| 摘要： 番石榴立枯病由Myxosporium psidii Sawada et Kurosawa所引起, 為台灣特有之病害.目前在全省各種植區, 病株到處可見; 當發病率達30%以上時, 即須廢園, 以免病情擴大.由於病原菌須經由傷口感染入侵, 目前病害防治之方法著重於病株及傷口處理等田間衛生及管理措施.但由於番石榴之栽培須不定期地進行修剪及摘心等工作, 所以病害始終無法完全根除.為了對該病害做更有效之防治管理, 減低目前存在之損失及避免其對番石榴生產之潛在威脅, 本計畫乃希望藉由田間病原菌及拮抗菌之分離與篩選, 尋找較為有效之生物防治策略, 以降低該病害造成之損失.該計畫之主要目標為1.田間病原菌之分離, 進行生理及病原特性之研究, 以期找出弱病原性之病原菌, 進行其弱病原性成因之探討( 如於chestnut blight, 因dsRNA感染所造之弱病原性現象 ).若其成因可茲進行開發, 將作為發展生物防治之用.2.由田間植株進行拮抗菌之分離, 並利用對峙培養進行測試.重要工作項目為: ( 1 )進行全省番石榴栽培區病原菌之分離.( 2 )分離所得之菌株將進行生理及病原特性等之分析, 並利用分子生物相關技術, 發展出種內親緣鑑定系統.( 3 )若獲致弱病原性之病原菌, 將進行其成因之探討, 是否有因dsRNA之感染所造成之弱病原性現象, 如chestnut blight.( 4 )若有dsRNA感染所造成之弱病原性之病原菌, 檢視是否可經由菌絲融合, 將dsRNA傳給強病原性之病原菌, 造成弱病原性.( 5 )田間拮抗菌之分離, 並利用對峙培養進行拮抗作用之測試。Guava Myxosporium wilt or guava Likubin, caused by Myxosporium psidii Sawada et Kurosawa, is one of the devastating diseases of guava ( Psidium guajava L. )in Taiwan.This endemic disease was first reported by Kurosawa in 1926and has not been recorded in other guava growing countries.The disease occurs all over the orchards in Taiwan.When the disease incidence is over 30%, the field has to be abandoned.The pathogen invades through the wound sites, and then spreads systemically via xylem vessels.The current control measures are rogueing of diseased trees and treating the open wounds with fungicides.But due to the special culture practices like trimming, pruning to prolong the harvest season, the occurrence of the disease has always resulted in certain amount of yield loss.In order to control the disease more effectively and minimize the potential threat, we propose a bio-control approach and hope to provide an alternative tool for current control measures.Two main goals will be focused in this proposal.First, the causing fungus will be isolated from different guava growing fields and analyzed their physiological and pathogenic characters.The isolate( s )with abnormal physiological traits or reduced virulence will be examined.The cause ( like hypovirulence in chestnut blight fungus )will be further explored to develop to a new bio-control tool.Second, we will try to isolate the antagonist microorganisms from the field and access the antagonized ability to the causing fungus.This approach will hopefully provide another bio-control possibility. |
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