Orientador: Marta Cristina Teixeira Duarte / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-27T13:08:18Z (GMT). No. of bitstreams: 1 Almeida_GustavoSteffende_M.pdf: 767493 bytes, checksum: c194394bcc80ba1852de47976dba16ad (MD5) Previous issue date: 2015 / Resumo: A cultura do morango é de grande importância no contexto agrícola mundial, com uma produção anual que supera 4,5 milhões de toneladas. Porém, as características desta fruta a tornam altamente susceptível a fatores físicos e biológicos de deterioração, tornando-a altamente perecível e acarretando altos níveis de perdas no campo e na pós-colheita. Dentre os fatores biológicos tem destaque a ação de fungos fitopatogênicos, dentre os quais o 'Botrytis cinerea' e o' Colletotrichum gloeosporioides' tem papel principal. Dentre as alternativas naturais para controle destes fitopatógenos, os óleos essenciais de plantas medicinais e aromáticas vêm sendo investigados. Neste contexto, no presente trabalho a atividade antifúngica de óleos essenciais de nove espécies de 'Citrus' e de 'Cymbopogon citratus' foi avaliada in vitro contra 'B. cinerea' e' C. gloeosporioides'. Os óleos de 'Citrus sinensis' e 'C. citratus' foram os mais ativos in vitro (MIC ¿ 0,25 e 0,06 mg.mL-1, respectivamente) e, portanto, selecionados para os ensaios com morangos in natura, visando manter sua qualidade pós-colheita. Os ensaios foram conduzidos sob duas condições ambientais, ou seja, sob condições ambiente de armazenamento (25 ºC) e em armazenamento refrigerado (10 ºC). Aplicados na concentração 1,0 mg.mL-1 , o óleo essencial de 'C. sinensis' mostrou-se mais eficaz sob condições ambiente de armazenamento, e a mistura dos dois óleos em partes iguais em armazenamento refrigerado. Em ambas as condições, melhores resultados foram obtidos através da aplicação por contato direto. Os óleos essenciais foram ainda incorporados a um filme de revestimento composto por matriz de metil-celulose e testados in vitro quanto ao seu potencial de inibição de 'B. cinerea'. Nestas condições, o óleo essencial de 'C. sinensis' mostrou-se o mais eficiente. Através dos resultados foi possível concluir que os óleos essenciais são uma opção viável para o controle de fitopatógenos em morango e para manutenção de sua qualidade pós-colheita / Abstract: The strawberry crop has great importance in agricultural world wide context, with an annual production exceeding 4.5 million tons. However, the characteristics of this fruit make it highly susceptible to physical and biological damage, making it easily perishable and causing losses in field and postharvest. Among the biological factors, the action of phytopathogenic fungi such as 'Botrytis cinerea' and "Colletotrichum gloeosporioides" have a main role. Natural alternatives have been proposed in order to replace synthetic products currently used in control of these plant pathogens, of which the essential oils from medicinal and aromatic plants have demonstrated good potential. In this context, the present study evaluated the in vitro antifungal activity of the essential oils from nine 'Citrus' species and from' Cymbopogon citratus' against 'B. cinerea' and 'C. gloeosporioides'. 'Citrus sinensi's and 'C. citratus' essential oils showed highest activities (MIC values 0.25 mg.mL-1 and 0.06 mg.mL-1, respectively) and were selected for the assays with in natura strawberries aiming at maintaining its postharvest quality. The tests were conducted under two simulated environmental conditions, ie, environment conditions of storage (25 ºC) and refrigerated storage (10 ºC). The crude essential oil of 'C. sinensis' (1.0 mg.mL-1) was the more effective in environmental conditions of storage, and the mixture of the two oils (1:1 ¿ 1.0 mg.mL-1) in refrigerated storage. In both conditions, best results were obtained when the oils were applied by direct contact. The essential oils were also incorporated into a coating film consisting of methyl cellulose matrix and tested to their 'in vitro' inhibitory potential against 'B. cinerea'. Accordingly, the essential oil of 'C. sinensis' proved to be the most effective as antifungal. The results allowed conclude that essential oils are a viable option for controlling phytopathogenic fungi in strawberry and for continuing postharvest quality / Mestrado / Ciência de Alimentos / Mestre em Ciência de Alimentos

京都大学 / 新制・課程博士 / 博士(農学) / 甲第23524号 / 農博第2471号 / 新制||農||1087(附属図書館) / 学位論文||R3||N5355(農学部図書室) / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 髙野 義孝, 教授 寺内 良平, 教授 吉田 健太郎 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

No description available.

Strawberries are considered an important crop in California where in 2018 it was in the top 5 valued fruit and vegetable commodities valued at $2.84 billion accounting for 88% of the total U.S. production. Strawberry production can be severely impacted by soilborne pathogens that can affect strawberry roots, crowns and leaves which can result in plant mortality. As much as 50 to 60% mortality can occur in one field. Pathogens responsible for such losses include Colletotrichum acutatum (syn.C. nymphaeae), Macrophomina phaseolina and Verticillium dahliae. With the phaseout of methyl bromide, host resistance and an understanding of host-pathogen interactions can play an important role in control of these diseases. A two-year study was conducted in order to evaluate host resistance of anthracnose in 105 cultivars and elite breeding lines developed by six strawberry breeding programs. Cultivars and elite breeding lines were inoculated using three local isolates in both years. All breeding programs provided genotypes that had a wide range of anthracnose susceptibility ranging from 0 to 100% mortality during both years. In both years an average of 78% of all the plant mortality occurred by 1 January. From the 105 cultivars and elite breeding lines, 30 cultivars were common to both years. Of these 30 cultivars, nine of them differed in their disease susceptibility between experiments by more than 20%. This suggests that several years of field evaluation may be necessary to determine susceptibility to anthracnose. Popular cultivars that represent the spectrum of susceptibility are Monterey (susceptible), Festival (moderately resistant), and Sensation (resistant). A second study was conducted toevaluate pathogen colonization of resistant and susceptible strawberry cultivars, testing interactions among crown and root plant tissue and two sampling timings. These cultivars were challenged with two soilborne pathogens, Macrophomina phaseolinaand Verticillium dahliae,over two years. Existing qPCR protocols for M. phaseolina and V. dahliae were used in order to quantify how much pathogen DNA was detected in crown and root samples. For the 2016-2017 V. dahliae trial there were significant effects for cultivar. Cultivar Benicia had significantly higher pathogen DNA compared to resistant cultivars Marquis, UC-12 and Camino Real. Susceptible cultivar BG 1975 had significantly less pathogen DNA compared to resistant cultivars San Andreas and Petaluma. In the 2017-2018 V. dahliaetrial pathogen DNA amount was not significantly different based on cultivar, plant part colonization, or the sampling period. In the 2017-2018 M. phaseolina trial all three of the fixed factors, cultivars, plant part colonization and sampling period were statistically significant. Cultivar ‘Sweet Ann’ had a significantly higher level of M. phaseolinaDNA in the early vs. the late sampling.

京都大学 / 新制・課程博士 / 博士(農学) / 甲第24674号 / 農博第2557号 / 新制||農||1099(附属図書館) / 学位論文||R5||N5455(農学部図書室) / 京都大学大学院農学研究科応用生物科学専攻 / (主査)教授 髙野 義孝, 教授 寺内 良平, 教授 吉田 健太郎 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Industry demand for local sources of grain for animal feed has increased sorghum production in the mid-Atlantic region of the U.S. Sorghum anthracnose (causal agent Colletotrichum sublineola) and the grain mold complex, which includes mycotoxin-producing Fusarium spp., limit the yield and quality of grain sorghum in humid climates worldwide. A majority of U.S. grain sorghum production is in arid regions, and management strategies have not been developed for the mid-Atlantic U.S. where warm, wet conditions favor disease. The specific objectives of this research were to: (1) determine the effectiveness of fungicides and their application timing for the management of sorghum foliar anthracnose, (2) compare five grain sorghum hybrids for their susceptibility to foliar anthracnose, grain mold and mycotoxin contamination under field conditions, (3) integrate host resistance and fungicide application to manage anthracnose and grain mold, and (4) identify Fusarium spp. associated with grain mold and mycotoxin contamination of sorghum in the mid-Atlantic U.S. For Objective 1, it was determined that a single application of pyraclostrobin-containing fungicide no later than flowering reduced anthrancose, protected yield and maximized farm income. Objective 2 focused on sorghum hybrid selection as a disease management tactic, and it was determined that hybrids with high yield potential and moderate disease resistance should be selected for mid-Atlantic sorghum production in order to maximize grain yield and quality while minimizing the need for fungicide inputs. Objective 3 focused on integrated management and demonstrated that under moderate disease pressure, a high-yielding susceptible hybrid required a single application of pyraclostrobin-based fungicide to minimize fungal diseases and maintain acceptable yields, whereas under high disease pressure it was necessary to integrate hybrid resistance and judicous applications of fungicides. The aim of Objective 4 was to characterize potential causal agents of mycotoxin contamination in mid-Atlantic sorghum, and thirteen phylogenetically distinct Fusarium species (F. lacertarum, F. graminearum. F. armeniacum, F. proliferatum, F. fujikuroi, F. verticillioides, F. thapsinum and several in Fusarium incarnatum-equiseti species complex) were found to be associated with grain mold and fumonisin and/or deoxynivalenol contamination of sorghum grain. This work has provided insights into the impacts of fungal diseases on grain sorghum yield and quality in the mid-Atlantic and has aided in development of best management practices for the region. / Doctor of Philosophy / Sorghum is grown in tropics, sub-tropics and semi-arid region worldwide for food, feed, forage and fuel. Sorghum acreage in the mid-Atlantic is increasing due the demand for locally grown grain by poultry and swine industries. During the growing season, warm and humid conditions are common in the southeastern and mid-Atlantic states favoring fungal diseases development that reduce the grain yield and quality. Anthracnose and grain mold, which includes toxic mycotoxin-producing Fusarium species, are the two major constraints in sorghum production in the region. However, management alternatives have not been developed. The main goal of this research was to develop management strategies to protect yield and maximize farm profitability by controlling anthracnose and grain mold of sorghum using chemicals and/or host resistance. The specific objectives were to: (1) determine the effectiveness of fungicides and their application timing for the management of sorghum foliar anthracnose, (2) compare grain sorghum hybrids for their susceptibility to foliar anthracnose, grain mold and mycotoxin contamination under field conditions, (3) assess the value of integrating host resistance and judicious use of fungicides to manage sorghum anthracnose and grain mold, and (4) identify Fusarium spp. associated with grain mold and mycotoxin contamination of sorghum in the mid-Atlantic U.S. Results from this research indicate that a single application of pyraclostrobin-containing fungicides no later than flowering reduces anthrancose, protects yield, and increases farm income. Sorghum hybrids varied in susceptibility to anthrancnose and grain mold, and planting a moderately resistant hybrid and applying a fungicide under high disease risk conditions provided the greatest return on investment. Both fumonisin and deoxynivalenol were frequently detected from sorghum grain, and mycotoxin contamination was associated with 13 different Fusarium species from three distinct species complexes. Based on the results of this work, best management practices for minimizing sorghum disease losses were developed for the mid-Atlantic region.

Colletotrichum acutatum and C. gloeosporioides are fungal plant pathogens that have a global distribution, extensive host range, and convoluted taxonomy. Both species can cause grape ripe rot and are considered endemic to Virginia US. In 2012, C. acutatum and C. gloeosporioides were reclassified into species complexes that consist of 31 and 22 accepted species, respectively. The objectives of this study were to: 1) survey Virginia vineyards for grape ripe rot, and morphologically and phylogenetically identify isolates to the species within the complexes, 2) conduct an in vitro fungicide assay to screen fifteen commercial fungicides and combinations of two fungicides for efficacy to control isolates from seven Colletotrichum species from Virginia vineyards, 3) sequence gene fragments from three subunits of the SDH enzyme in the fungicide-screened isolates to observe potential resistance mutations, 4) investigate the susceptibility of three grapevine tissues to Colletotrichum species, 5) observe potential infection structures before and after the application of fungicides, 6) evaluate the efficacy of commercial fungicide controls of grape ripe rot in the field, and determine the most advantageous timing of applications. In my studies, I identified six Colletotrichum species: C. aenigma, C. conoides, C. fioriniae, C. gloeosporioides, C. kahawae, and C. nymphaeae. I also found two additional groups; an isolate similar to C. limetticola and C. melonis and a group of isolates that are similar to C. alienum, C. fructicola, and C. nupharicola. I also identified captan, and mancozeb as two potential active ingredients for control of grape ripe rot isolates from Virginia via the in vitro fungicide assay. Additionally, I found that combinations of two active ingredients could increase the efficacy of benzovindiflupyr, copper, and polyoxin-D. C. fioriniae germination and production of melanized appressoria was documented on leaves. I observed appressorium formation with isolates of two C. fructicola-like genotypes and C. nymphaeae, as well as secondary conidiation with isolates of C. aenigma, C. fructicola-like genotype 3, and C. nymphaeae on blooms. And finally, benzovindiflupyr, cyprodinil + fludioxonil pre-mix, and potassium phosphite + tebuconazole were identified as candidates for chemical control for grape ripe rot in the field. / PHD / Colletotrichum acutatum and C. gloeosporioides are two fungal plant pathogens that are found on a wide range of crops around the globe. Both fungal species cause the disease grape ripe rot and have been found in Virginia (VA) USA since the late 1800s. Originally, grape ripe rot was considered a minor disease in VA; however, based on communications with local VA vineyard managers, grape ripe rot was found to cause up to 30% direct crop loss. Further indirect economic loss occurs during wine production due to the production of unpalatable, tobacco-like, off flavors from the infected grapes. Sensory studies found this wine flavor change occurred with as little as 3% of the total crushed grapes being infected. Grape ripe rot appears as a sunburn-like, tan injury on the surface of white-fruited grape berries. As the disease progresses, the dark injury expands across the surface of the berry and rings of salmon-colored spore masses form. On red-fruited grapes, the formation of spore masses is usually the first observable sign. Over time, the infected berries will shrivel down to a soft, pustule-covered raisin. Both C. acutatum and C. gloeosporioides cause the same grape ripe rot symptoms on fruit and overlap in fungal appearance. In addition, investigations of these pathogens using molecular techniques have revealed that each consists of a number of genetically distinct groups that are difficult to distinguish by appearance. Therefore, in 2012, C. acutatum and C. gloeosporioides were reclassified into 31 and 22 newly accepted species, respectively, using molecular techniques. The objectives of this study were to: 1) survey VA vineyards for grape ripe rot, and visually and molecularly identify isolates to the species within the new complexes, 2) conduct a laboratory fungicide assay to screen fifteen commercial fungicides and combinations of two fungicides for control of isolates from VA vineyards, 3) sequence gene fragments from three subunits of the SDH enzyme in the fungicide-screened isolates to observe potential resistance mutations, 4) investigate the susceptibility of three grapevine tissues to Colletotrichum species, 5) observe potential infection structures before and after the application of fungicides, 6) evaluate the efficacy of commercial fungicide controls of grape ripe rot in the field, and determine the most advantageous timing of applications. In my studies, I identified six Colletotrichum species: C. aenigma, C. conoides, C. fioriniae, C. gloeosporioides¸ C. kahawae, and C. nymphaeae. I also found two additional groups; an isolate similar to C. limetticola and C. melonis and a group of isolates that are similar to C. alienum, C. fructicola, and C. nupharicola. Our lab also identified four active ingredients as potential controls of grape ripe rot in the laboratory fungicide assay; captan, mancozeb, tetraconazole and thiophanate-methyl. Additionally, combinations of two compounds can increase the effectiveness of benzovindiflupyr, copper, and polyoxin-D. of C. fructicola-like isolates, and C. nymphaeae formed infection structures on blooms. of C. aenigma, C. fructicola-like genotype 3, and C. nymphaeae formed spores on blooms without producing symptoms. C. fioriniae spores germinated and produced infection structures on leaves without producing symptoms.

The mango (Mangifera indica L.) is an appealing subtropical fresh fruit with a pleasant flavor and taste, high nutritional value, beneficial medicinal properties and various processing options. However, as is the case with most subtropical fruit, it is a sensitive commodity, prone to losses postharvestly. The South African mango industry is highly dependent on a hot water and cold prochloraz dip treatment, to control postharvest anthracnose and soft brown rot on fruit destined for export. However, negatve public perceptions of synthetic fungicides and its use on fresh produce for disease control has been increasing in major export markets such as the European Union. This growing concern from a public point of view is forcing industry to consider more environmentally acceptable methods to maintain quality of mangoes during extended export periods. ‘Tommy Atkins’ and ‘Kent’ mangoes either uninoculated or artificially inoculated with Colletotrichum gloesporioiedes, Botryosphaeria parva or sterile agar, were used to evaluate softer, greener alternatives, in this study. Fruit were subjected to either a hot, Bacillus amyloliquefaciens (PPCB004) containing dip treatment for two minutes or a 24 hour 1-methylcyclopropene (1-MCP) gas treatment at 16 ºC or no treatment. Fruit were then stored at 10 ºC under either 5% O2 and 5% CO2 (CA-1) or 3% O2 and 8% CO2 (CA-2) controlled atmospheres (CA) for 18 days and allowed to ripen for five days at 25 ºC. Similarly, uninoculated or artificially inoculated fruit subjected to B. amyloliquefaciens, 1-MCP or a combination of the two treatments was stored at 10 ºC for 18 days under conventional storage. ‘Tommy Atkins’ fruit were packed into bags made from four different film types, untreated or after being subjected to a cold B. amyloliquefaciens dip treatment and stored for 23 days at 10 ºC. Overall, ‘Kent’ fruit were more susceptible to anthracnose and SBR after artificial inoculation. In vivo inoculated ‘Tommy Atkins’ fruit, storage under CA-1 gave the best control of soft brown rot whilst CA-2 storage gave the best control of anthracnose. For quality retention no definite conclusion could be made for both cultivars after CA storage or the combination of 1-MCP pre-treatment and CA storage. The combination of 1-MCP pre-treatment and B. amyloliquefaciens maintained the quality of ‘Kent’ mangoes under conventional storage the best. Anthracnose severity on both cultivars was reduced with 1-MCP treated fruit combined with the biocontrol pre-treatment. Modified atmosphere packaging in this study was found to be ineffective in maintaining quality of mangoes. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2011. / Microbiology and Plant Pathology / unrestricted

Plants respond to insect and pathogen attack by inducing and accumulating a large set of defense proteins. Colonization of sugarcane stalk by opportunistic fungi, such as Fusarium verticillioides and Colletotrichum falcatum, usually occurs after Diatraea saccharalis (Lepidoptera: Cambridae) caterpillars attack increasing the damage caused by the borer. Two homologous of BARWIN protein were identified in sugarcane, SUGARWIN1 and SUGARWIN2. Their gene expression is induced in response to wound and Diatraea saccharalis damage. However, the recombinant SUGARWIN protein does not affect insect development; but promotes significant morphological and physiological changes in Fusarium verticillioides and Colletotrichum falcatum, which lead to fungal cell death via apoptosis, indicating that SUGARWINs may work as a first layer of defense against the fungi infection. In this study, we deepen our understanding of the role of SUGARWINs in plant defense and the molecular mechanisms by which these proteins affect fungi by elucidating their molecular targets. Our results show that SUGARWINs play an important role in plant defense against opportunistic pathogens. We demonstrated that SUGARWINs are induced by C. falcatum, and the induction of SUGARWINs can vary among sugarcane varieties. The sugarcane variety exhibiting the highest level of SUGARWIN induction exhibited a considerable reduction in C. falcatum infection. Furthermore, SUGARWIN1 exhibited ribonuclease and chitinase activity, whereas SUGARWIN2 exhibited only chitinase activity. This variable enzymatic specificity seems to be the result of divergent amino acid composition within the substrate-binding site. Additionally, plants attacked by insects and pathogens display profound physiological, morphological and chemical changes or adaptations, which may result in organism attraction or avoidance. In this study, we also aimed to understand the insect-fungi association in sugarcane and the role of fungal volatile compounds in this association. Our results have shown that D. saccharalis positively influences C. falcatum infection on sugarcane, inducing a fast growing when compared to C. falcatum treatment without D. saccharalis attack. In addition, both fungi, C. falcatum and F. verticillioides, have been shown a double effect on D. saccharalis caterpillar, they promoted a strong attraction for insects due volatile organic compound emission and positively influenced D. saccharalis feeding and weight gain in diets supplemented with fungi. Fungal volatile organic compounds from C. falcatum and F. verticillioides were identified and quantified; acoradiene and acorenol were specifically induced by the fungi. These data suggest a synergistic interaction, mediated by organic volatile compounds, between D. saccharalis and the fungi C. falcatum and F. verticillioides in sugarcane. / As plantas respondem ao ataque de insetos e patógenos induzindo e acumulando um grande conjunto de proteínas de defesa. A colonização do caule de cana por fungos oportunistas, como Fusarium verticillioides e Colletotrichum falcatum, geralmente ocorre após o ataque de lagartas de Diatraea saccharalis (Lepidoptera: Cambridae), resultando no aumento do dano causado pelo inseto. Dois homólogos da proteína BARWIN foram identificados em cana-de-açúcar, SUGARWIN1 e SUGARWIN2. A expressão desses genes é induzida em resposta ao ferimento mecânico e ao ataque de Diatraea saccharalis, entretanto, a proteína não afeta o desenvolvimento do inseto, mas promove alterações morfológicas e fisiológicas significativas em Fusarium verticillioides e Colletotrichum falcatum, causando a morte destes fungos por apoptose. Esses dados indicam que as SUGARWINs podem funcionar como uma defesa inicial contra a infecção fúngica. Neste estudo, aprofundamos nosso entendimento do papel das SUGARWINs na defesa de plantas e os mecanismos moleculares pelos quais essas proteínas afetam os fungos, elucidando seus alvos moleculares. Nossos resultados mostraram que as SUGARWINs desempenham um papel importante na defesa da planta contra patógenos oportunistas. Foi demonstrado que essas proteínas também são induzidas por C. falcatum em cana-de-açúcar, e sua indução pode variar entre as variedades de cana-de-açúcar. A variedade de cana-de-açúcar que apresentou o maior nível de indução de SUGARWINs apresentou uma redução considerável na infecção por C. falcatum. Além disso, SUGARWIN1 exibiu atividade de ribonuclease e quitinase, enquanto que SUGARWIN2 exibiu apenas atividade de quitinase. Esta especificidade enzimática parece ser o resultado da composição divergente de aminoácidos no sítio de ligação do substrato. Além disso, as plantas atacadas por insetos e patógenos exibem profundas alterações fisiológicas, morfológicas e químicas ou adaptações, que podem resultar em atração ou repelência do organismo, dessa forma, estudamos também a associação inseto-fungos na cana-de-açúcar, e o papel dos compostos voláteis fúngicos nessa associação. Nossos resultados mostraram que D. saccharalis influencia positivamente a infecção por C. falcatum em cana-de-açúcar, induzindo crescimento rápido do fungo quando comparado ao tratamento com C. falcatum sem ataque de D. saccharalis. Além disso, ambos os fungos, C. falcatum e F. verticillioides, mostraram um efeito duplo sobre lagartas de D. saccharalis, promovendo uma forte atração desses insetos devido à emissão de compostos orgânicos voláteis e influenciando positivamente a alimentação de D. saccharalis e ganho de peso em dietas suplementadas com fungos. Os compostos orgânicos voláteis fúngicos de C. falcatum e F. verticillioides foram identificados e quantificados; acoradieno e acorenol foram especificamente induzidos pelos fungos. Estes dados sugerem uma interação sinergistica, mediada por compostos orgânicos voláteis, entre D. saccharalis e os fungos C. falcatum e F. verticillioides em cana-de-açúcar.

Die pilzlichen Erreger der Tomate Alternaria solani und des Manioks Colletotrichum gloeosporioides f.sp. manihotis verursachen große Ertragsausfälle in Westafrika. In der vorliegenden Arbeit wurden die Blattkrankheiten nach Applikationen mit wässerigen Extrakten aus Westafrika (Ausgangsmaterial: organischer Haushaltsmüll) unter kontrollierten Bedingungen unterdrückt. Im Pathosystem Tomate - A. solani erzielten die Extrakte eine Befallsverminderung um bis zu 94 % im Vergleich zur Kontrollvariante und im Maniok - C. gloeosporioides wurde die Anzahl der gebildeten Acervuli/cm² Blattoberfläche bis um 87 % reduziert. Der primäre Wirkmechanismus der Extrakte gegen die Pathogene ist Antagonismus, hervorgerufen von den Mikroorganismen in den Extrakten. Isolierte Bakterien aus den Extrakten hemmten das Wachstum der Pathogene in Plattentests, was auf die Bildung von fungistatischen Substanzen zurückzuführen war. Die Bakterien, die aus den Extrakten isoliert und identifiziert wurden, gehörten überwiegend zu den Bakteriengattungen Pseudomonas und Bacillus. Die Extraktionsbedingungen nahmen in Hinblick auf die Wirksamkeit der Extrakte gegen die Pathogene eine wichtige Stellung ein. Die Untersuchungen zeigten einen Zusammenhang zwischen gestiegener Mikroorganismenanzahl und Befallsreduktion. Durch die Auswahl optimaler Extraktionsbedingungen erhöhte sich die Anzahl der Koloniedichte in den Extrakten; dies führte zur einer stärkeren Befallsreduzierung an der Tomate und am Maniok. Hierbei waren die Umgebungstemperatur und die Häufigkeit des Durchmischens des Kompost-Wasser-Gemisches von besonderer Bedeutung. Extrakte, die während der Extraktionszeit einer Temperatur von 20°C ausgesetzt waren, erzielten eine stärkere Befallsreduzierung von A. solani an der Tomate und wiesen eine höhere Mikroorganismendichte auf als Extrakte, die einer Temperatur von 30°C und 35°C ausgesetzt waren. Tägliches Durchmischen des Wasser-Kompost-Gemisches während der Extraktionszeit erhöhte die Mikroorganismendichte um das Siebenfache in den Extrakten und die Wirksamkeit gegen A. solani und C. gloeosporioides im Vergleich zu den Extrakten, die nur zu Beginn durchmischt wurden. Die Lagerungszeit der fertigen Komposte hatte einen Einfluß auf die Mikroorganismendichte der wässerigen Extrakte sowie auf deren Wirksamkeit. Extrakte, die aus frischen Komposten hergestellt wurden, zeigten einen besseren suppressiven Effekt gegen die Pathogene und wiesen eine höhere Mikroorganismenanzahl auf als Extrakte, deren Komposte schon länger gelagert worden waren. Die Anreicherung der Extrakte mit dem Formulierungshilfsstoff Xanthan steigerte die Wirksamkeit der Extrakte gegen A. solani an Tomatenpflanzen und gegen C. gloeosporioides f.sp. manihotis an abgetrennten Maniokblättern. Angereicherte Extrakte reduzierten den Befall um bis zu 46 % mehr als der Extrakt ohne Formulierungshilfsstoffe, während die Steigerung der Wirksamkeit nach Anreicherung mit Alginat oder Zellulose eine Abhängigkeit von der Herkunft der Komposte zeigte. Eine erhöhte ß-1,3-Glucanase-Aktivität wurde am vierten Tag nach der Applikation von Extrakten an der Tomate und an der Batate festgestellt. Diese Ergebnisse belegen die Bedeutung von Spritzbehandlungen mit wässerigen Kompostextrakten gegen die Pathogene A. solani und C. gloeosporioides f.sp. manihotis und stellen eine erfolgversprechende Alternative zur Bekämpfung von Pilzkrankheiten in Westafrika dar. / Great yield losses of cassava in West Africa are caused by fungal pathogens that also affect tomato, e.g. Alternaria solani and Colletotrichum gloeosporioides f sp. manihotis. In the present study these foliar diseases were effectively suppressed under controlled conditions after application of watery compost extracts to tomato and cassava The disease incidence of A. solani on tomato was reduced up to 94 % and the number of the acervuli produced on the surface of cassava leaves was reduced up to 87% compared to the control treatment. Reduction is due to antagonistic effects of the microorganisms in the extracts towards the pathogens. Bacterial strains isolated from the extracts suppressed the growth of the pathogens in dual-culture-tests due to the production of antibiotics. Bacteria isolated and identified from the extracts were mostly pseudomonas and bacillus strains. The conditions used for extraction of compost played a significant role for their effectiveness against different pathogens. The investigations showed that optimisation of extract conditions increased the density of microorganisms in the extracts and led to a higher disease reduction on tomato and cassava plants. Temperature and stirring frequency of the compost - water mixture during the extraction period were very important factors for increased effectiveness. Extracts incubated at 20 °C during the extraction period caused a higher disease reduction on tomato and showed a higher density of microorganisms, than extracts that were incubated at 30 or 35 °C. Daily stirring of the compost - water mixture during the extraction period increased the density of microorganisms in the extracts sevenfold and increased the effectiveness against A. solani and C. gloeosporioides compared to the extract that was stirred only once at the beginning. The Effectiveness as well as the density of the microorganisms were depended on the incubation time of the compost extracts. Extracts produced from fresh composts showed greater suppressive effects against pathogens and higher densities of microorganisms than extracts of composts that were stored for a longer time. Enrichment of the extracts with the formulate substance xanthan increased the effectiveness against A. solani on tomato plants and against C. gloeosporioides on detached leaves of cassava and reduced the disease incidence up to 46% compared to the extract without formulate substances. The increase of the effectiveness after enriching with alginate was depended on the origin of the compost. An increased ß-1,3- glucanase activity were determined on tomato and sweet potato leaves 4 days after the application of the extracts onto the plants. The results of this study show that watery compost extracts can be successfully applied against the cassava and tomato pathogens A. solani and C. gloeosporioides f. sp. manihotis and offers easily applicable methods for the reduction of fungal diseases in West Africa.