Powdery Mildew of Gerbera in Taiwan

在嘉義農業試驗分所栽培之非洲菊發現白粉病，白粉病菌的有性世代並未發現。分生孢子鏈生於孢子梗頂端，無色，單胞，短橢圓形，大小爲20~33.7×15μm (27.7×19.6μm)，含有2~10皿狀物。孢子發芽管短，單出或分叉形。根據其分生孢子特徵，可知本菌屬於Sphaerotheca fuliginea。初步調查，荷蘭Marleen、Veronica、Damco、美國Gigi Mixture等爲較易感病品種。 Powdery mildew of Gerbera jamesonii Bolus was found in February, 1990 at Chiayi, Taiwan. The sexual stage of the powdery mildew fungus in Gerbera was not found in Taiwan. Conidia are formed in chain,. ovoid, 20~33.7×15~25 μm (27.7×19.6 μm) in size, and containing fibrosin bodies. Conidia germinate with a short simple or forked germ tube. According to the characteristics of the Qidium state, Sphaerotheca fuliginea was identified as the causal agent

Application of Beneficial Microorganisms for the Control of Crop Diseases

十字花科蔬菜根瘤病於每年春、秋兩季嚴重發生於台中、新竹及桃園一帶, 夏季嚴重發生於宜蘭南山、台中武陵、福壽山、南投清境等地, 常造成農民莫大的損失, 亦造成夏季甘藍供需問題.本病原菌之休眠孢子可存活於土壤中長達10年, 不易使用藥劑防治, 目前主要的防治方法以土壤添加含鈣化物為主, 但是鈣化物必須大量施用於土壤中方能達到防治效果, 且土壤改良又易受到雨水、灌溉、施肥、土壤母質等因素影響, 而失去應有的效果.連年大量施用鈣化物亦有改變土壤性狀之虞, 既不經濟又不方便, 難為農民所樂意使用.如能利用生物防治方法, 於甘藍苗期導入具防治病害效果的拮抗微生物, 再將甘藍種苗供給農民使用, 不但具便利性又可達到防治病害的效果.內生菌根菌廣泛存在於顯花植物的根部, 根據報告指出, 內生菌根菌可以有效的防治植物根部病害, 在十字花科蔬菜根部卻比較少有內生菌根菌存在, 但是亦有學者利用Heteroconium chaetospira此一內生菌根菌防治十字花科蔬菜根瘤病成功的例子.本計畫將篩選具防治此一病害的內生菌根菌, 並導入甘藍幼苗根部, 藉以發展防治此一病害的方法.胡瓜尖鐮胞菌萎凋病在世界上任何胡瓜栽培區都是重要病害.它的病原菌Fusarium oxysporum f.sp.Cucurmerinum屬於土棲菌, 在土壤以厚膜胞子普遍存在.因此土壤消毒和輪作的防治方法是不太有用的.目前臺灣沒有抗病品種, 加上本病害困難用藥劑防治, 近年來生物防治的研究有好結果.大都是將作物幼苗先行接種無病原性尖鐮胞菌或拮抗細菌.雖然看好, 但仍未實用於田間之病害防治.本研究初步在花蓮地區發現一抑病型土壤, 可抑制胡瓜萎凋病.本計畫案擬研究該抑病土壤之抑病性質, 試從中分離並篩選無病原性尖鐮胞菌和拮抗細菌, 單獨或混合使用, 以期在溫室和田間能夠成功的防治胡瓜萎凋病.生物防治為近年來在植物保護策略上最大之改變, 由於過去農藥之過份使用所導致之環境衝擊, 使人類對非農藥之綜合防治特別是生物防治充滿期待, 由於農藥殘留的恐懼心, 使有機農法更是如日中天迅速發展, 因而微生物製劑之開發與利用成為農業上開發之重點.微生物製劑所用拮抗菌種類.在農委會經費補助下近三年來本研究室已研發成功生物防治製劑黏帚黴菌菌株GVG8, 且已辦理技術轉移, 這一生物防治製劑對數種重要病害具有優良的防治效果, 如山蘇花葉斑病、水稻紋枯病、十字花科立枯絲核菌引起之苗立枯病等.這些病害防治都經田間試驗再三測試確認, 除這些病害外將繼續測試其他重要病害, 以擴大該製劑之使用範圍, 另一方面部份製劑所用載體價格較為昂貴, 將繼續嘗試其他重要病害生物防治之可能性, 以增加這些生物防治製劑的使用範圍.木黴菌方面本研究室具有十多株具有生物防治潛力, 目前已上市木黴菌製劑都以分生孢子及菌絲體為主, 本研究室最近突破液體發酵方法, 木黴菌已可以量產完全是厚膜胞子之產品, 本計畫將選舉數株較有潛力者, 製成各種劑型, 防治重要病害如山蘇花、花生與番茄白絹病、金線連莖腐病等.本省土壤傳播性病原真菌引起的洋香瓜萎凋型病害, 包含黑點根腐病、冠腐及基腐病、立枯病等9種, 可見洋香瓜之萎凋或敗藤, 是一種多病因的病害.且不同地區之病原種類, 亦有不同.冬瓜萎凋病由下位葉開始逐漸變黃萎凋, 隨後葉柄下垂, 葉片焦枯, 整株枯萎死亡, 少數呈半邊萎凋或裂蔓現象, 後期在病蔓表面出現白色黴狀物; 受害的根部在較小的支根上出現褐化病徵; 若剖開植株縱橫切面, 維管束明顯褐變.本病在苗期及成長期均會發生, 若幼苗罹病, 可迅速萎凋死亡.至於較大植株罹病時, 則可延遲至結果期才發病.生物防治的研究, 主要是希望藉由自然界生物的力量以減少病原菌在農業生態體系中所造成的損失.亦即考慮自然生態的平衡與保育為前題, 謀求植物體的健康, 以維繫農作物原有的生產潛能.適當的使用有機添加物, 將可增加瓜田土壤中原有的微生物或人為引入之拮抗微生物; 進而強化該微生物之抑菌功能或增加作物本身的抗病能力等, 以減少作物病害的發生.為改善瓜田土壤微生物相, 有賴於能夠篩選優良拮抗微生物( microbial antagonists )菌株, 配合土壤添加物之使用, 以有效防治甜瓜與冬瓜萎凋型病害.Clubroot caused by Plasmodiophora brassicae is one of the most serious soilborne diseases of crucifers in Taiwan.The disease is mainly occurred on the cultivars of mustard, szechuan mustagd and Chinese cabbage in Taoyuan, Hsinchu and Taichung areas during the spring and the autumn seasons.Resting spores of the pathogen can survive for more than 10years in the soil and make disease-control difficult.Many fungicides, soil amendments and use of resistant cultivars have been used to control the disease but sometime with unsatisfactory results.Attempts have been made to develop biological control of clubroot by using isolate of soil fungi, soilborne bacteria or baiting crops, but none of these has proved effective under field conditions.However, the isolation method used probably selected organisms which were soil inhabitants and which may have lacked the ability to colonize the roots of host plants.It would probably be better to select potential agents for biocontrol of clubroot from those able to colonize root.Epiphytic, endophytic or mycorrhizal fungi are clearly superior to external rhizosphere or soil fungi in the ability to colonize root.Mycorrhyzas are known to be effective in inhibiting the development of pathogens and reducing incidence of the disease.Although most plant species, including a large number of crops, can develop mycorrhizas, Cruciferae is an exceptional plant family, with few or no mycorrhizas.This experiment will test the isolation of Root-colonizing fungi from Chinese cabbage root, and appraise their ability to suppress clubroot.Fusarium wilt is one of the most prevalent and damaging disease of cucumber wherever cucumber are grown intensively.The pathogen, Fusarium oxusporum f.sp.Cucurmerinum, is a soil inhabitant.The fungus is so widespread and so persistent in soils that seedbed sterilization and crop rotation are of limited value.Resistant variety of cucumber to this fungus is not available in Taiwan.Moreover, it is very difficult to control by chemicals either.Therefore, in the last several years biological control of fusarial wilt has given encouraging results.Control may involve prior inoculation of plants with formae specialis of F.oxysporum not pathogenic to each crop or the use of antagonistic Pseudomonads.Although promising, none of them is used for practical control of fusarial wilts so far.In our preliminary experiments, a soil obtained from Hwa-Liang area was found to be suppressive to the Fusarium wilt of cucumber.In this project, we propose to study the nature of its suppressiveness.Isolates of non-pathogenic F.oxysporum and antagonistic bacteria will be isolated and screened for their antagonistic effect to the pathogen and will be used alone or mixed together to control this disease in greenhouse and field.Biocontrol is a big change in plant protection strategy recently.The large impact to our environments caused by over usage of chemical pesticides is realized.As consequence people are expecting non-chemical integrated pest control especially biocontrol.Due to the chemical residue in agricultural products, organic farming becomes very important to many consumers.Therefore development and use of microbial formulations become main issue in agricultural policy.There are many microorganisms used as antagonists, i.e., Trichoderma spp., Bacillus subtilis, fluorescent Pseudomonads, Streptomyces spp.etc.At present about 40-biocontrol formulation products are in market for disease control.Among them at least 12are belonging Trichoderma, i.e., Bio-Fungus, Binab-T, RootShield, Supresivit, T-22G, T-22HB, Trichodex, Trichopel, Trichoseal, Trichoject, Trichodowels, Trichoderma 2000used to control Botrytis, Fusarium, Gaeumannomyces, Pythium, Rhizoctonia, Sclerotinia, Sclerotium, Verticillium and wood rot fu

Development of Integrated Management Technology for the Control of Plant Diseases and Pests (II)

本計畫主要針對花卉、果樹和蔬菜等重點發展作物上所發生之重要病蟲害,研究其病原或蟲害之特性、發生生態、分類地位與診斷鑑定方法技術,繼而研擬整合性綜合防治管理技術,以減輕病蟲威脅,提升各項作物之競爭力與農民所得.另外,改進非農藥防治技術,提升其效果以增進農民實際應用之意願,期能降低農藥使用,維護生態環境平衡,符合永續經營之目標.在實際之執行面上,將著重於下列目標: I. 研發花卉作物種苗傳播之新病害鑑定及診斷技術,協助業者規劃合理去除病原菌之流程,以建立健康種苗供應體系.進一步瞭解各項病害之發生生態,並篩選適合之防治藥劑及其他無農藥之防治方法以達綜合防治目標.本項目今年度涵蓋彩色海芋軟腐病、白鶴芋根腐葉班病、文心蘭切花花梗腐敗病和火鶴花花腐病等. II. 探討柑桔黑點病及蓮霧果腐病之發生生態,改進其農藥之合理使用並開發無農藥之防治方法. III. 研發蔬菜之重大病害之綜合管理方式,尤其著重於無農藥之防治方法,包括抗病育種和抗病根砧之利用等.本項目今年度涵蓋穴盤蔬菜病害、瓜類作物萎凋病和蕃茄晚疫病等. IV. 以分子生物技術研發各種病害之核酸探針,供病害快速診斷之應用.本項目今年度涵蓋楊桃細菌性斑點病、穴盤蔬菜立枯病和露菌病等.This project is aimed at the devastating disease and pest problems of important crops, including ornamental flowers, fruit trees and vegetables in Taiwan. The major framework of this study is to reveal the characteristics, taxonomic status and ecology of each pathogen and pest, to establish quick and precise diagnosis technology, and to develop effective control measures or the integrated pest management system. The attempt of this study is also to create or improve the non-chemical control measures for the diseases and pests in order to reduce the chemical residues in agricultural products, to preserve the balance of ecological environment and consequently to reach the goal of substantial agriculture system. The main research items of this year are as follow: I. To study the diseases that are disseminated through vegetative propagation procedure of ornamental flowers, to develop the indexing kits techniques, to establish pathogen-free propagation system for some of the economically important ornamental crops such as colored calla lily, Cylindrocladium root and petiole rot of pease lilies, the bacterial peducle rot of Oncidium and Anthurium spathe blight. II. To establish a more comprehensive IPM system for citrus black spot and fruit diseases of waxapple. III. To study the integrated control measures of vegetable diseases, especially sreeening for resistant varieties, resistant rootstocks and other non-chemical control measures. The target diseases for this fiscal year include tomato late blight, Fusarium wilt of cucurbitaceous plants, and black spot and root rot of muskmelon. IV. To develop DNA probes and proper PCR procedures for Rhizoctonia solani, downy mildew fungi and Pseudomonas syringae