洋香瓜果腐病菌之特性與其對藥劑之感受性

自2019起，中部地區多處洋香瓜果園發現果實出現褐色水浸狀凹陷病斑，嚴重時造成裂果或果腐等情形，對農友收成產生極大損失，該病徵與2022年報導由Fusarium incanatum-equiseti species complex（FIESC）引起之洋香瓜果腐病相似。本文為釐清本病害病原與可能防治藥劑，自彰化縣（田尾與秀水）與臺中市（烏日與霧峰）分別蒐集罹病果體進行病原菌分離，並成功取得4株供試菌株（FE01-FE04）。病原性測試結果顯示，克霍式法則試驗指出供試菌株（FE01）的菌絲與孢子皆對洋香瓜果實具病原性，且所引起病徵與田間相似。供試菌株於馬鈴薯葡萄糖瓊脂（Potato Dextrose Agar, PDA）培養基上之菌落形態，出現明顯氣生菌絲，且顏色為白色、淡橘至粉紅色，有明顯黃色色素沉積。孢子形態僅觀察到鐮刀型大孢子（macroconidia）及厚膜孢子（chlamydospore），無觀察到小孢子（microconidia）生成。進一步透過利用internal transcribed spacer region（ITS）、β-tubulin2（β-tub2）及translation elongation factor 1 alpha（EF-1α）等三個基因片段進行多重序列比對，確認供試菌株可歸屬至FIESC內之F. sulawesiense（FIESC16）與F. pernambucanum（FIESC17）二個分類群，又以F. pernambucanum為此病害的優勢菌株，且已完成病原性測定。後續挑選三氟敏、四氯異苯腈、貝芬替、氟克殺及氟派瑞，共5種藥劑進行供試菌株藥劑感受性測試。結果發現田尾地區菌株在貝芬替與三氟敏有明顯抗藥性現象出現，而氟克殺與氟派瑞普遍抑制效果不佳，四氯異苯腈對F. pernambucanum抑制效果顯著，對F. sulawesiense則無抑制性。

關鍵字

洋香瓜果腐病； Fusarium incanatum-equiseti species complex ；藥劑感受性分析； Fusarium sulawesiense ； Fusarium pernambucanum

並列摘要

A newly emerging disease with brown spots and water-soaked symptoms on muskmelon has been reported in the central region of Taiwan since 2019. The fruits showed crack and rot symptoms and made severe losses to the yield. The symptoms are similar to the Fusarium incanatum-equiseti species complex (FIESC) which has been published to cause the fruit rot disease in Taiwan in 2022. To clarify the characteristics and controlling methods of this pathogen, four isolates were collected from the diseased fruit samples in Changhua County (Tianwei and Xiushui Township) and Taichung City (Wuri and Wufeng Dist.), respectively. The pathogenicity test results indicated that the FE01 isolate, using spores or mycelium as an inoculum source, could infect the muskmelon fruits without wounds and causing the same fruit rot symptoms in the field. These isolates could produce abounded aerial hyphae with white, light orange to pink color on Potato Dextrose Agar medium and accumulated yellow pigment on the back side of the medium. The macroconidia and chlamydospore were found in all tested isolates, and no microconidia were observed. The multiple sequence alignment method was used in this study with internal transcribed spacer region (ITS), β-tubulin2 (TUB2), and translation elongation factor 1 alpha (EF-1α) gene sequences. The phylogeny results indicated that the four isolates could be attributed to Fusarium sulawesiense (FIESC 16) and F. pernambucanum (FIESC 17) in Fusarium incanatum-equiseti species complex (FIESC). Moreover, the sensitivity of FIEST isolates on five fungicides (trifloxystrobin, chlorothalonil, carbendazim, fluxapyroxad and fluopyram) were evaluated with the inhibition efficacy on mycelial growth rate and spore germination rate. The results indicated that the Tianwei isolate strongly resisted trifloxystrobin and carbendazim. Furthermore, the inhibition ability of fluxapyroxad and fluopyram was not practical for the tested isolates. The chlorothalonil had a significant inhibition efficiency on F. pernambucanum, but not on F. sulawesiense.

並列關鍵字

Muskmelon fruit rot disease ； Fusarium incanatum-equiseti species complex ； fungicides sensitivity ； Fusarium sulawesiense ； Fusarium pernambucanum

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