造成鳳梨釋迦果腐病之Diaporthe spp. 多樣性調查及防治研究

鳳梨釋迦為臺灣生產極具國際競爭力之水果，目前外銷市場集中於東亞地區，須開發新的遠距外銷市場。鳳梨釋迦之採後處理可藉由氣調低溫貯藏延長保鮮期達四週以上，但貯藏至後熟期間常發生嚴重蒂腐問題。本研究於2018和2019年對臺東五個主要產區：卑南鄉、鹿野鄉、東河鄉、臺東市和太麻里鄉進行田間菌相調查，Diaporthe spp. 於2018年及2019年分離率各佔47.6% 和 36.2%，普遍存在於鳳梨釋迦枝條、葉、花和幼果等組織，採後罹病果分離率佔 40%。挑選來自各產區和罹病果的60株Diaporthe spp. 作為代表性菌株，以ribosomal internal transcribed spacer (ITS)、β-tubulin (TUB)、translation elongation factor 1 alpha (EF1-α)、calmodulin (CAL) 和histone 3 (HIS3) 序列進行多基因親緣分析，確認D. biconispora (佔41.7%) 為鳳梨釋迦採後果腐病的主要病原菌。病原性測試以針刺製造傷口將菌絲塊接種於鳳梨釋迦果實，49株Diaporthe spp.菌株中有48株可產生病斑；無傷口接種測試12株Diaporthe spp.菌株，其中11株可產生病斑，但發病率低且病斑小。於含藥培養基上測試13種殺菌劑對11株具病原性Diaporthe spp.菌株之生長抑制效果，發現百克敏、撲克拉錳、賽普護汰寧和待克利之藥效最佳，而D. biconispora對甲基多保淨和腐絕呈現抗藥性。採後防治處理以果梗塗抹方式施用腐絕或克熱淨 (烷苯磺酸鹽) 之防治效果最佳，但貯藏三週後仍有高罹病率及罹病度。田間試驗於2018年選擇亞托待克利、賽普護汰寧和鋅錳乃浦等藥劑輪用，2019年測試百克敏和得克利同時施用、提早套袋、特殊套袋等方式，2018年及2019年各僅於一處園區呈現比慣行農法較佳之防治成效，但皆無法顯著有效抑制採後病害。透過調查果梗及果肩上病原菌潛伏感染情形，結合田間試驗之觀察結果，推測田間防治時機須再提前至花期，並加強田間衛生管理，才可能成功防治鳳梨釋迦採後病害。

關鍵字

番荔枝；鳳梨釋迦；採收後病害；果腐病； Diaporthe spp. ；潛伏感染；殺菌劑；套袋

並列摘要

Atemoya fruits produced in Taiwan have high international competitiveness, however a high percentage of Taiwanese atemoya is exported to East Asia. It is necessary to explore long-distance overseas markets. Although atemoya fruits can retain the freshness for more than four weeks in a controlled-atmosphere and low-temperature condition, severe stem-end rot can occur during the ripening stage. In this study, field surveys for fungal pathogens were conducted in 2018 and 2019 in five main production areas in Taitung: Beinan Township, Luye Township, Donghe Township, Taitung City and Taimali Township. Thepercentage of isolated Diaporthe spp. were 47.6% (2018) and 36.2% (2019) from the field, and 40% from diseased postharvest fruits. This indicates that Diaporthe spp. were widely present in the twigs, leaves, flowers, and young fruits of atemoya. Sixty Diaporthe spp. were selected as representatives for multi-gene phylogenetic analysis with ribosomal internal transcribed spacer (ITS), β-tubulin (TUB), translation elongation factor 1 alpha (EF1-α), calmodulin (CAL) and histone 3 (HIS3). D. biconispora (41.7% of all isolates) was identified as the major pathogen causing postharvest fruit rot disease in atemoya fruits. By inoculating mycelial plugs on wounded atemoya fruits, 48 out of 49 Diaporthe spp. isolates caused lesions; when inoculating on non-wounded fruits, 11 out of 12 Diaporthe spp. isolates caused lesions, with relatively lower incidence and smaller size. The sensitivity of 11 pathogenic Diaporthe spp. isolates to 13 fungicides were tested by evaluating the inhibition of mycelial growth on the medium containing fungicides. Pyraclostrobin, prochloraz-manganese, cyprodinil + fludioxonil, and difenoconazole showed the highest inhibitory effect, and D. biconispora showed resistance to thiophanate-methyl and thiabendazole. The most effective postharvest treatment tested was application of thiabendazole or iminoctadine tris (albesilate) by brushing on the fruit pedicel. However high disease severity and incidence was observed after a three-week storage period. Field trials were also conducted to investigate the control effects of rotating azoxystrobin + difenoconazole, cyprodinil + fludioxonil, and mancozeb in 2018, and the integrated application of both pyraclostrobin and tebuconazole, early bagging, and special bagging in 2019. In both 2018 and 2019, we only observed better results from the experimental treatments than conventional practices in one experimental orchard, but the occurrence of postharvest diseases was not significantly suppressed. Based on the observations from the field trials, as well as the survey of latent pathogens on the fruit pedicel and shoulder, it is speculated that management of postharvest atemoya diseases will require the application of control measures as early as at the flowering stage and good field sanitation practices.