(32)Occurrence of Powdery Mildew on Teak (Tectona grandis) Caused by Erysiphe (Uncinula) tectonae in Thailand

概要

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In 2000, a powdery mildew was found on teak in Chiang Mai, northern Thailand. White superficial mycelia cover the upper leaf surfaces. Conidiophores arise from the side of hyphae to bend at the base, and produce conidia singly. Conidia are cylindric, 32-36×17-20μm, without conspicuous fibrosin bodies, and produce germ tubes with lobed appressoria (Polygoni-type). Ascomata are 120-180μm in diameter. Appendages are numerous, ca 26-63 per ascoma, straight to curved, hyaline, aseptate, apex loosely to closely uncinate-circinate. Asci are 55-73×35-53μm, 2-7 per ascoma. Ascospores are ellipsoid-ovoid, 22-28×14-17μm, 2-6 per ascus. Based on the characteristics of sexual and asexual states, the fungus was identified as Erysiphe (Uncinula) tectonae (Salmon) Braun & Takamatsu. Phylogenetic analysis based on rDNA ITS sequences revealed that E. tectonae groups with E. sengokui and E. togashiana with 96% bootstrap value, although their sequence similarities were less than 90%. Morphology of ascomata was clearly different among these three species. These results show that teak powdery mildew is unique in both morphological characteristics and ITS sequence. This is the first report of powdery mildew on teak in Thailand.
日本植物病理学会の論文
2003-02-25