臺灣洋菇之細菌性褐菇病

Bacterial: Blotch of the Cultivated Mushroom in Taiwan

臺灣栽培之洋菇已證實有細菌性褐菇病或褐斑病（Bacterial blotch），其病徵為菇傘表面局部變為褐色或深褐色，嚴重時擴展至整個表面而成褐菇，被害部常出現裂紋，菇柄亦可被害。由病菇分離之細菌，經測定其培養性質，生理性質及病原性顯示與Pseudomonas tolaasi極為相似。由室內之接種試驗得知剛出土之幼小菇體病徵不易顯現，其餘各種大小菇體均能被為害。在濕度高，尤其是菇傘表面潮濕時適宜發生本病，但相對濕度在約34%時亦能發病，因此相對濕度高並非發病之絕對條件。溫度於8〜l8°C間有利於發病，但在約5°C時亦能產生輕微之病徵。由菇舍採回之洋菇，雖外觀健全，但也有附著病菌之可能，若將該等洋菇置於多濕低溫處，病徵即能顯現。

Bacterial blotch of the mushroom was shown to occur in Taiwan, and has became prevalent in certain mushroom growing areas. The causal organism was confirmed as Pseudomonas tolaasi based on its morphological, cultural and physiological characteristics, and pathogenicity to the mushroom. Laboratory inoculation tests showed that sporophores at all stages of development except for very young stages were susceptible to the disease. High relative humidity was favorable for the disease development, but the symptoms were also observed when relative humidity was at about 34%. Temperatures between 8 and 18°C were suitable for infection, however, mild symptoms were also induced at temperature around 5°C. Some of the apparently healthy mushrooms collected from beds developed the symptoms at 3 days after being placed in a environment where relative humidity was high and temperature was relatively low. This indicates that although the mushrooms are symptomless at the time of picking, but may have carried the pathogen, and can still be infected during storage or transport.