared 8 days after inoculation and were characterized by round, dark lesions with concentric rings; noninoculated plants were symptomless. Sections of symptomatic tissue were plated, and M. roridum was reisolated. Although M. roridum is a common pathogen of melons and cucumber, to our knowledge, this is the first field report of a leaf spot caused by M. roridum on watermelon in the United States. No further occurrences of the disease on watermelon have been observed in Georgia since the initial discovery of M. roridum in 2004; however, losses could be potentially severe if widespread infection of fruit were to occur. References: (1) B. D. Bruton. Crater Rot. Pages 49–50 in: Compendium of Cucurbit Diseases. T. A. Zitter et al., eds. The American Phytopathological Society, St. Paul, MN, 1996. (2) M. B. Ellis. Page 552 in: Dematiaceous Hyphomycetes. CAB International, Wallingford, UK, 1971. (3) D. F. Farr et al. Page 809 in: Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. |
Databáze: | OpenAIRE |
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