疫病菌引起之馬拉巴栗苗木腐敗

陳麗鈴(L. L. Chern) ； 安寶貞(P. J. Ann) ； 蘇俊峯(J. F. Su) ； 王姻婷(I. T. Wang) ； 楊正偉(C. W. Yang) ； 蔡幸君(H. C. Tsay) ； 蔡志濃(J. N. Tsai) ； 林筑蘋(J. P. Lin) ； 謝廷芳(T. F. Hsieh)

《植物病理學會刊》 23卷3&4期 (2014/09) Pp. 237-245

https://doi.org/10.6649/PPB.201409_23(3_4).0001

摘要

馬拉巴栗苗木是我國重要之外銷觀葉植物，主產區在彰化溪洲一帶。近年來，田間栽培的馬拉巴栗苗木經常發生腐敗情形，造成苗木死亡、失編及出口貨品腐敗。本試驗發現疫病菌為引起馬拉巴栗苗木腐敗的重要病原菌之一，它可以感染馬拉巴栗全株，無論在苗期、編苗時期或本田期均可發生，愈年幼的苗木發病愈嚴重。幼苗染病時，葉片、新梢及莖部會出現水浸狀不規則淡褐色病斑，繼之病斑擴展，導致葉片褐化與落葉、新梢與莖部枯萎，甚至造成植株死亡。本田期的病徵主要出現在葉片與根系，造成葉片褐斑與細根腐敗。疫病在苗編時期亦會發生，主要造成根部水浸狀腐敗，苗木失編。田間調查結果顯示約有30%以上的苗圃罹患疫病，本試驗自47處田區、編苗場及集貨場分離得疫病菌。分離得到的疫病菌主要有兩種，包括Phytophthora palmivora與Phytophthora nicotianae（=P. parasitica），大部分為A^1配對型，極少部分為A^2配對型。兩種疫病菌在12-34℃均可生長。此外，接種試驗結果顯示，P. palmivora引起的疫病在16-32℃均會發病，最適合發病的溫度為28℃。疫病在多雨期發病嚴重，春天播種的苗木在梅雨季節與夏秋季播種的苗木於颱風季節均容易得病。病害的初次感染源可來自連作田受污染的土壤或鄰近的馬拉巴栗田區，環境合適時，病害一發不可收拾，嚴重時，田間發病率可高達50-75%以上。P. palmivora與P. nicotianae引起的馬拉巴栗疫病為國內首度正式報導。

關鍵字

馬拉巴栗 ； 疫病

並列摘要

Malabar chestnut (Pachira macrocarpa Schl. et L. H. Bailey) seedlings are important potted ornamental plants for export from Taiwan. The seedlings can be potted alone or braided in groups of three or five. The main production area of Malabar chestnut in Taiwan is Sijhou in Changhua County. In recent year, the production of Malabar chestnut has been impacted with diseases that cause root and basal rots of seedlings, leading to the death of seedlings in the field, loss of braids, and rots of plants in storage container during shipping. Our previous studies indicate that Phytophthora spp. are the major microorganisms that cause the disease. Results of this study showed that Phytophthora spp. were able to infect entire Malabar chestnut plant at any production stages, including seedling, braiding, and growth in the field. The plants were most susceptible at the seedling stage. Symptoms of infected seedlings included water-soaking, irregular-shaped brown lesions on leaves, shoots, and stems. In the field, the disease mainly affected leaves and roots, causing brown foliar lesions and root rot. At the seedling braiding stage, Phytophthora infection caused water-soaking lesions of roots and loss of braids. Our survey showed that more than 30% of the Malabar chestnut nurseries were affected by diseases caused by Phytophthora spp. Isolates of Phytophthora were obtained from 47 locations, including nurseries, cultivation fields, braiding houses, and packaging houses, and identified as Phytophthora palmivora and Phytophthora nicotianae (=P. parasitica). Most of the isolates were A^1 mating type, and only a few were A^2. Both species could grow at temperature ranging from 12 to 34℃ with an optimum growth at 28℃. Inoculation study showed that P. palmivora could cause disease at 16℃ to 32℃ with the optimum temperature at 28℃. Phytophthora diseases were more serious in wet seasons. Seedlings planted in spring and summer/autumn were most vulnerable due to rainy weather and typhoons. The primary inoculum could come from the infested soils of Malabar chestnut monocropping field and nearby cultivation fields. The Phytophthora diseases of Malabar chestnut were devastating when the environmental conditions were suitable for disease development, reaching infection rates of 50-70%. This is the first official record of Phytophthora diseases of Malabar chestnut caused by P. palmivora and P. nicotianae in Taiwan.

並列關鍵字

Phytophthora disease ； Malabar chestnut ； Phytophthora palmivora ； Phytophthora nicotianae