向日葵細菌性軸腐病之特性、品種抗性及藥劑篩選

Abstract

民國91 年6 月，在苗栗縣大湖地區所種植之向日葵發生植株葉片乾枯萎凋的徵狀，但莖仍直立於田間，切開莖部，其內部已成中空且具水浸狀腐爛，若發生於植株莖苗期被害，嚴重者倒伏死亡。92 年夏天同樣情形再度發生。經柯霍氏法則確認該病原為細菌。經生理生化，Biolog 鑑定及專一性引子進行PCR 分析等測定，確認該病原菌包括Erwinia chrysanthemi (Ech) 及E. carotovora pv. carotovora (Ecc)。該病原菌主要造成向日葵植株軸心中空及腐爛，進而引起植株萎凋枯死，因此稱為向日葵細菌性軸腐病（stalk rot）。由Ecc 及Ech 引起之向日葵細菌性軸腐病為台灣向日葵首次記錄。品種抗性測定發現供試九種向日葵品種中以東北八重最為感病，月光及光輝雖感病但抗性較強。軸腐病菌對馬鈴薯塊莖、大白菜梗、胡蘿蔔塊根均具強致腐能力。測試市售11 種藥劑在一般使用濃度下以紙圓盤法測試對軸腐病菌菌株生長之抑制效果，顯示除甲基鋅乃浦對該病菌之生長無抑制作用外，其餘 10 種包括鏈黴素、四環黴素、鏈四環黴素、嘉賜黴素、多保鏈黴素、氫氧化銅、鹼性氯氧化銅、嘉賜銅、鋅錳乃浦及鋅錳滅達 樂等藥劑均能抑制其生長，且以四環黴素藥劑之效果最佳。 Severe stalk rot of sunflower was first found in Tahu, Miaoli County in 2002. The disease mainly appeared on the stem and caused water-soaked symptoms. In some severe cases, the stem pith disintegrated and showed hollow stem symptoms. The pathogens were identified as Erwinia chrysanthemum and E. carotovora subsp. carotovora based on physiological and chemical tests, Biolog identification, and PCR analysis. This is the first record of the disease occurring in Taiwan. Resistance screening indicated that “Tohokuhae” was the most sensitive cultivar and “Moon bright” and “Sunbright” showed better resistance when inoculated with Ech. Among 11 bactericides screened, tetracycline proved to be the most effective.