| Summary: | 碩士 === 國立臺灣大學 === 植物病理與微生物學研究所 === 104 === Urban trees were frequently infected by wood decay fungi and caused wood rot, wound and cracking. Thus make them easily to fall down after strong wind and threaten the public safety. This study is aimed to survey the rotten trees in northern Taiwan, collect the wood decay samples, and isolate the wood decay fungi from infected trees. A total of six of wood decay fungi were identified in this study. They are Ganoderma weberianum, Ganoderma gibbosum, Phlebiopsis ravenelii, Leiotrametes lactinea, Hydnochaete japonicaz and one uncertain isolate. They were tested for their capability for producing the decomposition enzymes for cellulose and lignin. Results showed that all six fungi can produce cellulase and laccase enzyme that belong to the lignin decomposition enzyme. Among the six fungi, DW04 (Phlebiopsis ravenelii) and OG12 (Ganoderma weberianum ) showed the highest yield of cellulose, while OG12 (Ganoderma weberianum ) and OG03 (Ganoderma gibbosum ) produce the highest level of laccase enzyme. To test the wood-decaying capability, we develop a wood disc method, using 2 size of pine wood disc. Results showed that among them the DW04 (Phlebiopsis ravenelii) showed the fastest decaying speed, while the DW06 (Hydnochaete japonicaz ) showed the least capability. The dilution plate method was used to screen 14 fungicides for their inhibiting potential against the six wood decay fungi at different concentrations on PDA. Results showed that Hexaconazole, Difenoconazole, Propiconazole and Tebuconazole have higher inhibitory effect than the others. The further test on wood discs treated with fungicide showed that Difenoconazole has better inhibiting effect on Ganoderma weberianum, while Hexaconazole has a good effect on Ganoderma gibbosum. In the test of tree wound protecting agents for trees, two species (Terminalia mantalyi and Cassia fistula)of tree with age of 3 years were selected and tested. The wound were brushed with wood decay fungi, then pasted with glue materials added with Difenoconazole + Propiconazole. The reisolation rate of wood decay fungi from inoculated wounds were higher than those pasted with the Difenoconazole + Propiconazole agent. In the Cassia fistula experiment, the Difenoconazole + Propiconazole and AB glue mixture showed the best protection result. While in the Terminalia mantalyi experiment, the Difenoconazole + Propiconazole and Cement or Vaseline mixture showed the better results.
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