樹木褐根病之研究

Abstract

樹木褐根病是台灣最重要的樹木病害，目前已記載危害100種的植物，而且正在蔓延擴散中，41種新寄主被發現。接種實驗顯示高接種源潛勢與傷口有利於完成柯霍氏法則。利用褐根病菌腐朽菌的特點，以插入竹筷子進行病區標定，可作為病區褐根病相對族群大小，有助於了解各種防治措施的效果。實驗顯示許多藥劑對褐根病菌有抑制或致死的效果，但藥劑必須與褐根病菌接觸才能達到效果，田間施用時大量的水有助於藥劑的擴散及接觸，來增加施用藥劑的效果。利用農用燻蒸劑-邁隆可有效率地殺死病區褐根腐病菌。嘗試以外科手術方式進行處理。切除被感染的根部組織，並且以快得寧及三得芬處理傷口，原本地上部黃化枯萎的枝幹，已長出新的枝葉並不再產生不正常落葉情形，判斷應已恢復健康。實驗室中哈氏木黴可成功感染褐根病菌，但哈氏木黴進行樹木褐根病防治，田間實際效果不彰。褐根病菌族群因哈氏木黴的施用而降低，但效果不似化學藥劑快速而明顯，施用區木黴族群病區開始急遽增加，但又逐漸下降。利用溫度生長試驗了台灣褐根病菌株有差異，進一步利用ITS 進行分析，台灣褐根病菌可分成兩個族群。褐根病菌除了是樹木重要的病原菌外，亦是重要的木材白腐朽真菌，可分解木材的纖維素和木質素，12週的接種可造成杉木及楠木2..8％及9.6％的重量損失，並且造成木材的崩解。

Tree brown root rot disease caused by Phellinus noxius (Corner) Cunningham. is the most important tree disease in Taiwan . 100 plant species had been reported to be infected by the pathogen, and the disease is expanding .more seriously. Another 41 tree specis are newly found to be infected by P. noxius. The result of experiment showed high inoculum potential and wounds would promote to finish the pathogenicity test. Making use of characteristic of wood decayed fungus , inserting chopsticks into the diseae area could applicably estimate the relative population size of the pathogen in the disease area, and the effect of control measures. Many fungicides showed the abililty of killing or inhibiting the pathogen , but the chemical had to touch the pathogen. In the field , a lot of water help the spread of chemical and increase the effectivity of fungicide. Dazomet is an agricultural fumigant, and kills the brown root rot fungus effectively in the laboratory and field test. Tree surgery treatment was applied to the preliminarily infected and still alive tea trees. The infected root tissues were excised, and treated the wound with fungicides Triadimefon（500X） and Qxine copper （500X）. Tree brown root rot disease was a fast wilted disease, and infected trees survived only for 3 months from falling leaves to death on general observation and documents. The tea trees have survived for more than 8 months after tree surgery and chemical treatment, and grown new twigs and leaves. These diseased trees were gradually restored. Optimal temperature range for mycelial growth of the 23 isolates P. noxious from Taiwan were very different. Using ITS analysis, the 19 P. noxious isolates can be divided into two groups. P. noxious is famous pathogen of trees and also important white wood-decayed fungus. It can decompose cellulose and lignin. Inoculating P. noxious on woodblocks of china fir and machilus tree, 2.8﹪and 9.6﹪ weight loss were caused respectively during 12 weeks test.