|Keywords:||甘藷;系統性病害;粉蝨;sweet potato;systemic disease;whitefly||Issue Date:||Jun-1985||Publisher:||台灣：植病保護學會||Start page/Pages:||333-341||Source:||植物保護學會會刊,27(4):||Abstract:||
經菸草粉蝨(Beinisia tabaci Genn.)之媒介，從病毒複合感染之甘藷葉片中，分離出甘藷捲葉病病原。罹病甘藷沿葉緣或葉尖向上捲曲，下表面葉脈有輕微突起現象。此病徵在甘藷生育初期及高溫季節較明顯，低溫或生育中、後期則有病徵消失現象。菸草粉蝨獲毒吸食一天即可傳指本病。蟲體吸食一天後，持續至第六天仍能傳播本病。每株接種蟲數達20隻以上時，其發病率連75-100％。本病不經蚜蟲和機械接種方式傳播，亦不經種子傳播。寄主範圍限於旋花科植物，能感染Ipomoea nil, I. setosa及I. quamoclit等造成嚴重的捲葉，縮葉及矮化病徵。罹病的甘藷葉片以超薄切片法行電子顯微鏡檢查結果，在靭皮細胞之細胞質中觀察到寬約18nm，桿狀之顆粒集團，顆粒之斷面具中心孔，可能為本病原之病毒顆粒。
A leaf curl disease of sweet potato (Ipomoea batatas (L) Lam.) was found in Taiwan. During the hot season (from May to September), the disease symptoms of upward leaf curling and vein, swelling occur mainly on young plants which were infected and remained almost symptomless in the other seasons. Similar symptoms appeared to be more severe than on sweet potato were also observed on Ipomoea nil, I. quamoclit and I. selosa.
The leaf curl symptoms were reproduced on healthy sweet potato seedlings by grafting or whitefly (Beinisia tabaci Genn.) transmission, while not by aphid, mechanical or seed transmission. In case mechanical inoculation to I. nil, sweet potato virus A (SPV-A) and/or sweet potato virus N (SPV-N) symptoms rather than leaf curl symptoms usually developed on the inoculated plants. This suggests that the leaf curl disease of sweet potato found in field is complexed by some other viral infection, and that whitefly transmits only the sweet potato leaf curl disease agent.
Further study indicated that whitefly acquires the disease agent, by feeding on disease plant for more than. 24 hours and infectivity persists throughout the life span, about 5 to 6 days. The disease can be transmitted by just two but not by only one whitefly. Effective transmission was obtained when 20-100 insects per plant were used.
Host range of the whitefly-transmitted disease agent appeared to be limited in Convolvulaceae. Electron microscopy of ultrathin sections from sweet potato plants which were affected by the leaf curl disease agent, revealed that virus-like, rod-shaped particles, approximately 18 nm in width, were present in the cytoplasm of phloem cells. The Involement of these virus-like particles in the leaf crul disease of sweet potato need to be further investigated.
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