櫻花及常見樹木疫病蟲害診治及風險評估之研究

櫻花屬於薔薇科(Rosaceae)李屬(Prunus)的落葉喬木，在春天大量開花時期深受各界人士的喜愛。櫻花的品種繁多，在台灣所見的外來品種幾乎都是透過嫁接來繁殖，而非播種的實生苗。台灣的原生櫻花有下列五種：山櫻花(Prunus campanulata Maxim)、阿里山櫻花(Prunus transarisanensis Hayata)、蘭嶼野櫻花(Prunus grisea Kalkman)、太平山櫻花(Prunus matuurai Sasaki)和霧社櫻花(Prunus taiwaniana Hayata)，當中以山櫻花最為常見。本研究主要有6項目的，包括：(1)調查臺灣北部及中部地區櫻花及常見樹木疫病蟲害之疫病蟲害的狀況；(2)重要疫病蟲害病菌及木材腐朽菌之分離及培養；(3)木材腐朽菌分解能力之測試；(4)電子鼻作為快速診斷的應用；(5)樹木目視健康檢查及初步之風險評估；(6)重要疫病蟲害的診治案例報告。在臺灣北部及中部地區常見樹木疫病蟲害之田間調查，主要針對行道樹、校園、公園和高速公路中櫻花及常見樹木，田間調查的結果顯示，重要之病害計有褐根病、南方靈芝根基腐、韋伯靈芝根基腐、流膠病、根腐病、榆硬孔菌根基腐、枝枯病、黑腫病、穿孔病、缺鎂症等。而重要之蟲害，則有霧社血斑天牛、白蟻、橙帶藍尺蛾等。本研究經以水瓊脂培養基、MA+4選擇性培養基、酸化PDA、麥芽抽出物培養基等分離培養共得到30支菌株，進行纖維素及木質素之分解能力測試。纖維素分解能力之測試中，經羧甲基纖維素培養基法可知共12菌株具有較高的酵素強度，共5株具有較強的體外酵素。木質素分解能力之測試中，經本實驗室新近研發之松木片YMEA培養基法可知，於5個優先選取之木材腐朽菌中有2個菌株呈現出具有漆酶分泌能力。本研究亦應用Cyranose 320電子鼻經過褐根病菌子實體之訓練後用以鑑別12種其他擔子菌子實體之氣味，結果顯示不論使用32感應器全開或關閉其中6個之方法，皆無法有效區分或鑑別，說明褐根病菌子實體之氣味與其他12種新鮮擔子菌子實體之氣味應屬雷同。本研究同時使用修正過之目視樹木評估(Visual Tree Assessment)表格對櫻花與校園、公園、行道樹、以及高速公路的常見樹木進行了約2900棵樹木的常規健檢及初步之風險評估，結果顯示導致樹木嚴重危害或衰退的害因中，以「腐朽」、「衰弱」、「樹皮受損」、「樹幹等勢分叉」等為主要害因，故未來在栽培及維護上應對此4類主要害因加以注重防範。本研究亦納入重要疫病蟲害之診治案例，包括流膠病、白蟻防治、霧社血斑天牛防治、褐根病及靈芝根基腐之防治等，另取得離體病菌利用水瓊脂平台法進行藥劑之快速防治測試，探討防治率及防治最佳策略，共完成了14個重要植物疫病蟲害診治案例報告，應可增進從業樹木醫師對田間疫病蟲害之診治能力。

關鍵字

櫻花；漆酶；木材腐朽菌；電子鼻；目視樹木評估法；健康檢查；風險評估；樹病診治

並列摘要

The blossom cherry trees belong to the genus Prunus of the Rosaceae family. They are deciduous ornamental trees with pretty blossom in the spring season that many people enjoy the blossom viewing every year. There are various cultivars of blossom cherry in Taiwan, but usually are foreign cultivars grafted on native Taiwan cherry trees. Only five cherry species are native in Taiwan, including the most popular Taiwan cherry (Prunus campanulata Maxim), P. transarisanensis Hayata, P. grisea Kalkman, P. matuurai Sasaki, and P. taiwaniana Hayata. There are six objectives of this study, including (1) the investigation on major pests and disorder factors of the blossom cherry and other common trees in northern and central Taiwan, (2) the isolation of the causal pathogens and wood rot fungi, (3) the wood decomposition enzyme assay of the isolated wood rot fungi, (4) the use of electronic nose for fast detecting of root and butt rot tree diseases, (5) the tree health examination and risk assessment with modified visual tree assessment (VTA) form, and (6) diagnosis and treatment case reports of important tree pests and disorder. The investigation on major pests and disorder factors of the blossom cherry and other common trees was focused in school campus, public park, street trees and freeway greening trees. Investigation results show that the major diseases are brown root rot (brr), Ganoderma root and butt rot, stem gummosis, Rigidoporus root and butt rot, root rot, twig blight, leaf tar spot, leaf shot hole, and magnesium deficiency. The major insect pests on trees are long-horned beetle (Hemadius oenochrous), termite, and geometrid moth (Milionia basalis). A total of 30 fungal isolates were obtained after using water ager, MA+4 medium, acidified PDA, and malt extract medium to isolate the disease pathogen or wood rot fungi from the affected trees. The cellulose decomposition enzyme assay was conducted on CMC medium for these 30 isolates. Results show that among them 12 isolates exhibit prominent CMC-decomposing ability, while 5 of them can excrete the exoenzyme. The lignin decomposition enzyme assay was based on laccase activity of the isolated wood rot fungi and conducted on pine chip-YMEA agar plate, following the newly developed method by our Laboratory. Results of laccase activity assay show that 2 among five isolates express strong laccase activity. A Cyranose 320 electronic nose was utilized for fast detecting of brown root rot, or root and butt rot tree diseases. The E-nose was trained with standard fruiting body of brown root rot fungi, then used to identify the smell from other fruiting bodies of 12 different species collected freshly from the field. Results show that the Cyranose 320 can not differentiate among brr and other 12 species of basidiomycetes, indicating that all 13 species have the same smell. The tree health examination and preliminary risk assessment were conducted on 2900 trees in school campus, sidewalk, public parks and freeway greening belts with a modified visual tree assessment (VTA) form. Results show that the major health-threatening factors are wood rot, weakness, bark defect, and codominant stem. A total of 14 diagnosis and treatment case reports were completed and focused on important tree pests and disorder, including brown root rot, Ganoderma root and butt rot, stem gumminosis, Rigidoporus root and butt rot, termite, long-horned beetle. A water agar platform method was also utilized for fast evaluation for the control rates of commercialized fungicides in Taiwan. The diagnosis and treatment practice can supply useful information for a practitioner tree doctors.