Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2012. / Submitted by Elna Araújo (elna@bce.unb.br) on 2012-09-14T00:53:09Z No. of bitstreams: 1 2012_KleniaRodriguesPacheco.pdf: 2182418 bytes, checksum: 30aa13c050c27588ce64e0710d842f13 (MD5) / Approved for entry into archive by Leandro Silva Borges(leandroborges@bce.unb.br) on 2012-09-14T20:00:04Z (GMT) No. of bitstreams: 1 2012_KleniaRodriguesPacheco.pdf: 2182418 bytes, checksum: 30aa13c050c27588ce64e0710d842f13 (MD5) / Made available in DSpace on 2012-09-14T20:00:04Z (GMT). No. of bitstreams: 1 2012_KleniaRodriguesPacheco.pdf: 2182418 bytes, checksum: 30aa13c050c27588ce64e0710d842f13 (MD5) / O feijoeiro (Phaseolus vulgaris) é suscetível a muitas doenças, entre elas, se encontra a murcha-de-esclerócio (podridão do colo) causada por Sclerotium rolfsii. O controle do S. rolfsii ocorre com o auxílio de práticas preventivas e por controle biológico ou químico. O estudo teve como objetivo selecionar e testar isolados de Trichoderma oriundos de solos do DF, avaliar e comparar os Trichoderma spp. selecionados e fosfitos (Cu, Ca, Mg e K) aos fungicidas no controle da murcha-de-esclerócio. Nos ensaios realizados foram utilizados dois isolados de S. rolfsii (UB 193 e UB 228). Dos 65 isolados de Trichoderma testados in vitro selecionaram-se os seguintes: 5, 11, 12, 15, 102, 103, 127, 136, 137, 1525, 1637, 1642, 1643, 1649, 1700 e EST 5. Esses isolados de Trichoderma, bem como os fosfitos [Fosfito: Cu (25% P2O5 + 5% Cu); K1 (40% P2O5 + 20% K2O); Mg1 (30% P2O5 + 4% Mg); Ca1 (30% P2O5 + 7% Ca); Ca2 (10% P2O5 + 6% Ca); K2 (40% P2O5 + 20% K2O); K3 (20% P2O5 + 20% K2O); K4 (30% P2O5 + 20% K2O); K5 (27% P2O5 + 27% K2O)] e fungicidas [Tebuconazol (250 g/L); Tiofanato-Metílico (500 g/L); Procimidona (500 g/kg); Carbendazim (500 g/kg)] foram avaliados quanto ao efeito sobre a germinação de esclerócios do patógeno em laboratório e sobre a doença em casa de vegetação. Os isolados de Trichoderma 1649, 1525 e 1637 foram os mais eficientes na inibição da germinação de esclerócios de S. rolfsii em laboratório. Além disso, os isolados 5, 12, 102, 103, 1525 e 1649 foram eficientes na melhoria do número de plantas sadias de feijoeiro em casa de vegetação. Dos testes realizados com fosfitos, as formulações com Potássio (K2) e Cálcio (Ca1) controlaram o patógeno no teste em casa de vegetação. Dos agentes químicos testados, o produto que reduziu significativamente a doença foi o Tebuconazol. _________________________________________________________________________________ ABSTRACT / Phaseolus vulgaris (Common bean) is susceptible to several diseases, among them there is the sclerotium wilt, also known as stem rot caused by Sclerotium rolfsii. The control of the disease could be throughout preventive practices or by biological or chemical control. This study was carried out to evaluate the effects of Trichoderma spp., phosphites (Cu, Ca, Mg, and K) and traditional fungicides to control sclerotium wilt of common bean. The experiments were performed with two isolates of S. rolfsii (UB 193 and UB 228). Sixty-five Trichoderma isolates were tested in vitro for inhibition of S. rolfsii, and the following ones were selected: 5, 11, 12, 15, 102, 103, 127, 136, 137, 1525, 1637, 1642, 1643, 1649, 1700 and EST 5. These selected Trichoderma, phosphites [Phosphite: Cu (25% P2O5 + 5% Cu); K1 (40% P2O5 + 20% K2O); Mg1 (30% P2O5 + 4% Mg); Ca1 (30% P2O5 + 7% Ca); Ca2 (10% P2O5 + 6% Ca); K2 (40% P2O5 + 20% K2O); K3 (20% P2O5 + 20% K2O); K4 (30% P2O5 + 20% K2O); K5 (27% P2O5 + 27% K2O)] and fungicides [Tebuconazole (250 g/L); Methyl Thiophanate (500 g/L); Procymidone (500 g/kg); Carbendazim ( 500 g/kg)] were tested for evaluation of sclerotial germination under laboratory conditions, and to evaluate the effects on disease of bean plants under greenhouse conditions. The Trichoderma isolates 1649, 1525 and 1637 were more efficient in reducing sclerotial germination. In addition, the isolates 5, 12, 102, 103, 1525 e 1649 significantly improved the number of non-diseased plants under greenhouse conditions. Phosphites of K (K2) and Ca (Ca1) inhibited sclerotial germination in laboratory and reduced disease in plants grown in greenhouse. Tebuconazole was the product that significantly reduced disease severity on bean under greenhouse condition.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A murcha-de-esclerócio causada por Sclerotium rolfssi é uma das mais importantes doenças do tomateiro em regiões tropicais. O presente trabalho foi realizado com o objetivo de selecionar rizobactérias que promovem o controle da murcha-de-esclerócio sem afetar o crescimento das plantas de tomateiro e verificar se o mecanismo de antiobiose e a inibição da difusão do ácido oxálico têm relação com a capacidade de controle. / The southern blight caused by Sclerotium rolfsii is one of the most important diseases of tomato in tropical countries. The aim of this work was select rhizobacteria capable to control the southern blight with no effect on tomato growth and investigative the correlation of antibiosis mechanism and inhibition of oxalic acid diffusion with the control of disease

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-20T11:47:13Z No. of bitstreams: 1 Leonardo Tavares de Souza.pdf: 1990421 bytes, checksum: 18cb117ba50c4733f5f4993b3f387024 (MD5) / Made available in DSpace on 2017-03-20T11:47:13Z (GMT). No. of bitstreams: 1 Leonardo Tavares de Souza.pdf: 1990421 bytes, checksum: 18cb117ba50c4733f5f4993b3f387024 (MD5) Previous issue date: 2013-02-15 / The southern blight, caused by Sclerotium rolfsii soilborne fungi, is an important disease in the culture of cowpea (Vigna unguiculata). The present work aimed: a) select, identify and verify the stability of antagonistic yeast isolates to S. rolfsii for biological control potential of rot southern blight in cowpea; b) elucidate the possible antagonistic activity in vitro of the yeast S. rolfsii, and the ability of yeast for growth promotion of cowpea plants. The experiments were conducted under conditions of a green house and in vitro assays. A total of five isolates, among 74 evaluated yeasts were selected in order to reduce the severity of southern blight in cowpea plants caused by an isolate of S. rolfsii pre selected in pathogenicity tests. Experimental tests showed that four out of five selected strains of yeast were stable in reducing disease severity in plants against three different isolates of S. rolfsii. There was a significant decrease in disease control was reduced when the concentration of these isolates yeast suspensions for seed treatment. The five selected yeast isolates were submitted to classification by classical taxonomy, considering the morphological, physiological and biochemical, as well as identifying the level of molecular biology, through sequencing of genomic regions ITS1 and ITS4. The five selected yeast isolates were identified as belonging to species Kodamaea ohmeri. In assays in vitro, all five strains of K. ohmeri showed activity "killer" positive, and observed an inhibition of mycelial growth of isolates of S. rolfsi grown on culture medium containing filtered extracted from strains of K. ohmeri for the majority of interactions tested. In tests of colonies pairings, only one isolate of K. ohmeri was effective in inhibiting the mycelial growth of two isolates of S. rolfsii between three pathogen strains evaluated. The tests of promoting plant growth, all five isolates K. ohmeri selected have generated significant gains in Shoot biomass of plants from seed treatment. The use of isolated K. ohmeri selected been shown as a promising tool for biological control to be incremented in the management of diseases caused by S. rolfsii in cowpea culture / A podridão-de-esclerócio, causada pelo fungo habitante do solo Sclerotium rolfsii, é uma importante doença na cultura do feijão caupi (Vigna unguiculata). O presente trabalho teve como objetivos: a) selecionar, identificar e verificar a estabilidade antagônica de isolados de leveduras a S. rolfsii no potencial de controle biológico da podridão-de-esclerócio em feijão caupi; b) elucidar as possíveis atividades antagônicas in vitro de leveduras sobre S. rolfsii, bem como a capacidade destas leveduras na promoção de crescimento de plantas de feijão caupi. Os experimentos foram conduzidos em condições de casa-de-vegetação e em ensaios in vitro. Um total de cinco isolados, dentre 74 leveduras avaliadas, foram selecionados visando a redução da severidade da podridão-de-esclerócio em plantas de feijão caupi ocasionada por um isolado de S. rolfsii pré-selecionado em testes de patogenicidade. Ensaios experimentais demonstraram que quatro dos cinco isolados de leveduras selecionados foram estáveis na redução da severidade da doença em plantas perante três diferentes isolados de S. rolfsii. Ocorreu uma significativa diminuição do controle da doença quando foi reduzida a concentração de suspensões destes isolados leveduras no tratamento de sementes. Os cinco isolados de leveduras selecionados foram submetidas à classificação por taxonomia clássica, considerando os caracteres morfológicos, fisiológicos e bioquímicos, bem como por identificação à nível de biologia molecular, através do sequenciamento das regiões genômicas ITS1 e ITS4. Os cinco isolados de leveduras selecionados foram identificados como pertencentes à espécie Kodamaea ohmeri. Em ensaios in vitro, todos os cinco isolados de K. ohmeri apresentaram atividade “killer” positiva, sendo observada uma inibição do crescimento micelial de isolados de S. rolfsi crescidos sobre meio de cultivo contendo filtrados extraídos dos isolados de K. ohmeri para a maioria das interações testadas. Em testes de pareamentos de colônias, somente um isolado de K. ohmeri foi eficiente na inibição do crescimento micelial de dois isolados de S. rolfsii entre três isolados do patógeno avaliado. Nos testes de promoção de crescimento de plantas, todos os cinco isolados de K. ohmeri selecionados geraram ganhos significativos na biomassa de parte aérea de plantas a partir do tratamento de sementes. O uso de isolados K. ohmeri selecionados, se demonstrou como uma ferramenta promissora de controle biológico a ser incrementada no manejo de doenças causadas por S. rolfsii na cultura caupi.

Submitted by Gizele Lima (gizele.lima@inpa.gov.br) on 2018-02-28T13:39:44Z No. of bitstreams: 2 Dissertação - Laysa Laborda.pdf: 1672119 bytes, checksum: a5ad9008dca40f70d1eafafec4e93ca3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-02-28T13:39:44Z (GMT). No. of bitstreams: 2 Dissertação - Laysa Laborda.pdf: 1672119 bytes, checksum: a5ad9008dca40f70d1eafafec4e93ca3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-12-14 / Fundação de Amparo à Pesquisa do Estado do Amazonas - FAPEAM / Cubiu (Solanum sessiliflorum Dunal) cultivation in the Amazonas state is limited by the high incidence of southern blight caused by the soilborne fungus Sclerotium rolfsii Sacc. The incorporation of plant material into the substrate changes the microflora present by increasing the organic matter content and by the plants decomposition exudates, which may be toxic or beneficial to the different microorganisms present on the substrate. The incorporated organic matter also increases the nutrient content available to the plant. The objective of this study was to evaluate the potential for control of southern blight by the incorporation of fresh comminuted biomass of four Fabaceae species: Erythrina fusca and Senna reticulata, native to Amazonia, and Desmodium heterocarpon and Gliricidia sepium, exotic to the substrate. The isolate of S. rolfsii was obtained from cubiu plants with disease symptoms and multiplied in autoclaved rice. Infestation of the substrate (argisol: chicken manure, 2: 1) was done with the incorporation of 10 g of colonized rice.L-1, in pots filled with 8 L of substrate, kept in a nursery. After 20 days of infestation, were incorporated 40 g of the Fabaceae biomass.L-1 substrate. The cubiu seedlings, 90 days after sowing, were transplanted one week after the incorporation of the Fabaceae. The experimental design was completely randomized, with three replicates and seven treatments: four species of Fabaceae and three controls, without the incorporation of biomass. In one control the substrate was not infested and in other, the plants were sprayed (9 mL.plant-1) twice, 50 days apart, with fungicide (Viper 700®, methyl thiophanate, 0.49 g a.i. for litter of water). Another experiment was carried out to evaluate the effect of doses of G. sepium incorporated into the substrate. The experiment had a completely randomized design and three replicates, with six treatments: incorporation of 40, 80, 120 and 160 g of G. sepium.L-1 substrate and two controls without incorporation of G. sepium. In one control, the plants were treated with fungicide. In this experiment, the pots were filled with 6 L of substrate infested as described in the previous experiment. In both experiments the disease and the inoculum incidence in the substrate were evaluated. In the first experiment, the data from the area below the disease progress curve were submitted to ANOVA and the means, compared by the Tukey test. In the second experiment, the data were submitted to regression analysis. In the first experiment the cubiu plants cultived in substrate with Fabaceae incorporation or treated with fungicide had the same southern blight incidence and in the pathogen suppression. In the second experiment, the incidence of southern blight was proportional to the G. sepium dose incorporated. With the incorporation of 139 g of G. sepium.L-1 no diseased plants were observed. Also the incorporation of 142 g G. sepium.L-1 substrate reduced the population of S. rolfsii in the substrate by 20%. / O cultivo do cubiu (Solanum sessiliflorum Dunal), no Amazonas, é limitado pela alta incidência da doença podridão-de-escleródio causada por Sclerotium rolfsii Sacc. A incorporação de material vegetal ao substrato de cultivo altera a microflora presente nesse substrato, tanto pelo aumento do teor de matéria orgânica, quanto pela liberação de substâncias, durante a decomposição desse material vegetal, que podem ser tóxicas, ou benéficas, a diferentes microrganismos presentes no substrato. A matéria orgânica incorporada aumenta, também, o teor de nutrientes disponíveis para a planta. O trabalho objetivou avaliar o potencial de controle da podridão-de-escleródio em cubiu por meio de incorporação, ao substrato de cultivo, de biomassa fresca triturada de quatro espécies de fabáceas: Erythrina fusca e Senna reticulata, nativas da Amazônia, e Desmodium heterocarpon e Gliricidia sepium, exóticas. O isolado de S rolfsii foi obtido de plantas de cubiu com sintomas da doença e multiplicado em arroz autoclavado. A infestação do substrato (argissolo: esterco de galinha, 2:1 ) foi feita com a incorporação de 10 g de arroz colonizado.L- 1 de substrato, em vasos preenchidos com 8 L de substrato, mantidos em viveiro. Após 20 dias da infestação, foram incorporadas 40 g da biomassa das fabáceas.L-1 de substrato. As mudas de cubiu, aos 90 dias da semeadura, foram transplantadas para os vasos uma semana depois da incorporação das fabáceas. O delineamento experimental foi inteiramente casualizado, com três repetições e sete tratamentos: quatro espécies de fabáceas e três testemunhas, sem a incorporação de biomassa. Em uma das testemunhas não houve infestação do substrato e em duas, o substrato foi infestado, sendo que em uma, as plantas foram pulverizadas (9 mL.planta-1) duas vezes, com intervalo de 50 dias, com fungicida (Viper 700®, tiofanato metílico, 0,49 g do i.a.L-1 de água). Outro experimento foi realizado avaliando-se o efeito de doses de G. sepium incorporadas ao substrato. O experimento teve delineamento inteiramente casualizado e três repetições, com seis tratamentos: incorporação de 40, 80, 120 e 160 g de G. sepium.L-1 de substrato e duas testemunhas sem incorporação de G. sepium sendo que em uma, as plantas foram tratadas com fungicida. Neste, os vasos tiveram 6 L de substrato infestado com a mesma dosagem de inóculo do experimento anterior. Em ambos os experimentos foi avaliada a incidência da doença e a densidade do inóculo no substrato. No primeiro experimento, os dados da área abaixo da curva de progresso da doença foram submetidos à ANOVA e as médias, comparadas pelo teste Tukey. No segundo experimento os dados foram submetidos à análise de regressão. No primeiro experimento as fabáceas não diferiram do fungicida na redução da incidência da podridão-de-escleródio e na supressão do patógeno. No segundo experimento, a redução da incidência da podridão-de-escleródio foi proporcional ao aumento da dose de G. sepium, apresentando 100% de controle com a incorporação de 139 g de G. sepium.L-1 de substrato. A dose de 142 g reduziu a população de S. rolfsii no substrato em 20%.

Allium white rot (AWR) is a soilborne disease that seriously damages commercial cultivation of onion (Allium cepa) and garlic (Allium sativum) crops. The disease has been found everywhere onions are cultivated and at present no system of control has been found that fully prevents the occurrence of the disease. The fungus responsible for the disease, Sclerotium cepivorum, uses oxalic acid to kill Allium bulb and root tissue in growing onion and garlic plants. Research suggests recombinant oxalate oxidase and oxalate decarboxylase enzymes may be able to degrade this acid and confer resistance against pathogens that rely on it, such as Sm. cepivorum or Sclerotinia sclerotiorum. To test the efficacy of these enzymes against white rot pathogens, three transgenes for wheat oxalate oxidase, barley oxalate oxidase and Flammulina oxalate decarboxylase were transformed into onions and garlic by Agrobacterium-mediated transformation. Allium species are highly recalcitrant to transformation, so these three transgenes were also transformed into tobacco to provide fast-recovering, easy to test transformants to assess the efficacy of the transgenes. Transformed garlic and tobacco lines were analysed to assess the integration and expression of the transgenes, then challenged with Sm. cepivorum or Sa. sclerotiorum, respectively, to assess the bioactivity of recombinant wheat oxalate oxidase, barley oxalate oxidase, and Flammulina oxalate decarboxylase against oxalic acid-dependent pathogens. Results show that one line of tobacco expressing the Flammulina oxalate decarboxylase enzyme was found to be consistently resistant to Sclerotinia sclerotiorum. Garlic lines transformed with this transgene failed to display stable transgene expression or disease resistance, possibly due to silencing of the transgene in recovered transformant tissue.

Allium white rot (AWR) is a soilborne disease that seriously damages commercial cultivation of onion (Allium cepa) and garlic (Allium sativum) crops. The disease has been found everywhere onions are cultivated and at present no system of control has been found that fully prevents the occurrence of the disease. The fungus responsible for the disease, Sclerotium cepivorum, uses oxalic acid to kill Allium bulb and root tissue in growing onion and garlic plants. Research suggests recombinant oxalate oxidase and oxalate decarboxylase enzymes may be able to degrade this acid and confer resistance against pathogens that rely on it, such as Sm. cepivorum or Sclerotinia sclerotiorum. To test the efficacy of these enzymes against white rot pathogens, three transgenes for wheat oxalate oxidase, barley oxalate oxidase and Flammulina oxalate decarboxylase were transformed into onions and garlic by Agrobacterium-mediated transformation. Allium species are highly recalcitrant to transformation, so these three transgenes were also transformed into tobacco to provide fast-recovering, easy to test transformants to assess the efficacy of the transgenes. Transformed garlic and tobacco lines were analysed to assess the integration and expression of the transgenes, then challenged with Sm. cepivorum or Sa. sclerotiorum, respectively, to assess the bioactivity of recombinant wheat oxalate oxidase, barley oxalate oxidase, and Flammulina oxalate decarboxylase against oxalic acid-dependent pathogens. Results show that one line of tobacco expressing the Flammulina oxalate decarboxylase enzyme was found to be consistently resistant to Sclerotinia sclerotiorum. Garlic lines transformed with this transgene failed to display stable transgene expression or disease resistance, possibly due to silencing of the transgene in recovered transformant tissue.

Orientador: Nilson Luiz de Souza / Banca: Edson Luiz Furtado / Banca: Yodiro Masuda / Banca: Raquel Ghini / Banca: Walmir Contra de Jesus Junior / Resumo: Os fungos fitopatogênicos habitantes de solo causam grandes perdas em culturas econômicas. Estes organismos, por produzirem estruturas de resistência na ausência de hospedeiros e/ ou condições climáticas desfavoráveis, inviabilizam o controle do patógeno. A preservação de fungos por longos períodos é importante para que pesquisas possam ser realizadas a qualquer tempo. O método de manutenção destes organismos requer que sejam conservados em baixa atividade biológica para preservar as características de esporulação e patogenicidade. O objetivo deste trabalho foi desenvolver metodologias para produzir, avaliar a sobrevivência e preservar as estruturas de resistência dos fungos Fusarium oxysporum f.sp. lycopersici raça 2, Macrophomina phaseolina, Rhizoctonia solani GA4 HGI, Sclerotium rolfsii, Sclerotinia sclerotiorum e Verticillium dahliae. O primeiro experimento foi feito no delineamento de parcelas inteiramente casualizadas em que a sobrevivência das estruturas de resistência dos seis fungos foi avaliada mensalmente por seis meses, em condições de campo e de laboratório. Para tanto, estruturas de cada fungo, produzidas através das metodologias desenvolvidas, foram enterradas no campo a 10 cm de profundidade e outras mantidas no laboratório. O objetivo deste experimento foi verificar a eficiência das metodologias para manter e também para avaliar a capacidade da sobrevivência dos patógenos, permitindo desta forma, manusear as estruturas de resistência de todos os fungos estudados. No segundo experimento, frascos de 500 mL (duas repetições/fungo) contendo estruturas de resistência, produzidas através das 2 metodologias desenvolvidas, foram mantidos em temperatura natural de laboratório, de refrigeração (º5C) e de freezer (-20ºC) para determinar a melhor condição para preservar as estruturas de cada fungo...(Resumo completo, clicar acesso eletrônico abaixo) / Soilborne phytopathogenic fungi cause great losses in economical cultures. These organisms produce resistance structures in the absence of hosts and / or unfavorable climatic conditions. These structures, when presents, make unfeasible the pathogen control. The preservation of fungi for long periods is important to make possible researches the any time. The method of maintenance of these organisms requests that are conserved in low biological activity to preserve the sporulate characteristics and pathogenicity. The objective of this work was to develop methodologies to produce and to evaluate the survival and also to preserve the resistance structures of Fusarium oxysporum f.sp. lycopersici race 2, Macrophomina phaseolina, Rhizoctonia solani AG4 HGI, Sclerotium rolfsii, Sclerotinia sclerotiorum and Verticillium dahliae. The first experiment was carried out in a randomized plots design where the survival of the resistance structures of the six fungi was monthly evaluated for six months under field and laboratory conditions. The structures of each fungus, produced through the developed methodologies, were buried in the field at 10 cm of depth and another maintained at the laboratory. The objective of this experiment was to verify the efficiency of the methodologies to maintain and also to evaluate the survival capacity of the pathogens in order to set methodologies to handle the resistance structures of those fungi. In the second experiment 500 mL flasks (two repetitions/fungus) containing resistance structure produced through developed methodologies were maintained at room, refrigerator and freezer temperature to determine the best condition to preserve the structures those pathogens. Monthly and for a period of 4 one year the survival and the vigour of each pathogen were evaluated on their specific medium...(Complete abstract click electronic access below) / Doutor

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-23T16:29:21Z No. of bitstreams: 1 Yrlania de Lira Guerra.pdf: 709734 bytes, checksum: 3d0f17731c8fae1c2730d371c8128560 (MD5) / Made available in DSpace on 2017-03-23T16:29:21Z (GMT). No. of bitstreams: 1 Yrlania de Lira Guerra.pdf: 709734 bytes, checksum: 3d0f17731c8fae1c2730d371c8128560 (MD5) Previous issue date: 2013-02-26 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Brazil is a major producer of world agricultural production is limited by pests and diseases. Among the diseases Sclerotium rolfsii Sacc. is a fungus that causes major losses in agriculture by presenting more than 500 hosts and is present in all tropical regions. The effect of essential oils in control of wilt sclerotia, culture as having reference to the peanut crop, with subsequent recommendation in agricultural management, with a segment phytopathological. Using four different isolates of S. rolfsii was conducted mycelial growth rate, followed by the pathogenicity test in the peanut plants (cultivar BR 1), the SR5 was isolated which had the highest growth rate and more aggressive. The seven essential oils were selected for bioassay of inhibition at concentrations previously established, with the reference dosage of 1000 ppm. Being selected again at low concentrations, from 500 ppm, Palmarosa oil which was showed the highest inhibition rate of formation of sclerotia, the lowest dose tested that was 300 ppm. In the test of suppression of diffusion of oxalic acid was performed with the more aggressive isolated (SR5) with palmarosa oil at 400 ppm, which reduced the rate of mycelial growth by 55%. The bioassay establishment of the pathogen in the substrate and pathogenicity in peanut genotypes in a greenhouse with two genotypes, BR 1 and Senegal. The assay was performed with substrate Baseplant being added 40 g de P2O5 + 15 g KCl + 200 g de humus/kg substrate fertilized. BR Genotype 1 was more susceptible than Senegal, isolated SR5 was more aggressive, leading to higher rates of disease when grown only in substrate. In the validation assay of the oil against S. rolfsii in the greenhouse, was held with seven treatments and at the end of the cycle there was a weight gain of 54% of the pods, 57% in the number of pods/plant and harvest index of 40%. / O Brasil é um dos maiores produtores agrícolas mundiais do amendoim e sua produção é limitada por pragas e doenças. Dentre as doenças, destaca-se a murcha de esclerócio que causa grandes perdas na agricultura por apresentar mais de 500 hospedeiros e estar presente em todas as regiões tropicais. Avaliou-se o efeito dos óleos essenciais no controle da murcha de esclerócio tendo como cultura de referência ao amendoim. Foram testados quatro isolados de Sclerotium rolfsii avaliando-se a sua taxa de crescimento micelial em BDA (batata, dextrose e ágar) e patogenicidade no amendoim (cv. BR 1). O isolado SR5 foi o que apresentou a maior taxa de crescimento e o mais agressivo. Os sete óleos essenciais foram selecionados pela realização do bioensaio de inibição, com concentrações previamente estabelecidas, tendo como dosagem referencial 1000 ppm. Sendo novamente selecionados a baixas concentrações, a partir de 500 ppm. O óleo de Palmarosa foi o que apresentou a maior taxa de inibição de formação de esclerócios, na menor dose testada (300 ppm). O teste de supressão da difusão do ácido oxálico, foi realizado com o isolado mais agressivo (SR5), com o óleo de Palmarosa a 400 ppm, o qual reduziu a taxa de crescimento micelial em 55%. Para o teste de estabelecimento do patógeno no substrato Baseplant e de patogenicidade nos genótipos de amendoim em casa de vegetação utilizou-se dois genótipos, BR 1 e Senegal. O ensaio realizado com substrato recebeu adição de 40 g de P2O5 + 15 g KCl + 200 g de húmus/Kg como adubação básica. O genótipo BR 1, foi mais suscetível que Senegal, o isolado SR5 mostrou-se mais agressivo, provocando maior índice de doença quando cultivado apenas em substrato. O ensaio de validação do óleo contra S. rolfsii em casa de vegetação, foi realizado com sete tratamentos e ao final do ciclo da cultura observou-se um ganho de 54% no peso das vagens, 57% no número de vagens/planta e 40% no índice de colheita.

Allium sativum and Tulbaghia violacea are some of the most important medicinal plants used by South African traditional healers for the treatment of flu, fever, cold, tuberculosis, asthma and many more diseases. However, growth, yield and quality are constrained by excessive and under fertilization. This study was carried out to determine, firstly, the effect of N source (ammonium sulphate and calcium nitrate) on yield and quality of A. sativum and T. violacea plants. Secondly, to determine the best season for harvesting T. violacea and lastly, to determine the antifungal effects of A. sativum and T. violacea plant extracts against plant pathogens Altenaria solani and Sclerotium rolfsii. Both plants were treated with both N sources applied as topdressing treatments at a total of 0, 50, 100, 150 and 200 kg.ha-1, divided into three applications at three week (A. sativum) and three month (T. violacea) intervals. A. sativum plants were sampled at 54, 82, 112, 140 and 175 days after planting (DAP) while, T. violacea plants were sampled monthly for ten months. Parameters recorded were growth analysis, yield and bioactivity for both plant species. Both nitrogen sources improved plant growth and yield of A. sativum and T. violacea plants. Calcium nitrate at 150 kg•ha-1 and ammonium sulphate at 200 kg•ha-1 produced the highest at 24 t•ha-1 and 27 t•ha-1, respectively. Ammonium sulphate improved bioactivity of leaves with the highest bioactivity recorded at 82 and 112 DAP. Yield obtained from the autumn harvest was not affected by N source. Ammonium sulphate and calcium nitrate at 200 kg•ha-1 produced the highest yields of 23.6 t•ha-1 and 23.5 t•ha-1, respectively. In contrast, yield obtained from the winter harvest was affected by N source at 200 kg•ha-1, with significantly better yield of 30.8 t•ha-1 with calcium nitrate compared to 27.4 t•ha-1 with ammonium sulphate. Crude extracts of T. violacea bulbs that were treated with ammonium sulphate significantly inhibited the growth of plant pathogenic fungi, whereas extracts from plants treated with calcium nitrate showed low bioactivity. Extracts from plants grown with ammonium sulphate at 100 kg•ha-1 were more effective in controlling growth of plant pathogens when compared to other N levels. The minimum inhibitory concentration (MIC) effects of A. sativum against S. rolfsii and A. solani were at 0.01 mg•mL-1. The MIC of T. violacea extracts against A. solani was at 0.006 mg•mL<Sup>-1. The MIC of T. violacea extracts were better than previously reported in literature. Therefore, A. sativum and T. violacea plant extracts can be used as fungicides against S. rolfsii and A. solani diseases for crops such as tomato and potato. / Dissertation (MInstAgrar)--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted

Sclerotinia blight, caused by <i>Sclerotinia minor</i>, is a severe disease of peanut in Virginia. Vinclozolin (V), iprodione (I), dicloran (D), and pentachloronitrobenzene (PCNB) were evaluated for their fungitoxicity to <i>S. minor</i>. The mean ED₅₈ values for five isolates were found to be 0.07, 0.11, 0.91, and 1.27 μg/ml, for V, I, D, and PCNB, respectively, on fungicide-amended glucose yeast-extract agar (GYEA). Fungicide-resistant growth sectors developed on media amended with I or V. Nine such strains occurred; they were capable of growth on GYEA amended with up to 1000 μg/ml of I or V, and were cross-resistant to D or PCNB. Resistance was maintained in all but two strains after repeated culture in the absence of fungicide for 3 yr. In field microplots, two resistant strains were pathogenic to peanut and survived as well as a fungicide-sensitive field isolate. D, I and V were applied to peanuts in the microplots for 3 yr at total annual rates of 8.41, 3.36, and 2.52 kg/ha, respectively. Disease severity caused by the resistant strains was suppressed 19, 33, and 87% by D, I, and V, respectively, as compared to 15, 24, and 76% for the sensitive isolate. Isolates recovered from tissue biopsies still grew on fungicide-amended GYEA indicating that <i>in vitro</i> and <i>in vivo</i> resistance are not equivalent in this case. Fungicide treatments reduced sclerotial populations of all strains, and reduced the viability of sclerotia from sensitive but not resistant strains. Fungicide-resistant strains were capable of surviving and competing pathogenically in microplots infested with equal numbers of sclerotia from a sensitive and a resistant strain; this trend was enhanced by fungicide applications. A survey of 763 isolates from fields treated with these fungicides failed to detect resistant strains. One fungicide-resistant isolate was recovered from an iprodione-treated microplot originally infested with a sensitive field isolate. A technique utilizing excised peanut stems was devised to evaluate isolate pathogenicity, cultivar resistance to the disease, susceptibility of different age peanut tissues, and fungicide persistence on peanut stems in the field. The method was also used to screen fungicides; results verified previous findings which indicated that <i>in vitro</i> resistance is not equivalent to <i>in vivo</i> resistance. Resistance to these fungicides may eventually become a field problem, but with correct management they should provide years of disease control. / Ph. D. / incomplete_metadata