|Title:||非洲鳳仙花露菌病在台灣發生||Other Titles:||Occurrence and Control of Impatiens Downy Mildew in Taiwan||Authors:||黃晉興
|Keywords:||非洲鳳仙花;露菌病;防治;Impatiens walleriana;Plasmopara obducnes;control||Issue Date:||Sep-2015||Publisher:||農業試驗所||Start page/Pages:||61-74||Source:||農業試驗所特刊;第184號||Conference:||台灣新浮現之重要作物病害及其防治研討會專刊
Proceedings of the Symposium on Important New Emerging Crop Diseases Taiwan and Their Controls
鳳仙花 (Impatiens spp.) 在台灣是非常受歡迎的盆栽觀賞花卉，然而2013年2月在台灣彰化某苗圃的非洲鳳仙花（I. walleriana）發生了一種新的病害，爾後陸續在其他花圃、校園以及住家庭園皆發現此病害。罹病葉片呈現褪綠轉黃，葉背有白色黴狀物，生長勢弱且開花數減少，但無明顯壞疽病斑，罹病葉片於病害後期褐化脫落，而幼苗受感染則生長不良且亦死亡。在顯微鏡下觀查葉背的黴狀物，發現該些微生物有透明像樹枝狀的孢囊柄，孢囊柄未端有三個小枝，小枝長出透明橢圓形的孢囊，每個孢囊於水中可釋放出數個至十餘個游走子。利用引子對NL1/NL4增幅出核醣體大次單位（large ribosomal subunit）的核酸並予以解序，其序列與GenBank網站登錄的12條鳳仙花露菌Plasmopara obducnes 的序列有99-100%的相似度。以將孢囊懸浮液接種於盆栽作物上，在20℃與密封高濕度的環境下7天後即出現與田間罹病株相同的病徵，且可再觀察得原接種的病原菌，証實其病原性。經由病原菌形態、核酸序列比對與病原性，鑑定該菌為鳳仙花露菌P. obducnes。以切離葉與盆栽接種結果顯示最適發病溫度為12-20℃。以盆栽接種結果顯示該菌僅危害非洲鳳仙花與庭園鳳仙花（I. balsamina）而不危害新幾內亞鳯仙花（I. hawkeri）與其他草花。由田間藥劑防治試驗的結果顯示，噴施鋅錳滅達樂、本達樂或亞磷酸+氫氧化鉀的溶液可有效抑制病害，但停止施藥2-3週後則再度發病。
In February 2013, a new disease of Impatiens walleriana occurred in nurseries in Changhua county, central Taiwan. The infected leaves showed pale green to yellow without distinct lesions, the dorsal surface showed white mildew, and the number of flower was obviously reduced. At the late disease stage, the leaves became brown and fell off. Plants collapsed rapidly especially at high humidity. When young plants and seedlings were infected, they generally didn’t survive. Microscopical observations of the infected leaves disclosed the hyaline, tree-like sporangiophores, with three apical branchlets. Sporangia were hyaline, oblong, and could release several to more than ten zoospores. The DNA sequences encoding to the large ribosomal subunit (LSU rDNA), being amplified using primers NL1 and NL4 and then sequenced, were identical to sequences of several Plasmopara obducnes isolates deposited in GenBank. Pathogenicity was confirmed by inoculation of detached leaves and potted plants with sporangia suspension of P. obducens, and the symptoms were similar to those in the field after 7 days inoculation at 20℃. Based on morphological, molecular and pathogenic characters, the pathogen was identified as P. obducens. The disease develop optimally at 12-20℃. The host range tests showed that the pathogen only infected certain I. walleriana and I. balsamina, but not I. hawkeri and other not impatiens potted plants. In the field tests, mancozeb+metalaxyl, benalaxyl, and phophorous acid + potassium hydroxide effectively controlled the disease after 4 times spraying at one week interval. However, the disease occurred again 2-3 weeks after stop spraying chemicals.
|Appears in Collections:||植物病理組|
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