由 Sclerotium rolfsii 引起之甘藷白絹病

甘藷白絹病為2015 年陸續在彰化、雲林及屏東甘藷栽培田出現之嚴重病害。其主要病徵為藷塊上產生黃褐色圓型病斑，大多數病斑在甘藷採收後雖不會繼續擴大，但嚴重影響品質。由病組織所分離之病原菌，培養時產生白色菌絲，具有扣子體，並會產生褐色菌核 (brown sclerotia)，依據形態及分子鑑定為Sclerotium rolfsii Sacc.。本菌於15-35℃培養時菌絲均會生長，30℃為最適生長溫度。病原菌不僅在甘藷藷塊造成病斑，亦對葉用甘藷苗具有病原性，造成幼苗莖基部褐化，植株倒伏，枯死。測試9 種殺真菌劑對本菌菌絲之生長抑制情形，結果顯示50.0% 福多寧 (flutolanil)、75.0% 滅普寧 (mepronil)、7.5% 依普座(epoxiconazole)、23.0% 菲克利 (hexaconazole) 及25.0% 賓得克利 (pencycuron + btebuconazole) 在10 mg a.i. L^(-1) 有效濃度下對其菌絲生長抑制率均可達89.2% 以上。本文為國內第一篇闡明由S. rolfsii 引起之甘藷白絹病並提供防治藥劑篩選結果之報告，可供農業研究人員參考。

關鍵字

甘藷；白絹病；藥劑篩選

並列摘要

In 2015, a severe disease outbreak on sweet potato storage root with the symptoms of circular yellowish brown to brown lesions occurred in Chunghua, Yunlin, and Pingtung areas. The pathogen isolated from the diseased tissue had white mycelium, clamp connection, and it produced brown sclerotia, which was identified as Sclerotium rolfsii Sacc. based on these morphological characters and ITS sequence. The growth temperature of pathogen isolates ranged from 15 to 35℃, and the optimum growth temperature was 30℃. The pathogen isolate, SCL-003, showed pathogenic ability on sweet potato storage roots and seedlings. Nine fungicides were selected for evaluating the inhibition effect on mycelial growth of two pathogen isolates (SCL-001 and SCL-003). The results showed that the effective fungicides with more than 89% inhibition rate were 50% flutolanil, 75.0% mepronil, 7.5% epoxiconazole, 23.0% hexaconazole, and 25.0% pencycuron + tebuconazole with 10 mg a.i. L^(-1) dilution concentration. This is the first report of circular spot disease on sweet potato caused by Sclerotium rolfsii in Taiwan.

並列關鍵字

Sweet potato (Ipomoea batatas) ； Circular spot diseases ； Fungicide screening

國際替代計量

由 Sclerotium rolfsii 引起之甘藷白絹病

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