臺灣玫瑰疫病抗病品種與防治藥劑之篩選

Screening of Disease-Resistant Rose Cultivars and Control Agents for Rose Phytophthora Blight Management in Taiwan

玫瑰疫病為近年在臺灣發生的新病害，病原菌為Phytophthora nagaii及Phytophthora bishii，感染玫瑰地下部造成根部及莖基部腐敗，嚴重時造成植株死亡。本研究目的為篩選抗病玫瑰品種與防治藥劑以供病害管理參考。玫瑰盆栽接種試驗結果顯示以‘萬年紅’、‘埔里之星’、‘翡翠白’及‘金黃艾爾斯’最為感病，而‘葡萄冰山’和‘白冰山’較為抗病。進一步在田間栽培使其自然感染的試驗中，亦以‘萬年紅’及‘埔里之星’最為感病，而‘葡萄冰山’和‘白冰山’不發病。為篩選有效防治藥劑，選取18種市售的化學藥劑，於實驗室測試各藥劑對上述2種疫病菌菌絲在培養基生長的抑制效果，結果發現其中12個藥劑效果較佳（IC50低於10 mg/L）。進一步於盆栽植株人工接種前3天與接種後4天於莖基部澆灌供試藥劑各一次，以測試這些藥劑對於盆栽植株的防治效果，結果顯示亞磷酸二氫鉀、中和化亞磷酸、氟比拔克、達滅芬與曼普胺對該2種疫病菌引起之盆栽玫瑰病害都有良好的防治效果。最後在田間防治的試驗結果顯示，中和化亞磷酸與亞磷酸二氫鉀的防治效果最佳，氟比拔克次之，其餘供試藥劑（達滅芬與曼普胺）則無顯著的防治效果。

Rose blight caused by Phytophthora nagaii and Phytophthora bishii, is an emerging disease in Taiwan. It primarily infects the underground parts of roses, leading to root and basal stem rot, and, in severe cases, plant death. This study aimed to identify disease-resistant rose cultivars and screen chemicals for effective disease management. Inoculation experiments using potted rose cultivars revealed that‘Wannianhong,’‘Puli Star,’‘Jade White,’and‘Goldelse’were highly susceptible, while‘Grape Iceberg’and‘White Iceberg’exhibited resistance. Field trials under natural infection conditions corroborated these findings, with‘Wannianhong’and‘Puli Star’high susceptibility, whereas‘Grape Iceberg’and‘White Iceberg’symptomless. To identify effective fungicides, 18 commercially available chemicals were screened for their inhibitory effects on the growth of pathogen mycelia on agar medium. Among them, 12 fungicides exhibited strong inhibitory effects (IC50 < 10 mg/L). These fungicides were further evaluated by applying twice on potted roses, once at 3 days and before the other at 4 days after artificial inoculation. The results indicated that potassium phosphite, neutralized phosphorous acid,‘fluopicolide+ propamocarb hydrochloride’, mandipropamid, and‘ametoctradin + dimethomorph’significantly suppressed disease development. Field trials demonstrated that neutralized phosphorous acid and potassium phosphite offered the highest effectiveness in disease control, followed by‘fluopicolide + propamocarb hydrochloride’, while the other tested fungicides (dimethomorph and mandipropamid) showed no significant efficacy. These findings contribute to the development of integrated disease management strategies for the control of rose blight, emphasizing on cultivar selection and effective fungicide application.