由Colletotrichum orchidophilum引起的蛾形文心蘭炭疽病

南投縣埔里鎮的盆栽蛾形文心蘭Alba品種（Psychopsis kalihii, 'Green Valley'）與'Mountain'品種（Psych. mariposa）於2012年2月與7月發生一種新病害，罹病株葉片與葉鞘出現圓形到不規則形的黑色病斑，發病率介於42-63%之間。病原菌分離株在減糖1/2的馬鈴薯葡萄糖瓊脂平板培養基上，菌落呈灰色至黑色，並有橙色孢子堆產生。分生孢子呈圓柱形，大小介於2-2.5 µm × 9.9-22.3 µm。依科霍氏法則（Koch's postulates）完成病原性測定後，挑選供試菌株TJP-1537-2與TJP-1537-4，輔以internally transcribed spacer（ITS）序列比對，鑑定引起蛾形文心蘭炭疽病的病原真菌為Colletotrichum orchidophilum Damm, Cannon & Crous。本病原菌菌絲最適生長溫度為20-24℃，生長速度介於5.1-5.6 mm day^(-1)，最適發病溫度介於16-28℃之間。

關鍵字

蛾形文心蘭； Colletotrichum orchidophilum ；炭疽病

並列摘要

The field surveys were conducted at Puli Township, Nantou County in February and July 2012. Both of the oncidium cultivars Alba (Psychopsis kalihii, 'Green Valley') and 'Mountain' (Psych. mariposa) showed black spot with circular to irregular on leaves and sheath parts of diseased plants. The disease incidences were up to 42-63% in field surveys. The colony characteristics of fungi isolates from diseased plants showed gray to dark color with abundant pinkish conidia mass on 1/2 sucrose of potato dextrose agar. The conidia are cylindrical with the size ranges of 2-2.5 μm × 9.9-22.3 μm. After following Koch's postulates to make sure the pathogenicity, two isolates of TJP-1537-2 and TJP-1537-4 were chosen and submitted for further molecular identification by using sequence comparison of internal transcribed spacer (ITS) of ribosomal DNA. The pathogen causing the new recorded Psychopsis anthracnose was identified as Colletotrichum orchidophilum Damm, Cannon & Crous. Optimum temperatures for mycelial growth of pathogen ranged from 20 to 24℃, and the growth rates ranged from 5.1 to 5.6 mm day^(-1). Optimum temperatures for disease development ranged from 16 to 28℃.

並列關鍵字

Psychopsis ； Colletotrichum orchidophilum ； anthracnosec

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