Dissertations / Theses on the topic 'Biofungicidas'

Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia<br>The Lupinus genus had its origin in the Mediterranean basin and in North Africa, with existing records of its cultivation in Egypt about 4000 years ago. The four main species of the Lupinus genus in the world are L. albus, L. angustifolius, L. luteus and L. mutabilis, being Australia the world biggest producer. The main reasons for its cultivation are human consumption, green manure, animal feed and its use as a protein supplement. The discovery of a polypeptide extracted from cells of the germinated cotyledons with antifungal properties and biostimulant ability created an innovative application for lupine: the production of a biofungicide. Damage of the cotyledonary tissue led to a decrease in protein content available for extraction. Germination of a sweet variety in the presence of bitter seeds suggested that there was an increase in the amount of protein available for extraction from sweet seeds. It was possible to obtain a concentrated extract by clarifying the extract using a thermal fractionation method. The concentrated extract was combined successfully with a number of surfactant agents, from which the most appropriate were chosen according to wetting and spreadability properties and to the concept of a non-synthetic biofungicide. The formulated extract showed a strong buffering capacity and a high resistance to stress factors such as temperature and agitation during an eight week period. Evaporation proved to be an adequate method of concentration at pilot scale as an alternative to laboratory-scale freeze-drying. The production of a concentrated extract with 20% (w/w) protein was possible through the extract concentration with tree single step evaporations. The first two were separated by a thermal fractionation. Between the second and the third evaporation there was a resting period at cold temperature, centrifugation and formulation process of the product. It has been shown the existence of more suitable varieties of Lupinus for large scale production of concentrated extract, being the most appropriate of the three studied the Amiga variety.

Senegal ranks second for mango production among West African countries and has the potential to competitively produce mangoes for the European market. Colletotrichum gloeosporioides Penz. and Sacc. has historically been considered the causal pathogen of anthracnose of mango and other fruits, but is now known to represent a species complex. Field trials to examine the efficacy of fungicides and biofungicides were conducted in southern and northern production regions of Senegal. In three southern trials, Sonata (Bacillus pumilus strain QST 2808), Serenade Optimum (Bacillus subtilis strain QST 713), and sodium molybdate provided 63%, 67% and 76% control of disease severity, respectively, whereas thiophanate methyl and azoxystrobin provided 77% and 78% control, respectively. Disease severities of all treatments were significantly lower than that of the control. Thiophanate methyl and azoxystrobin produced more disease-free mangoes (64 and 62%, respectively) than Serenade (49%), sodium molybdate (44%), and Sonata (38%). Differences within each trial were not statistically significant, but when all trials were combined, all treatments resulted in significantly more disease-free mangoes than the control. Among treatments, thiophanate methyl and azoxystrobin resulted in significantly more disease-free mangoes than Sonata. No results were obtained in the northern orchards due to an absence of disease development. Sequencing of the ITS gene region of 30 Colletotrichum isolates from mangoes from different regions in Senegal indicated that all belonged to the C. gloeosporioides species complex. Sequencing of the ApMat intergenic region identified all of them as most closely resembling C. siamense.<br>Master of Science in Life Sciences

Made available in DSpace on 2014-06-11T19:29:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-01-18Bitstream added on 2014-06-13T19:17:16Z : No. of bitstreams: 1 pedro_ro_me_sjrp_parcial.pdf: 308733 bytes, checksum: 9891c3253677398a2eaeee4aa835dae4 (MD5) Bitstreams deleted on 2015-02-09T14:35:39Z: pedro_ro_me_sjrp_parcial.pdf,Bitstream added on 2015-02-09T14:36:20Z : No. of bitstreams: 1 000713827.pdf: 1107831 bytes, checksum: 7123832b50b5229b5f6397201b89b8a2 (MD5) Bitstreams deleted on 2015-02-09T17:15:02Z: 000713827.pdf,Bitstream added on 2015-02-09T17:15:39Z : No. of bitstreams: 1 000713827.pdf: 1107831 bytes, checksum: 7123832b50b5229b5f6397201b89b8a2 (MD5)<br>Os fungos do gênero Aspergillus, presentes em amendoins, milho, arroz, nozes e outros grãos, são uma constante preocupação nos dias atuais devido a sua capacidade de produzir toxinas cancerígenas. Dentre as várias técnicas de controle desse microrganismo, tem se destacado o uso de produtos naturais, não agressivos ao meio ambiente e de baixo custo, como por exemplo, a quitosana. O presente trabalho apresenta a síntese e caracterização de duas séries de novos derivados de quitosana para utilização como biofungicida contra os fungos Aspergillus flavus e Aspergillus parasiticus. A primeira série descreve a síntese de derivados de quitosana pela reação de quitosana desacetilada (QD) com brometo de propil (Q-Propil) pentil (Q-Pentil) trimetilamônio para obter derivados com proporções crescentes do grau de substituição (GS). A segunda série foi obtida a partir da síntese de sais bi-quaternários de amônio, com a posterior reação com quitosana desacetilada obtendo-se derivados bi-quaternários de quitosana. Todos os derivados foram caracterizados por técnicas de RMN 1 H, infra-vermelho (IR) e titulação potenciométrica e as suas atividades fungicidas testadas contra o crescimento micelial dos fungos A. flavus e A. parasiticus in vitro. Os estudos foram conduzidos variando-se a acidez e a força iônica do meio. Os resultados dos ensaios microbiológicos mostram que as atividades antifúngicas aumentam com o grau de substituição e os derivados mais substituídos de ambas as series, propil e pentil, exibiram respectivamente atividades três e seis vezes maiores que as quitosanas comercial e desacetilada. As concentrações inibitórias mínimas foram avaliadas após 24, 48 e 72 horas, variando-se a concentração dos polímeros de 0,5 a 16 g L -1 e os resultados mostraram que os derivados quaternários inibem o crescimento...<br>The fungi of the genus Aspergillus, present in peanuts, corn, rice, nuts and other grains, are a constant concern nowadays due to its ability to produce carcinogenic toxins. Among the various techniques for controlling this microorganism it has been emphasized the use of natural products not harmful to the environment and at a low cost, for example, chitosan. This paper presents the synthesis and the characterization of two series of novel derivatives of chitosan for use as biofungicide against the Aspergillus flavus and Aspergillus parasiticus fungi. The first series of derivatives was synthesized by the reaction of deacetylated chitosan (QD) propyl bromide (Q-Propil) and pentyl trimethylammonium (Q-Pentil) for obtaining derivatives with increasing degrees of substitution (GS). The second series was obtained from the synthesis of bi-quaternary salts, with subsequent reaction with deacetylated chitosan to yield bi-quaternary derivatives of chitosan (Q-BPHD). All derivatives were characterized using NMR techniques, infra-red (IR) and potentiometric titration and fungicides activities were tested against A. flavus and A. parasiticus by evaluating the mycelial growth of fungi in vitro. The studies were conducted by varying the acidity and ionic strength of the medium. The antifungal activities increase with the degree of substitution and the most substituted derivatives from both series, propyl and pentyl, respectively exhibited activities three to six times lighter than the commercial and deacetylated chitosans. The minimum inhibitory concentrations were recorded after 24, 48 and 72 hours varying the concentration of polymer from 0.5 to 16 g L -1 and the results showed that the quaternary derivatives inhibit the growth of fungi in concentrations four times lower than deacetylated chitosan . The bi-quaternary derivative (Q-BPHD) showed the... (Complete abstract click electronic access below)

Orientador: Vera Aparecida de Oliveira Tiera<br>Banca: Éder Tadeu Gomes Cavalheiro<br>Banca: Marcelo de Freitas Lima<br>Resumo: Os fungos do gênero Aspergillus, presentes em amendoins, milho, arroz, nozes e outros grãos, são uma constante preocupação nos dias atuais devido a sua capacidade de produzir toxinas cancerígenas. Dentre as várias técnicas de controle desse microrganismo, tem se destacado o uso de produtos naturais, não agressivos ao meio ambiente e de baixo custo, como por exemplo, a quitosana. O presente trabalho apresenta a síntese e caracterização de duas séries de novos derivados de quitosana para utilização como biofungicida contra os fungos Aspergillus flavus e Aspergillus parasiticus. A primeira série descreve a síntese de derivados de quitosana pela reação de quitosana desacetilada (QD) com brometo de propil (Q-Propil) pentil (Q-Pentil) trimetilamônio para obter derivados com proporções crescentes do grau de substituição (GS). A segunda série foi obtida a partir da síntese de sais bi-quaternários de amônio, com a posterior reação com quitosana desacetilada obtendo-se derivados bi-quaternários de quitosana. Todos os derivados foram caracterizados por técnicas de RMN 1 H, infra-vermelho (IR) e titulação potenciométrica e as suas atividades fungicidas testadas contra o crescimento micelial dos fungos A. flavus e A. parasiticus in vitro. Os estudos foram conduzidos variando-se a acidez e a força iônica do meio. Os resultados dos ensaios microbiológicos mostram que as atividades antifúngicas aumentam com o grau de substituição e os derivados mais substituídos de ambas as series, propil e pentil, exibiram respectivamente atividades três e seis vezes maiores que as quitosanas comercial e desacetilada. As concentrações inibitórias mínimas foram avaliadas após 24, 48 e 72 horas, variando-se a concentração dos polímeros de 0,5 a 16 g L -1 e os resultados mostraram que os derivados quaternários inibem o crescimento... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The fungi of the genus Aspergillus, present in peanuts, corn, rice, nuts and other grains, are a constant concern nowadays due to its ability to produce carcinogenic toxins. Among the various techniques for controlling this microorganism it has been emphasized the use of natural products not harmful to the environment and at a low cost, for example, chitosan. This paper presents the synthesis and the characterization of two series of novel derivatives of chitosan for use as biofungicide against the Aspergillus flavus and Aspergillus parasiticus fungi. The first series of derivatives was synthesized by the reaction of deacetylated chitosan (QD) propyl bromide (Q-Propil) and pentyl trimethylammonium (Q-Pentil) for obtaining derivatives with increasing degrees of substitution (GS). The second series was obtained from the synthesis of bi-quaternary salts, with subsequent reaction with deacetylated chitosan to yield bi-quaternary derivatives of chitosan (Q-BPHD). All derivatives were characterized using NMR techniques, infra-red (IR) and potentiometric titration and fungicides activities were tested against A. flavus and A. parasiticus by evaluating the mycelial growth of fungi in vitro. The studies were conducted by varying the acidity and ionic strength of the medium. The antifungal activities increase with the degree of substitution and the most substituted derivatives from both series, propyl and pentyl, respectively exhibited activities three to six times lighter than the commercial and deacetylated chitosans. The minimum inhibitory concentrations were recorded after 24, 48 and 72 hours varying the concentration of polymer from 0.5 to 16 g L -1 and the results showed that the quaternary derivatives inhibit the growth of fungi in concentrations four times lower than deacetylated chitosan . The bi-quaternary derivative (Q-BPHD) showed the... (Complete abstract click electronic access below)<br>Mestre

Made available in DSpace on 2016-08-12T19:15:42Z (GMT). No. of bitstreams: 1 Renata DamascenoMoura.pdf: 1585836 bytes, checksum: 46aa646391a0b24176cc1eebf422215a (MD5) Previous issue date: 2007-05-05<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>The aim this study was to evaluate the effect of the application of biological, alternative and chemical products on the control of postharvest diseases and conservation of Cantaloupe melon. In the control experiment in vitro (Test of Antagonist) was verified the ocorrence of antagonistic between isolates of Trichoderma (SN11, T15, T25, TR2) with relation the all pathogenic isolates to melon (Fusarium sp, Aspergillus niger, Aspergillus flavus, Rhizopus stlonifer and Lasiodiplodia theobromae). For the treatments, the most effective in the inhibition of the fungi mycelial growth were the nature fungicide 20 mL-1 and Lippia sidoides, that were effectives in 100% to all evaluated fungi; the Cymbopogum citratus was only less effective on the A. flavus fungi (75,3%) and the Imazalil fungicide has lower efficiency on the R stolonifer fungi (1,54%). The treatment with nature fungicide 2mL-1 has higher efficiency in relation to Fusarium sp and L. theobromae, with inhibitions of 88,9 and 86,2% respectively, and lower efficciency on the R. stolonifer (3,3%). In assay in vivo it was used split spot in a completely randomized design, with three replicates and three fruits for treatment. In the spots were alloted the periods of storage (0, 7, 14, 21 and 28 days) and the subplots, the treatments (Trichoderma + hipoclorito), (Trichoderma without hipoclorito), (nature fungicide 20 mL-1), (nature fungicide 2 mL-1), (essential oil of Cymbopogum citratus 2 mL-1), (essential oil of Lippia sidoides 2 mL-1), (Chemical Imazalil 1 mL-1) and (Control - application of destiled water). After the treatments, the fruits were conservated in boxes of paper, it using modify atmosphere with poliméricos films xtend and stored in a temperature of 6°C and UR 90±5%. The fruits were evaluated with relation to incidence of diseases, external and internal appearences, color, loss of matter fresh, pulp firmness, soluble solids, total soluble sugar, pH and titritable total acidity at 7, 14, 21 and 28 days after the period of storage of three days at 22º C ± 2º C and UR of 50% ± 5%. It was observed significant interation between treatments and storage time for occurence of disease, extern and intern appearence, color, titritable total acidity, pH and soluble solids. For the variable loss of fresch mass, it was verified that the treated fruits with nature fungicide 20 and 2 mL.L-1, Lippia sidoides and Cymbopogum citratus presented lower values, did not differing between them nor of the treatment with destiled water. The pulp firmness of treated fruits with Trichoderma (T1) presented value of 26,19 N and differed only of Trichoderma without hipoclorito (T2) and Cymbopogum citratus (T5), that showed fruits less firm (20,51 and 22,72 N, respectively). There was not statistical difference between treatments for the variables: soluble solids and total soluble sugar. The nature fungicide 20 mL1 Trichoderma with hipoclorito, Lippia sidoides and Imazalil were the treatments most effectives in the control of postharvest diseases of Cantaloupe hybrids melon ( Hy Mark )<br>Objetivou-se estudar o efeito da aplicação de produtos biológicos, alternativos e químicos no controle de doenças pós-colheita e conservação de melões Cantaloupe. No ensaio de controle in vitro (Teste de Antagonismo) foi possível verificar a ocorrência de antagonismo entre os isolados de Trichoderma (SN11, T15, T25, TR2) em relação a todos os isolados patogênicos ao melão (Fusarium sp, Aspergillus niger, Aspergillus flavus, Rhizopus stlonifer e Lasiodiplodia theobromae). Quanto aos tratamentos os mais efetivos na inibição do crescimento micelial dos fungos foram o fungicida natural a 20. mL-1, e alecrim pimenta nos quais foram efetivos em 100% para todos os fungos avaliados, o capim citronela foi apenas menos efetivo sobre o fungo A. flavus (75,3%) e o fungicida Imazalil teve menor eficiência sobre o fungo R stolonifer (1,54%). O tratamento com fungicida natural a 2 mL-1teve maior eficiência em relação aos fungos Fusarium sp e L. theobromae, com inibições de 88,9 e 86,2 % respectivamente, e menor eficiência sobre o fungo R. stolonifer (3,3%). Para o experimento in vivo o delineamento experimental utilizado foi o inteiramente casualizado em parcelas subdivididas com três repetições e três frutos por tratamento. Nas parcelas foram alocados os períodos de armazenamento (0, 7, 14, 21, 28 dias) e nas subparcelas os seguintes tratamentos (Trichoderma + hipoclorito), (Trichoderma sem hipoclorito), (fungicida natural 20 mL-1), (fungicida natural 2 mL-1), (óleo essencial de capim citronela 2 mL-1), (óleo essencial de alecrim pimenta 2 mL-1), (Químico Imazalil 1mL-1) e (Testemunha- aplicação de água destilada). Após os tratamentos os frutos foram acondicionados em caixas de papelão, usando-se também atmosfera modificada com filmes poliméricos x-tend e armazenados sob refrigeração com temperatura de 6°C e UR 90±5%. As avaliações nos frutos foram realizadas para avaliação de doenças, aparência externa e interna, cor, perda de matéria fresca, firmeza de polpa, sólidos solúveis, açúcares solúveis totais, pH e acidez titulável realizadas a 7, 14, 21, e 28 dias após o período de prateleira de três dias a 22º C ± 2º C e UR de 50% ± 5%. Observou-se, interação significativa entre os tratamentos e o tempo de armazenamento para incidência de doença, aparência externa e interna, cor, acidez titulavel, pH, na relação sólidos solúveis e acidez titulavel. Para variável perda de massa fresca verificou-se que os frutos tratados com fungicida natural 20 e 2 mL.L-1, alecrim pimenta e capim citronela apresentaram os menores valores de perda de massa fresca, não diferindo entre si e nem do tratamento com água. Para firmeza de polpa frutos tratados com Trichoderma (T1) apresentaram firmeza entorno de 26,19 N, diferindo apenas de Trichoderma sem hipoclorito (T2) e capim citronela (T5) que proporcionaram frutos menos firmes 20,51 e 22,72 N respectivamente. Não foi observada diferença estatística entre os tratamentos pelo teste Tukey para as variáveis sólidos solúveis e açúcares solúveis totais. Os tratamentos que se mostraram mais efetivos no controle de doenças em pós-colheita do melão Cantaloupe híbrido Hy Mark foram fungicida natural a 20 mL1,Trichoderma com hipoclorito, alecrim pimenta e Imazalil

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-09-06T18:21:23Z No. of bitstreams: 1 2017 - Carlos Ant?nio dos Santos.pdf: 1589290 bytes, checksum: fbf16019cb63898c65e615c045d17094 (MD5)<br>Made available in DSpace on 2018-09-06T18:21:23Z (GMT). No. of bitstreams: 1 2017 - Carlos Ant?nio dos Santos.pdf: 1589290 bytes, checksum: fbf16019cb63898c65e615c045d17094 (MD5) Previous issue date: 2017-02-17<br>CAPES<br>CNPq<br>FAPERJ<br>The search for efficient strategies to reduce the losses caused by clubroot (Plasmodiophora brassicae) in cauliflower is essential due to the economic and social importance of this culture. Thus, the present study was developed with the objective of evaluating the effect of different treatments in the control of the disease, root development, biomass and inflorescences production under field and greenhouse conditions. The study consisted of three trials carried out in a family farmer's area in the municipality of Nova Friburgo, RJ, Brazil. In the first trial, it was tested the residual effect of four doses of calcined limestone (0, 1.0, 2.0 and 4.0 Mg.ha-1) associated to the application of Trichoderma harzianum biofungicide under field conditions. In the second trial, it was tested the effect of the liming associated to the application of T. harzianum and cyazofamid, under greenhouse conditions. In the third one, two ways of applying limestone were tested, in the planting pit, and applied by hand. The use of gypsum was evaluated in the field. The increase of the limestone doses promoted higher pH levels, and Ca+2 contents, and reduction of the toxic Al + 3 contents in the soil. There was also a reduction of root volume with galls, greater root development, and productivity in cauliflower. The use of T. harzianum was not effective to control the disease and did not favor the root development, either in field or in greenhouse conditions. The fungicide cyazofamid reduced the volume roots with galls, the severity, and the progression of the disease. The third rial revealed a discrete reduction in the severity of the disease when using limestone and gypsum combined. Although there was no effect of the treatments on the root system, limestone applied to the pit and by hand resulted in greater accumulations of fresh mass of inflorescence and productivity. The application of limestone by hand, in the pit, and combined with gypsum favored the accumulation of calcium in the plants. The application of limestone in the pit was equivalent to the hand application in terms of soil chemical attributes improvement, reduction of disease severity, and increase of productivity and accumulation of nutrients.<br>A busca por estrat?gias eficientes na redu??o das perdas causadas pela h?rnia das cruc?feras (Plasmodiophora brassicae) em couve-flor ? essencial devido ? import?ncia econ?mica e social dessa cultura. Com isso, desenvolveu-se o presente estudo com o objetivo de avaliar, em condi??es de campo e casa de vegeta??o, o efeito de diferentes tratamentos no controle da doen?a, desenvolvimento das ra?zes e produ??o de biomassa e infloresc?ncias em couve-flor. O trabalho foi constitu?do de tr?s ensaios realizados em ?rea de produtor familiar no munic?pio de Nova Friburgo, RJ. No primeiro ensaio, avaliou-se o efeito residual de quatro doses de calc?rio calcinado (0; 1,0; 2,0 e 4,0 Mg.ha-1), associado ? aplica??o de biofungicida a base de Trichoderma harzianum, em condi??es de campo. No segundo, avaliou-se o efeito da calagem associada ? aplica??o de T. harzianum e ciazofamida, em casa de vegeta??o. No terceiro, avaliou-se em campo duas formas de aplica??o de calc?rio, na cova e ? lan?o, e o uso de gesso agr?cola. O aumento das doses de calc?rio promoveu eleva??o do pH e dos teores de Ca+2 e redu??o do teor de Al+3 t?xico no solo. Ainda, houve redu??o do volume de ra?zes com h?rnias e maior desenvolvimento radicular e produtividade em couve-flor. O uso de T. harzianum n?o foi eficaz no controle da doen?a e n?o favoreceu o desenvolvimento radicular das plantas, seja nas condi??es de campo ou de casa de vegeta??o. O fungicida ciazofamida reduziu o volume de ra?zes doentes, a severidade e a progress?o da doen?a. Constatou-se no terceiro ensaio discreta redu??o da severidade da doen?a com o uso de calc?rio combinado com gesso. N?o houve efeito dos tratamentos sobre o sistema radicular, entretanto, calc?rio aplicado na cova e ? lan?o resultaram em maiores ac?mulos de massa fresca de infloresc?ncia e produtividade. A aplica??o de calc?rio ? lan?o, na cova, e calc?rio combinado com gesso favoreceram o ac?mulo de c?lcio nas plantas. O uso de calc?rio na cova foi equivalente ? sua aplica??o ? lan?o quanto a melhorias dos atributos qu?micos do solo, redu??o da severidade da doen?a, aumento da produtividade e ac?mulo de nutrientes.

Mestrado em Engenharia Agronómica - Hortofruticultura e Viticultura - Instituto Superior de Agronomia<br>A botriosferiose e a escoriose são doenças do lenho que estão bastante disseminadas nas vinhas da região do Alentejo causando elevados estragos e prejuízos quer na produção anual quer na longevidade das vinhas. O objetivo desta dissertação foi o estudo da eficácia biológica de dois produtos comerciais (fungicida e biofungicida) para o controlo destas doenças. Foram escolhidos dois talhões da casta Trincadeira plantadas em 2011 que se diferenciavam apenas pelo sistema de condução (Guyot e cordão bilateral com poda mista)<br>N/A

La septoriose, causée par le champignon hémibiotrophe Zymoseptoria tritici, est l’une des maladies les plus préjudiciables sur les cultures de blé, responsable de pertes de rendement pouvant atteindre 50%. La lutte contre cette maladie repose essentiellement sur l’utilisation des fongicides conventionnels et, dans une moindre mesure, sur le recours aux ressources variétales. Toutefois, en raison des résistances développées par l’agent pathogène vis-à-vis de ces leviers et d’une demande sociale croissante pour limiter l’utilisation des intrants chimiques en agriculture, des alternatives agroécologiques, comme le biocontrôle, doivent être développées. L’objectif de ce présent projet de thèse se situe dans ce contexte et vise à identifier des composés de biocontrôle efficaces sur le pathosystème blé-Z.tritici et de caractériser leurs modes d’action. Tout d’abord, un criblage in vitro d’un panel de 181 composés microbiens (extraits fongiques ou bactériens, rhamnolipides, lipopeptides, etc.) a été réalisé pour évaluer leur activité antifongique directe vis-à-vis de l’agent pathogène. Les composés les plus actifs ont ensuite été sélectionnés pour vérifier leur efficacité de protection in planta. Une étude de relation structure-activité a été menée avec 19 rhamnolipides (RL) et a révélé que ceux présentant des liaisons ethers ou esters, avec une chaine carbonée hydrophobe de 12 carbones, sont les plus efficaces pour toutes les activités biologiques testées (activité biocide, élicitation des défenses du blé et efficacité de protection). Parmi eux, le Rh-Est-C12 s’est montré le plus prometteur, avec une efficacité de protection de 78,9%. Le potentiel de ce RL, ainsi que de la mycosubtiline, un lipopeptide efficace pour protéger le blé contre Z. tritici, pour stimuler les défenses du blé, a été étudié à l’aide d’une approche combinée de transcriptomique et de métabolomique. Le RL n’a pas déclenché de modifications majeures de la physiologie foliaire de blé ; celui-ci protégerait donc l’hôte principalement via son activité directe vis-à-vis du champignon, alors que la mycosubtiline semble présenter un mode d’action double, basé sur l’activité antifongique directe et la potentialisation des défenses du blé. Cette induction des défenses pourrait résulter de l’interaction de la mycosubtiline avec les membranes cytoplasmiques du blé, conduisant à une accumulation de flavonoïdes dans les feuilles, mais aussi à d’autres réponses dépendantes de la voie de l’acide abscissique. Ces travaux ont par ailleurs permis de mettre en évidence de nouveaux mécanismes dans les réactions de défense du blé vis-à-vis de Z. tritici. Enfin, deux nouvelles souches isolées de Bacillus velezensis ont présenté une activité antifongique prometteuse contre l’agent pathogène, résultant probablement de la production de lipopeptides, comme la baccilomycine D, dont l’activité sur Z. tritici mériterait d’être explorée<br>Septoria Tritici Blotch, caused by the hemibiotrophic fungus Zymoseptoria tritici, is one of the most severe diseases on wheat, responsible for yield losses up to 50%. Currently, strategies used to control this disease rely mainly on the use of chemical fungicides, and to a lower extent, on the use of partially resistant cultivars. Nevertheless, because of the pathogen resistances and an increasing social demand to reduce conventional pesticides in agriculture, new agroecological alternative crop protection methods, like biocontrol, must be developed. The main purpose of this thesis project was, therefore, to identify new effective biocontrol compounds on the wheat-Z. tritici pathosystem and to decipher their modes of action. An in vitro screening of a panel of 181 microbial compounds (fungal and bacterial extracts, rhamnolipids, lipopeptides…) was performed to assess their antifungal activity towards the pathogenic agent. The most active compounds were selected for further experiments, such as verifying their protection activity in planta. The ability of 19 rhamnolipids (RLs) to control the pathogen was explored and a structure-activity relationship study revealed that bioinspired RLs with ether or ester links and a 12 carbon hydrophobic fatty acid tail were the most effective for all tested biological activities (biocide activity, wheat defense elicitation and protection efficacy). Among them, Rh-Est-C12 was the most promising compound, with a protection efficacy of 78.9%. The potential of Rh-Est-C12 as well as mycosubtilin, a lipopeptide also effective to protect wheat against Z. tritici, to induce host defenses was investigated using a combined transcriptomic and metabolomic approach. The RL did not trigger any major disorganization of the wheat leaf physiology, hence it would protect the host mainly through its direct activity towards Z. tritici while mycosubtilin would display a dual mode of action, antifungal effect and wheat priming. Mycosubtilin could prime wheat by interacting with its plasma membranes leading to flavonoids accumulation and other abscisic acid dependent responses. New insights in wheat defense mechanisms towards Z. tritici were reported. Finally, two Bacillus velezensis strains, isolated from wheat phyllosphere, displayed promising antifungal effect towards the pathogenic agent. Characterization of their metabolites was performed and the putative role of bacillomycin D molecule family as a potent Z. tritici antifungal lipopeptide was highlighted

Management of clubroot caused by the soil-borne biotrophic plant protist Plasmodiophora brassicae on canola and other Brassica crops is an important challenge to producers. Studies on the interaction of pH and temperature on root hair infection (RHI) and clubroot symptom development in canola roots revealed that high levels of clubroot can occur under optimum temperature, moisture and spore load, even at alkaline pH of 7.5. Clubroot was suppressed at all temperatures at pH 8.0, but not totally eliminated. The occurrence of maximum levels of root hair infection and clubroot development (RHI = 61%, Clubroot incidence (CI) & Disease severity index (DSI) = 100%) at temperatures of 20° and 25°C and pH of 5.0 to 6.5 was confirmed. The efficacy of biofungicides against P. brassicae was influenced by pathogen load, host, growth media and its properties. Drench application of Serenade and Prestop were moderately effective in reducing clubroot levels in canola (Brassica napus L. and B. rapa L.) and to a lesser extent in Shanghai pak choy (B. rapa L. ssp. Chinensis (Rupr.) var. communis Tsen and Lee). The mean clubroot incidence and severity caused by Pathotype 3 was found to be slightly higher than that of Pathotype 6. Clubroot level increased with increase in soil bulk density.

碩士<br>國立屏東科技大學<br>農企業管理系<br>94<br>Biofungicides, a microbial product that can suppress or kill the microorganisms which cause the plant disease. In relation to the research of the biological bactericide, scholars used to focus on the study of present situation analysis and vision of the future of biological agriculture chemicals in the past, but the biological bactericide purchasing behavior of farmers was seldom probed into. Objectives of this study was to understand the biofungicides consuming behavior of vegetable farmers through their life styles, partialities for product attributes, and demographic parameters. Farmers from vegetable production and selling classes of Pingtung villages and towns were selected as the studying parent. Questionnaires which adopted descriptive statistics, faith and efficiency analysis, factor analysis, grouping analysis, ANOVA table and chi-square test, were granted 400 copies altogether. Some important results of this research are concluded as follows: Relationships among demographic parameters, purchasing patterns and partialities of product attributes were significantly correlated. Farmers with various life styles had different attitudes to biofungicides in purchasing willingness, and those who have a taste of what is just in season changes were the most heavy purchasers. Purchasing willingness was influenced by the product attributes, and “functional attribute” plays the major role in repurchasing willingness.

碩士<br>國立高雄師範大學<br>生物科技系<br>100<br>Six different fungal isolates were obtained from disease branches and fruits of mango in this study. Six fungal isolates were examined and identified by microscope and comparison with ribosomal DNA internal transcribed spacers (ITS) sequences in GenBank of NCBI. F6 isolate cultured on a potato dextrose agar (PDA) plate were white to pale yellow, two types of conidia: α-conidia (5.88x1.57 μm) were hyaline and oval to fusoid ; β-conidia (23.69x1.19 μm) were hyaline and filiform with characteristic curves, and was identified as Phomopsis sp.. SB isolate cultured on PDA plate were to produce abundant, cotton white to fluffy mycelia. Conidia (22.73×13.02 μm) were initially hyaline, aseptate and ellipsoid. Mature conidia are uniseptate and brown walled, and was identified as Botryosphaeria rhodina. FD isolate cultured on PDA plate were white cotton aerial mycelia. Conidia (18.78×5.86 μm) were spindle-shaped, and was identified as Neofusicoccum parvum. FS isolate cultured on PDA plate were white cotton aerial mycelia, but the mycelium length shorter than the FD isolate. Conidia (20.55×5.63 μm) were spindle-shaped, and was identified as Botryosphaeria dothidea. F4 isolate cultured on PDA plate were white flat mycelia. Conidia(30.97 μm) were one-cell and spherical, and was identified as Phytophthora palmivora. S3 isolate cultured on PDA plate were whitish yellow flat mycelia. Conidia (6.03×2.55 μm) were oval and one-cell, and was identified as Fusarium solani. Pathogenicity of six isolates were tested on Irwin mango fruits, except for Fusarium solani, others could cause fruit rot symptom on the fruits. Use of chemical reagents, 39.5% Fluazinam SC acted on FD, FS, SB, F6 isolates had below 0.01μg/ml 50% effective concentration (EC50), but acted on F4 was only below 10 μg/ml 50% effective concentration (EC50), and it was best chemical reagents for F4 isolate on this study. 62.5% Cyprodinil +Fludioxonil WG acted on FD isolate had below 0.01 μg/ml 50% effective concentration (EC50). 50% prochlorate manganese WP acted on F6 isolate had below 0.01 μg/ml 50% effective concentration (EC50). Use of biological reagents, Bacillus amyloliquefaciens BACY1 biofungicide had the best effect of confrontational inhibition on FD, FS, SB, F6 isolates, and B. amyloliquefaciens A1 acted on F4 isolate was better than others. The oppressed inhibition of all Biofungicides were good effect on FD, FS, SB, F6 isolates, except for F4 strains.

Current demands for the reduction of negative impact of activities influencing the environment directly concern the process of care and maintenance of golf areas. The conviction of the need to minimise the negative influence of technology on the golf course has led to the implementation of alternative techniques and preparations. The aim is to provide the needed quality of lawn mainly by means of organic substances in the most environmentally-friendly way. The primary principle thus is the exclusion of any chemical substances from the group of pesticides. The objective of the diploma thesis was the detection of the influence of chosen organic substances on the quality of the lawn. Besides the overall quality of the lawn, the influence of individual substances on partial features of the quality was evaluated such as the density of lawn, turf cover, colour of lawn, damage caused by diseases, occurrence of weeds and aesthetic appearance. The evaluation of the influence of the substances was carried out in Vrbinky golf course in Piešťany during full operation of areas as well as during maintenance (mowing, irrigation, fertilization, without the usage of pesticides). The aim of such way was the simulation of real care of the golf course. The choice of substances was influenced by the demand on the representation of different groups of substances. Biofungicide, extract from sea algae and mycorrhiza were used in the experiment as well as two substances of organic fertilizer. Experiment areas were founded on two different types of lawn: on the fairway and semi-rough. The evaluation of observed features and overall quality was being carried out during the whole period of observation. Interpretations dealt with the evaluation of data independently of terms. The evaluation of results of measurement on the areas of fairway did not show any fundamental influence of substances on the overall quality of the lawn in comparison with the area where no substance had been used. The evaluation of results of the influence on the overall quality on the area of semi-rough showed significant improvement of the quality of the lawn in the areas where bio-fungicide had been used in comparison with the area where no substance had been used.

碩士<br>國立中興大學<br>植物病理學系<br>89<br>By using Czapek’s broth as a basal medium, effect of various carbon and nitrogen sources on growth, sporulation and antibiotic production of Gliocladium virens SGV7 isolate were explored by a shaking flask culture system. Among 12 carbon sources tested, mannose was found the best to support the mycelial growth and conidial production. In mannose containing medium, the mycelial growth reached approximately 190 mg / 50 ml culture that was more than 4 times comparing to that in glucose containing medium. Likewise, the maximum conidia yield in mannose treatment reached approximately 5.7 X 107 /ml, whereas that of glucose treatment was only 5.1 X 106 /ml. A total of 16 nitrogen sources were screened, N-compound was among them the best for supporting the mycelial growth and as well for the chlamydospore production. In a 0.3 % N-compound amended treatment, the mycelial growth reached approximately 250 mg / 50 ml culture at 10 days after inoculation; and accompanied to that production of about 107 chlamydospore /ml was observed. The productivity of chlamydospore in this N-compound amended medium was further improved with the addition of yeast powder, oat meal and sucrose respectively. With the addition of 2 % yeast powder or 2 % oat meal, the yield of chlamydospore was increased further up to 2 X 108 / ml level. As regards to antibiotic production, addition of fructose, maltose and sucrose were of greatly stimulatory, but the increased provision of N-compound tended to reduce the activity. For the mass production of chlamydospore formulation by liquid culture system, a nature medium consisting 2-3 % (w/v) oat meal, 0.2-0.3 % (v/v) N-compound, 2% (w/v) sucrose and 2% (w/v) yeast powder is highly recommended. As an well-known antagonistic fungus existing all over the world, the potential of Gliocladium spp. in the control of soilborne diseases has been well recognized. Commercialization of this fungus as biofungicide has been successful in certain advanced countries; and the number of available commercial product is increasing. To explore the use of this fungal resource native in Taiwan, however, technique platform for the mass production is badly needed. In tradition, the fungus was produced by solid fermentation in which most of the efforts were aimed to the conidia production. The major pitfall for the conidia preparation was the limitation of poor shelf life. To cope with that, cultural system aiming for chlamydospore production has been successfully established and commercialized. The main objectives of this study were to improve the technique for the solid fermentation production of conidia and the liquid fermentation production of chlamydospores. Gliocladium virens SGV7 isolate was used as a model system for the technique platform establishment. For solid fermentation, a plastic vial system primarily used for mushroom production was adapted. Improved technology for water addition and moisture control optimization was successfully established. Direct addition of 55% (v/w) water prior to autoclaving of the oat grain medium was found appropriate to support the fungal growth and conidia production. Also found critical was the use of plastic film to provide a better moisture content during the early stage of mycelial growth. With an improved water content and moisture condition, the spore yield increased greatly. The best yield ( up to 3 X 109 conidia/g ) was observed in a system where mixture of wheat bran and fine sugarcane baggase ( 1:3, v/v ) was used to replace oat grain as a cultural substrate. The major advantage of using this substrate mixture was the loose texture and better water retaining capability. Upon harvest of the conidia preparation, formation of chlamydospores was generally observed on the residual culture substrate. As regards to the production of chlamydospores, the addition of N-compound was found greatly stimulatory, the amount of chlamydospore formation reached 107/ml in a traditional 50 L stirrer tank liquid fermentor. Moreover, the established technique platform was demonstrated working also for 2 other Gliocladium isolates and 1 Trichoderma isolate in regarding to chlamydospore production. As for the disease control efficacy, the chlamydospore preparations of G. virens SGV7 isolate and Trichoderma sp. YT-3 isolate were shown to be effective in reducing the infection of cabbage by R. solani AG4, and in improving the survival rate and growth vigor of the cabbage seedlings.

碩士<br>國立中興大學<br>植物病理學系所<br>98<br>The Bacillus subtilis group bacterium is renowned for its importance as natural resources for biofungicides, and many other agro-industry applications. The bacterium has attracted great attention recently for its use in producing poly-γ-glutamic acid (γ-PGA) which has multi-function and is now one of the most favored biotech products. In agriculture, the major application of γ-PGA which has attracted most attention includes improvement of soil structure and water holding capability, the supplementation of organic nitrogen, and the promotion of plant growth. The main objective of this investigation is to explore the production of γ-PGA by the antagonistic bacilli known with potential in biofungicide application, to optimize the production, and to learn its significance in regarding to the growth promotion and disease control effectiveness. The ultimate goal is to provide some useful data bases for strengthening the market value of targeted biological fungicide. Using HSP1, TKS1-1, TLB7-7, OF3-16, WG6-14, SP4-17, and natto2 antagonistic Bacillus subtilis group bacterium as test strains, production of γ-PGA was compared on monosodium glutamate (MSG) supplemented SYM and 523 medium, and on medium E wherein L-glutamate was substituted by MSG. Examination on γ-PGA production on these 3 media indicated that TLB7-7 was among the tested strains which gave the highest yield. By a two step culture system that the test strains were allowed to grow in SYM for 18 hrs before transferred to MSG substituted Medium E (abbreviated as SYM/E in the following), the γ-PGA yield of TLB7-7 reached approximately 12 mg/ml. And the results of SDS-PAGE also indicated the produced γ-PGA has molecular weight greater than 95kD. By drenching application, the effect of culture broth with and without γ-PGA production on water holding capability of soil in plastic pots were compared in greenhouse. At 10 days after treatment, the residual water content of soil treated with culture broth containing 6 mg/ml γ-PGA was 150% higher than that treated with only water. The effectiveness of γ-PGA in strengthening water holding capability of soil was clearly demonstrated. For greenhouse growing vegetable soybean and cabbage plants drenching treated with 100x diluted γ-PGA containing broth culture twice a week, significantly promoted plant growth were observed. The fresh weight of vegetable soybean roots was significantly increased 61% while that of cabbage was increased 46.2-80.6%, as compared to that of control plants treated with only water. As for disease control, the water and spray application of these γ-PGA containing culture broths were found to be effective in controlling cabbage damping off disease and leek rust disease (Puccinia allii (DC.) Rudolphi). For pot grown leek plants artificially inoculated with urediniospore suspension at 104 spore/ml, the simultaneous application of the γ-PGA containing broth culture of the bacilli strains nearly completely inhibited the infection of the urediniospores. The inhibitory effect of rust infection was still evident even the culture broth was applied 24 hours after urediniospores inoculation. The reduced rust infection was due evidently to the inhibition of spore germination and germ tube development. On a glass slide system, the application of the culture broth was found leading to greatly reduced germination, and the germ tube growth was greatly reduced and deformed. The inhibitory effect on spore germination appeared to be concentration dependent. Moreover, the effectiveness was found better by broth culture rather than filtrates obtained by Millipore membrane filtration indicating the involvement of secreted and spore-contained antibiotic in the antifungal function observed. In addition to broth culture system, the γ-PGA production of tested strains was also explored by solid state fermentation system. Among the 7 tested strains, WG6-14 and SP4-17 performed the best in the regard of γ-PGA productions and antagonistic effectiveness against Rhizoctonia solani AG4. Along with γ-PGA production, the 2 strains were also found to be the best in the production of volatile compounds which appeared to be effective in promoting plant growth. During the course of broth culture of SP4-17 and solid fermentation of SP4-17 and WG6-14, volatile compounds were collected from the air space of the culture container. By GC/MS, the production of 2,3-butanediol, the compound known to be of plant growth promoting effectiveness was identified. Although the correlation of the identified volatile compound and the observed plant growth promoting effect remain to be illustrated, the volatile compounds collected from WG6-14 and SP4-17 strains during the solid-state fermentation process were found to be inhibitory to the growth of Rhizoctonia solani AG4. The inhibitory effect observed was clearly dose dependent. What worth to mention is that at high dose application, the volatile compounds appeared to kill the tested fungus in 24 hours. The combined effect of γ-PGA and plant growth promoting / fungicidal metabolites shown in this study appeared to indicate a valuable way to the industrial formulation improvement of the targeted biofungicide.

碩士<br>國立中興大學<br>生命科學系所<br>100<br>This research aims at promoting the rate of pesticide degradation through biodegradation by applying fermentation on leaf surface and soil. This can in turn reduce the potential danger of using pesticides. Pesticides, including imidacloprid, fipronil, pyridaben, indoxacarb, chlorpyrifos, difenoconazole, azoxystrobin, and carbendazim were sprayed on Brassica campestris L. ssp in the initial experiment in the greenhouse. Fermentations produced by Bacillus subtilis strains TKS1-1, WG6-14, and SP4-17 Streptomyces sp.strain S3 were applied at an interval of one day. After collecting the aboveground parts of the plants, pesticides were extracted with QuChERS and then solved in acetonitrile. The solutions were submitted for LC/MS/MS analysis. In the initial experiment, pesticides, including azoxystrobin, difenoconazole, ipronil, and pyridaben and three bacteria strains TKS1-1, WG6-14 and S3 were selected for further research. Diluting four pesticides azoxystrobin、pyridaben、 fipronil and difenoconazole in different recommended concentration, and then coculture with distinct Bacillus subtilis strain TKS1-1、WG6-14 and Streptomyces sp. strain S3 in potato sucrose agar. There was no inhibition when TKS1-1、WG6-14 and S3 cocultured with four specific pesticides together.。TKS1-1、WG6-14 or S3 were grown in Tryptic Soy Broth.The cultures and were kept at 30℃under continuous shaking for 9 days. TKS1-1、WG6-14 and S3 grew normally and the degradation of four pesticides were visible. The interaction between azoxystrobin、pyridaben、 fipronil with S3 had the best promote degrade rate. Four leafs vegetables, Brassica campestris L. ssp, Brassica oleracea L. var. alboglabra Musil, Lactuca sativa L. and Ipomoea aquatica Forsk. are chosen as experiment materials in this research to test the interaction between pesticides and microorganisms on vegetables surface. The result showed the fastest degrade rate was TKS1-1、WG6-14 and S3 between azoxystrobin on Lactuca sativa L., on the 2nd day, and the second fast rate was degraded fipronil on the 4th day. Same as above, the fastest degrade rate was TKS1-1、WG6-14 and S3 between azoxystrobin and pyridaben on Ipomoea aquatica Forsk. on the 2nd day, especially S3 was the top. Also, the fastest degrade rate was azoxystrobin, the next was fipronil on Brassica oleracea L. var. alboglabra Musil. The best effect of degrade interaction was TKS1-1 then were WG6-14 and S3 on Brassica oleracea L. var. alboglabra Musil. Briefly conclude, the degrade rate from fastest to slowest was azoxystrobin, difenoconazole, pyridaben, fipronil on Brassica campestris L. ssp, and S3 was the best at promoting the degrade rate of azoxystrobin and difenoconazole. According of the result of leafs vegetable surface experiment fungicide azoxystrobin and pesticide fipronil and S3 are chosen to operate the follow-up experiment, also adding new pesticides included cyazofamid, amisulbrom, kresoxim methyl, trifloxystrobin and carbaryl and Streptomyces sp.strain S1. S1 and S3 could promote the degrade rate of azoxystrobin, rifloxystrobin and kresoxim methyl, but there was no obvious promote effect at amisulbrom and cyazofamid when they were cocultured in Tryptic Soy Broth. S1 and S3 could also promote the degrade rate of carbaryl and fipronil on the 6th day. After watering pesticides azoxystrobin, kresoxim methyl, trifloxystrobin, carbaryl and fipronil with fermentation S1 and S3, and observed the interaction between bacteria and the pesticide degrade rate. The result appear that S1 and S3 were not improve the degrade rate of pesticides in soil. After adding extra organic materials, 0.25 % wheat middlings and 0.25 % shrimp and crab shell powder, could maintain S1 and S3 bacteria activation in soil, and fermentation were promote the degrade rate of carbaryl, trifloxystrobin and fipronil slightly on the 3rd day. From all the above, we can conduct (1) Bacillus subtilis strains TKS 1-1, WG6-14 and Streptomyces sp.strain S1, S3 could promote the degrade rate of pesticide. (2) S1 and S3 were good at degrading fungicides strobilurins azoxystrobin, kresoxim methyl and trifloxystrobin. (3) The interaction effect between fermentation and pesticidesabout the degrade rate was much more obvious on leafs vegetable than on soil. The action mode and metabolite in the course of bacteria degrade pesticides will be a further target derived from this research in future works.

碩士<br>國立中興大學<br>植物病理學系<br>91<br>柒、英文摘要 The potential of Streptomyces fimbriatus WRS9 as a microbial biofungicide and the development of polymerase chain reaction primer for specific detection of Streptomyces spp. Chiung-ying Chiu In the discussed thesis works, the biological characteristics of Streptomyces fimbriatus WRS9 pertaining to its potential application as a biofungicide for plant disease control were evaluated using S. griseobrunneus WRS3, S. lincolnensis WRS7, and S. saraceticus SS31 as compared strains. In a preliminary screening test, WRS9-which was originally isolated from sugarcane rhizosphere, was found superior in strength of chitinolytic activity and antagonisity against Pyricularia oryzae, Pythium aphanidermatum and Phytophthora palmivora, than that of the three compared strains. In a broth culture system under continuous shaking, it produced at least 6 inducible chitinase isozymes with molecular weight ranging from 32 to 60 kDa, in responding to the presence of colloidal chitin or the mycelial suspension of Rhizoctonia solani AG4. The bacterium grows well in 2-3% oat broths, the biomass yield reached 3.19x108 cfu/ml 6 days after inoculation (DAI). As a comparison, the bacterial growth in 2% corn and 2% wheat bran broth were comparatively less well; the biomass yield reached only 2.03-1.99x107 cfu/ml at six DAI. In paralleled to the bacterial growth, the antagonisity against P. aphanidermatum was detected from all oat and corn broth cultures at 1 DAI which then hold throughout the 5th day after inoculation and declined to non-detectable at 6 DAI . In a wheat bran broth culture, however, the antagonisity remained non-detectable throughout the 6 days culture period except that a slight increase of antagonisity was detected at 5 DAI. A total of 7 natural agar media were screened for the performance for supporting the sporulation of the test bacterium. Among them, the 0.2 % maltextract amended potato sucrose agar (PSMe) appeared to be the best, the spore yield reached approximately 4.67x109 cfu/plate at 5 DAI. Other test media with good performance in supporting the sporulation of WRS3 include 2% wheat bran, PSA and chitin agar; the yield of biomass all achieved 2.78-3.36x109 cfu/plate level. When applied as inoculum for liquid culture using oat broth medium, spore samples obtained from all these natural agar media all performed equally well in regarding to the yield of biomass except that from 2% corn agar which tended to have a lower yield. A pilot scale mass production of test bacterium was attempted using 5 to 50 L stirrer type fermentor. By an established protocol developed for SS31 and as well for WRS3, the yield of biomass obtained all remained less than 108 cfu/ml. Although the fine tune of the protocol need to be worked out, the potential application of the broth cultures produced in disease control was attempted using papaya root rot (caused by Phytophthora palmivora) as trial target. In a 7-day old suspension culture of P. palmivora growing in PSB broth, the inoculation by WRS9 at 3x106 cfu/ml caused an increased leakage of electrolytes approximately 24 to 36 hours after inoculation; an antibiotic function on the membrane damage was clearly indicated. A followed examination by light microscopy further revealed that the pathogen mycelia were penetrated and/or tangled up by WRS9 mycelium, lost their cellular contents and were finally totally dismantled or even disintegrated. The mycoparasitic and structural damaging effect on pathogen mycelium seemed to implicate the functioning of lytic enzymes of WRS9. In a greenhouse trial, the drenching of 500 to 1000X diluted WRS9 cultural broth was shown slightly reduced the infection of papaya seedlings by artificially inoculated P. palmivora. The application of WRS9 cultural broth at 100X dilution however, greatly reduced the survival of the seedlings. A plausible reason for the observed deleterious effect on test seedlings appeared to due mainly the antibiotic toxicity on the root system. On papaya fruit artificially inoculated with P. palmivora zoospore suspension, the application of WRS9 at 105-106 cfu/ml in concentration one day before inoculation significantly deterred or even stopped the fruit infection. Another focus of this thesis work was the development of primer for specific detection and/or identification by polymerase chain reaction the members of Streptomyces spp. The major objective of the devoted efforts was to provide useful tool for monitoring the possible ecological impacts due to repeated application of viable propagules of the antagonistic Streptomyces strains attempted for disease control application. The genomic DNAs were extracted from a total of 9 Streptomyces strains namely WRS2, WRS3, WRS7, WRS9, WRS38, TYS15, TYS17 TYS19 and SS31. And from each of them, the 16S rDNAs were amplified by PCR using universal primer pair UNI16S-L and UNI16S-R and cloned by yT&A vector. All the cloned 16S rDNAs appeared to be approximately 1400 bps in size; the full sequence of that from WRS3, WRS7, WRS9 and SS31 were resolved. The sequence analysis by Pretty software (Seq-Web) using database from NCBI indicated that the cloned sequences from WRS7 had 95% identities comparing to that known for most Streptomyces. The comparative analysis of the 4 resolved sequences further indicated the existence of certain species-specific regions located at 171-181 respectively. And from these data information, WRS3-L, WRS7-L, WRS9-L and SS31-L each respectively as forward primer specific for the denoted strain were designed from 171-181 region; and likewise ScR-1 (679-691) and ScR-2 (951-968) were each designed to serve as the reverse primer. The followed extensive PCR amplification trial using WRS3-L, WRS7-L, WRS9-L each as specific forward primer, 16S-R, ScR-1, and ScR-2 each as reverse primer, and the genomic DNAs obtained from S. griseobrunneus WRS3, S. lincolnensis WRS7, S. fimbriatus WRS9, 5 other Streptomyces spp. including WRS2, WRS38, TYS15, TYS17, and TYS19, and 5 other non-Streptomyces bacteria including Bacillus sp., Pseudomonas sp., Erwinia sp., and Xanthomonas spp. 1 and 2, each respectively, as template DNA. The results obtained indicated the use of WRS3-L/ScR-2 as primer pair detected the predicted 797 bps fragment only from WRS3; that of WRS7-L/ScR-2 detected the 797 bps fragment only from WRS7; whereas that of WRS9-L/ScR-2 detected the 797 bps fragment only from WRS9. All the other tested forward/reverse primer pair combinations, as the contrary, were not successful in terms of specific detection of the attempted bacterial strain. For the specific PCR detection of WRS9, the spore suspension at serial dilution was tested for its efficacy in replacing the template function of genomic DNAs. The application of WRS9-L/UNI 16S-R as primer pair was successful in detecting the predicted 1266 bps fragment; the detection limit went down to about 108 cfu/ml diluted 10-4 level. For the detection/identification of specific Streptomyces species/strains, the detailed protocol of the detection may need further improvement for each specific target strain, the use of species specific 16S rDNA sequence as forward primer appeared to be a valuable tool.