Cymbidium black rot caused by an aberrant strain of Phytophthora multivesiculata in Taiwan

in Domestic Journal (external review journal), 國內期刊(外審期刊)
標題Cymbidium black rot caused by an aberrant strain of Phytophthora multivesiculata in Taiwan
AuthorsLih-Ling Chern, 陳麗鈴, P.. J. A., & Wang 王姵兮
出版日期2011 / 6

In 1996 and 1997, a severe outbreak of a disease on Cymbidium orchid (Cymbidium hybridium) occurred in a garden in I-Lan, Taiwan, with numerous plants showing black rot symptoms on leaves, pseudostems and roots and dying. A Phytophthora-like microorganism was constantly isolated from the diseased plants and two of the eleven isolates collected from this garden were used in this study. Inoculation tests were carried out using zoospore suspensions to fulfill Koch’s postulates. Results showed that both isolates (P96013 and P96016) were pathogenic on C. hybridium with the same black rot symptoms as those developed on the naturally infected plants. The pathogenicity of these two Phytophthora-like isolates was confirmed as the organism reisolated from the inoculated plants was morphologically identical to the culture of the original inoculum. In addition to C. hybridium, the two Phytophthora-like isolates were also pathogenic on other Asian Cymbidium species, including C. ensifolium, C. sinense and C. rubrigemmum, causing black rot symptoms and death of plants. Both Phytophthora-like isolates were similar to Phytophthora multivesiculata in most of the morphological characteristics. However, they were different from P. multivesiculata in some features such as dimensions of sporangia, oogonia and oospores as well as maximum growth temperature. The ITS sequences of these two Phytophthora-like isolates were identical to that of P. multivesiculata. Based on the morphological characteristics and the molecular data, both Phytophthora-like isolates from C. hybridium were identified as an aberrant strain of Phytophthora multivesiculata. This is the first report of the aberrant strain of Phytophthora multivesiculata in Taiwan. Diseased orchid plants in the garden of Yuan-Shan, I-Lan county, were destroyed in 1998 and this aberrant strain of P. multivesiculata was not found in the survey of 1998 and 1999 in I-Lan county or any other orchid production areas of Taiwan.

期刊名稱Plant Pathology Bulletin
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