由Exserohilum rostratum引起之蝴蝶蘭花瓣斑點病

Petal Spot of Phalaenopsis Caused by Exserohilum rostratum

黃巧雯(Chiao-Wen Huang) ； 黃晉興(Jin-Hsing Huang) ； 蔡志濃(Jhih-Nung Tsai) ； 張立詳(Li-Hsiang Chung) ； 謝廷芳(Ting-Fang Hsieh)

《台灣農業研究》 68卷1期 (2019/03) Pp. 47-58

https://doi.org/10.6156/JTAR.201903_68(1).0005

摘要

2017年4月於台南地區一處蘭園發現蝴蝶蘭花瓣上產生褐色圓形凹陷病斑，大多數病斑產生後不會繼續擴大，但嚴重影響花卉觀賞品質，依病徵形態將本病稱為蝴蝶蘭花瓣斑點病（petal spot）。由罹病組織所分離之可疑病原菌，於Potato dextrose agar（PDA）平板培養時產生黑灰色茂密菌絲，其分生孢子（conidia）為褐色至深褐色長橢圓形，於分生孢子末端突出黑褐色之臍（hilum）。依據科霍氏法則（Koch's postulates）完成病原性測定，並由本病害之病徵表現、病原菌形態特徵及分子鑑定結果等將病原菌鑑定為Exserohilum rostratum（Drechsler）Leonard & Suggs。本菌最適菌絲生長溫度為28℃，而最適孢子發芽溫度為24－36℃。病原菌不僅危害白花蝴蝶蘭（Phalaenopsis Sogo Yukidian 'V3'）外，亦可在粉黃花（Phalaenopsis Green Pixie 'Ever Green'）及桃紅（Phalaenopsis Queen Beer 'Mantefon'）蝴蝶蘭、黃花文心蘭（Oncidesa Gower Ramsey 'Honey Angel'）、嘉德麗雅蘭（Cattleya Chien Ya 'Ocean'）及白花萬代蘭（Vanda Princess 'Mikasa White'）花瓣上造成類似病徵。測試殺菌劑對本菌之菌絲生長及孢子發芽之影響，結果顯示快得寧、撲滅寧、待克利及依普同在10 mg a.i. L^(-1)有效濃度下對菌絲生長抑制率均可達90%以上，而快得寧、鋅錳乃浦、四氯異苯腈及氫氧化銅在10 mg a.i. L^(-1)有效濃度下則可顯著降低病原菌之孢子發芽率。本文為國內第一篇闡明由E. rostratum引起蝴蝶蘭花瓣斑點病之報告，並初步篩選防治藥劑供栽培業者參考使用。

關鍵字

蝴蝶蘭 ； 花瓣斑點病 ； 藥劑篩選

並列摘要

In April 2017, flower diseases of Phalaenopsis (Sogo Yukidian 'V3') occurred in Tainan area with the symptoms showed brown small spots on petal, sometimes sunken, and about 1 mm or less in diameter without expanding. It seriously affected quality of ornamental flowers and cut flowers. The pathogen isolated from the diseased tissue produced dark grey mycelium on potato dextrose agar (PDA). Conidium is ellipsoidal to fusiform, dark brown, and with hilum. The causative fungus was identified as Exserohilum rostratum (Drechsler) Leonard & Suggs based on symptoms, morphological characteristics and ITS rDNA sequence. The pathogen not only harmed the white flowers of Phalaenopsis Sogo Yukidian 'V3', but also caused symptoms on the petals of Phalaenopsis Queen Beer 'Mantefon', Phalaenopsis Green Pixie 'Ever Green', Oncidesa Gower Ramsey 'Honey Angel', Cattleya Chien Ya 'Ocean' and Vanda Princess 'Mikasa White'. The optimal temperature was 28℃ for mycelial growth of Exserohilum rostratum and 24-36℃ for spore germination. Mycelial growth of the pathogen was effectively inhibited more than 90% by oxine-copper, procymidone, difenoconazole and Iprodione with the concentration at 10 mg a.i. L^(-1). Spore germination of pathogen was inhibited by oxine-copper, copper (II) hydroxide, mancozeb and chlorothalonil with the concentration at 10 mg a.i. L^(-1). This is the first report of Phalaenopsis petal spot disease caused by E. rostratum in Taiwan.

並列關鍵字

Phalaenopsis ； Petal spot ； Fungicide screening