台灣香菇段木上炭角菌之鑑定與藥劑感受性試驗

Abstract

台灣段木香菇年平均產量約為264 Mg，占香菇市場的0.6%，栽植地區主要分布於宜蘭縣、桃園市、新竹縣、苗栗縣、南投縣及屏東縣等山區原鄉社區。段木上常見之微生物多屬於木材腐朽菌，此些微生物造成段木香菇產量與品質之影響甚少研究。然而，近年來由於農業委員會林下經濟政策之推動，使段木香菇栽種面積增加，因而段木香菇栽培過程中之病蟲害問題也漸受重視。本研究自嘉義縣阿里山鄉栽植香菇之段木上，進行炭角菌之採集與分離，經田間子實體外觀比較和internal transcribed spacer (ITS) 序列分析後，初步鑑定為Xylaria 屬之真菌。以平板進行對峙培養試驗得知，炭角菌和香菇之菌絲接觸時，香菇菌絲除生長受影響外，更出現弱化之情形，再經2 wk 培養，炭角菌菌絲甚至包覆香菇菌絲繼續生長，顯現所分離之炭角菌可對香菇菌絲造成危害。進一步以60% 腐絕水懸劑進行藥劑試驗，結果顯示炭角菌於含30 ppm 腐絕之potato dextrose agar (PDA) 培養基和稀釋1,000× 腐絕 [60% suspension concentrates (SC)] 之濾紙圓片處理組中其生長皆受抑制，顯示此藥劑具有可作為防治炭角菌之化學藥劑的潛力。本研究為台灣首篇探討炭角菌影響台灣段木香菇生產之報導，未來也將持續調查國內各段木香菇產區的炭角菌發生情形，以作為擬定香菇段木上炭角菌防治策略之參考依據。 In recent years, the average production of wood log shiitake in Taiwan was 264 tons, accounting for 0.6% of the market share in shiitake. The planting areas are mainly distributed in indigenous community of Yilan, Taoyuan, Hsinchu, Miaoli, Nantou, and Pingtung. Common microorganisms occurring during wood log cultivation belong to wood-decaying fungi. In addition, there was little domestic research about the effect of wood-decaying fungi on the yield and quality of wood log shiitake. Due to the “under-forest economy” policy promoted by the Council of Agriculture, Executive Yuan, ROC, the planting area of wood log shiitake has increased yearly. The government has also paid the attention to the diseases and pests or competitors that occurred during the cultivation of wood log shiitake. In this study, a fungus was isolated from the shiitake wood log collected from Alishan, Chiayi, and evaluated in our Mushroom Research Laboratory. After comparing the appearance of the fruiting bodies in the field and analysis of its ITS sequence, the fungus was preliminarily identified as Xylaria sp. A dual culture assay showed when the mycelium of Xylaria sp. CYX-1 confronted with that of Lentinula edodes Br-1 on a potato dextrose agar (PDA) medium, the mycelial growth of the latter was significantly inhibited. After two weeks of culturing on the medium, the mycelium of Xylaria sp. could cover that of L. edodes. It showed that Xylaria sp. CYX-1 was detrimental to the mycelial growth of L. edodes Br-1 and could be the competitor of the latter. The recommended fungicide thiabendazole for application in the cultivation of shiitake was used in this study to test the fungicide sensitivity of Xylaria sp. CYX-1. The result showed that the mycelium of Xylaria sp. CYX-1 was totally inhibited on the PDA medium with 30 ppm of thiabendazole and in a filter paper-disk test with 1,000 dilution fold of thiabendazole [60% suspension concentrates (SC)]. Therefore, thiabendazole could potentially be used to control Xylaria sp. This is the first report on the possibility of Xylaria sp. as a competitor of shiitake cultivation on the wood log in Taiwan. Further surveys of the damage caused by Xylaria sp. in other planting areas of wood log shiitake will be needed. The results of the fungicide sensitivity of Xylaria sp. to thiabendazole may provide an important reference to control Xylaria sp. during shiitake wood log cultivation.