Made available in DSpace on 2017-07-10T17:37:06Z (GMT). No. of bitstreams: 1 Camila Peiter Beninca.pdf: 379262 bytes, checksum: 2683f759673a0f79789d731e9e40a850 (MD5) Previous issue date: 2007-05-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The induced resistance is an alternative for control of plant diseases, because the incorrect use of chemical products have been caused several problems to the environment. With the induced resistance, plants can produce secondary compounds, as the phytoalexins with antimicrobial activity. Additionally, peroxidases can be activated, causing cell walls reinforcement, through the formation of lignin that blocking the attack of pathogens. The resistance induced can be carried through by several substances, as secondary compounds produced by fungus, as the Basidiomycota Pycnoporus sanguineus. This work aimed to verify the phytoalexins induced and the peroxidases activity in sorghum and soybean treated with P. sanguineus basidiocarp extracts. With this purpose, the dichloromethanic, hexanic and ethanolic extracts, in concentrations of 100, 250, 500 and 750 mg L-1 were used for phytoalexins production and peroxidases activity in soybean cotyledons and sorghum etiolated mesocotyls. The acybenzolar-S-metil (ASM) (100 mg L-1 of active ingredient) and distilled water + Tween 20 (0.5%) were used as positive and negative patterns, respectively. For the phytoalexins assay in sorghum mesocotyls, the hexanic extract in concentration of 750 mg L-1 provided the highest induction in comparison to the control with water, however without differences to ASM. For the phytoalexins assay in the soybean cotyledons, the P. sanguineus extracts not induced activity significantly different of the positive and negative patterns, but also causing a suppression of the glyceollin synthesis for the dichloromethanic extract. In relation to the peroxidases activity, the dichloromethanic extracts for sorghum and soybean and ethanolic for soybean had inhibited the enzymatic activity. The induction verified for the hexanic extract in sorghum was not different from ASM control. The specific activity of peroxidase in soybean was inhibited by the ethanolic extract and it was induced by the hexanic, but with no differences of the treatment with ASM. These results indicate the weak potential of these extracts for the resistance induction in sorghum and soybean / A indução de resistência em plantas ganhou destaque como alternativa no controle de doenças em decorrência dos problemas do uso indevido de produtos químicos. Através desta técnica, algumas plantas respondem com a produção de compostos secundários, como as fitoalexinas, que são substâncias capazes de impedir a atividade de agentes causadores de doenças. Além destas, há a ativação de peroxidases que contribuem no fortalecimento das paredes celulares, pela formação de lignina em resposta ao ataque de patógenos, bloqueando a entrada do agente causador da doença. A indução de resistência pode ser realizada por diversas substâncias, como os compostos secundários presentes nos fungos, tendo como exemplo o Basidiomycota Pycnoporus sanguineus. Este trabalho teve como objetivo avaliar a indução de fitoalexinas e a atividade de peroxidases em sorgo e soja tratados com extratos de basidiocarpos de P. sanguineus. Com essa finalidade, os extratos diclorometânico, hexânico e etanólico nas concentrações de 100, 250, 500 e 750 mg L-1 foram testados em relação à produção de fitoalexinas e atividade de peroxidases em cotilédones de soja e mesocótilos estiolados de sorgo. Acibenzolar-S-metil (ASM) (100 mg L-1 i.a.) e água destilada + Tween 20 (0,5%) foram utilizados como tratamentos controle positivo e negativo, respectivamente. Para o ensaio de fitoalexinas em mesocótilos de sorgo, o extrato hexânico na concentração de 750 mg L-1 proporcionou a maior indução, sendo estatisticamente superior à testemunha negativa, porém sem diferir significativamente do ASM. Para fitoalexinas em cotilédones de soja, os extratos de P. sanguineus não induziram atividade significativamente diferente dos tratamentos controles positivo e negativo, havendo inclusive uma tendência de supressão da síntese de gliceolina pelo extrato diclorometânico. Em relação à atividade de peroxidases, os extratos diclorometânico para sorgo e soja e etanólico para soja inibiram a atividade enzimática. A atividade específica de peroxidase em soja foi inibida pelo extrato etanólico e induzida pelo hexânico, mas sem diferença do tratamento com ASM. Esses resultados indicam o pequeno potencial destes extratos para a indução de resistência em sorgo e soja

Made available in DSpace on 2014-06-11T19:28:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-07Bitstream added on 2014-06-13T18:35:01Z : No. of bitstreams: 1 silva_aca_me_botfca.pdf: 486573 bytes, checksum: 7da2829da43c73fb9381ae790a958b36 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Atualmente diversos estudos têm sido desenvolvidos sobre a utilização dos silicatos na adubação de plantas e embora ainda não conclusivos, seu emprego tem sido intensificado em algumas regiões agrícolas do país. No entanto, como o silício não é considerado um nutriente essencial de plantas, uma das principais justificativas para seu emprego na agricultura tem sido o incremento da resistência a pragas e doenças. Dessa forma, foram instalados dois experimentos seguindo o delineamento experimental de blocos ao acaso para verificar o efeito do silício sobre a lagarta-do-cartucho do milho em condições de campo. O primeiro experimento foi composto por 10 tratamentos e 4 repetições, com parcelas de 10 linhas de 10 m e visou verificar o efeito de uma formulação comercial contendo 25% de óxido de silício (12% de Si solúvel) e 15% de óxido de potássio, desenvolvida para aplicação através da pulverização foliar. Os tratamentos no primeiro experimento consistiram da aplicação da formulação silicatada nas concentrações 2, 4 e 8 mL/L, em pulverização aos 15, aos 15 e 30 e aos 15, 30 e 45 dias após a germinação das plantas. O segundo experimento contou com 7 tratamentos e 4 repetições, com parcelas de 7 linhas de 10 m e visou verificar o efeito de uma formulação comercial constituída por escória de siderurgia, aplicada no sulco de semeadura, nas doses de 400 e 800 kg/ha, na semeadura, só na cobertura, e na semeadura e cobertura. Nos dois experimentos avaliou-se a incidência da lagarta-do-cartucho do milho aos 15, 30, 45 e 60 dias após a germinação e os respectivos danos através de uma escala de notas. Também foram avaliados os parâmetros vegetativos indicadores do desenvolvimento como, altura da planta; número de folhas vivas; data do fechamento do cartucho e data do lançamento do pendão e o número de espigas produzido. Finalmente foi a avaliada... / At present several studies about the use of silicates on plant fertilization have been developed, and although there is nothing conclusive regarding it, their use has been intensified in some Brazilian agricultural regions. However, since silicon is not considered an essential plant nutrient, the main reason for its use in agriculture has been the increase in the plant resistance to pests and diseases. This way, two experiments were carried out to verify the effect of silicon on fall armyworm in field corn. The first experiment used a randomized block design with 10 treatments and 4 replicates and with plots of ten 10 m rows to verify the effect of a commercial formula containing 25% of silicon oxide (12% of soluble Si) and 15% of potassium oxide, developed for foliar application. The treatment on the first experiment consisted of the silicate formula at concentration of 2,4 and 8 mL/L, sprayed at 15 days, at 15 and 30 and at 15, 30 and 45 days after plant germination. The second experiment also used a randomized block design with 7 treatment and 4 replications, and with plots of seven 10m rows, to verify the effect of a commercial formula composed by silicate slag applied in the soil, with dosages of 400 and 800 kg/ha, in the sowing, only in coverage and both. The incidence of fall armyworm was evaluated at 15, 30 45 and 60 days after the germination and its respective damage through a grade scale in both experiments. Vegetation development indicator parameters were also evaluated as: plant height; number of living leaves; date of the flowering; number of corncobs. The production was finally evaluated by weighing the corncobs and grain/plant. The data obtained indicated that silicon did not interfere neither on the plant vegetable development nor in the occurrence of fall armyworm. It did not interfere neither on the damage caused by this pest, nor on the number of and grains produced.

Master of Science / Department of Entomology / John C. Reese / The soybean aphid, Aphis glycines is documented to have arrived in North America in mid 2000 and has ever since established itself as a formidable pest of soybeans, with the capacity to cause immense crop losses. This formidable pest with its complex life cycle and habits represents a current threat to soybean production. Host plant resistance is a promising avenue that can offer considerable control over the soybean aphid problem. Antibiosis being the most effective host plant resistance category, this study was aimed at attempting to understand the effects of induction on the antibiosis levels of soybeans. In the first set of experiments, different soybean genotypes and two soybean aphid biotypes were tested to comprehend if and how the genotypes and biotypes affected the survival and reproduction of the aphid. The experiments revealed mixed results that can be attributed to the genotypes tested and the biotypes used. While some genotypes showed no significant changes due to previous infestation, K1621 suggested signs of induced resistance to biotype 1 and PI567301B showed induced resistance to biotype 2, while K1639 pointed towards induced susceptibility to biotype 2. A follow up feeding behavior study with Electrical Penetration Graph (EPG) technique was carried out on PI567301B to elucidate if the induced resistance was tissue-specific, which could affect the feeding behavior of the aphid (biotype 2); but the results showed no appreciable differences in the feeding behavior of the aphids on clean vs. infested plants. Induced response studies shed light on how plants respond to herbivory and help us identify how changes in plant physiology affect the various herbivores that visit it for food and shelter. This knowledge can thus be applied to the development of superior varieties of crops that can defend themselves better against recurring infestations.

Made available in DSpace on 2017-07-10T17:37:46Z (GMT). No. of bitstreams: 1 Sidnei_Francisco_Muller.pdf: 411746 bytes, checksum: 109f8d2944b15744649a1124e0b9809a (MD5) Previous issue date: 2011-06-27 / The use of chemicals as a means of controlling bean diseases is an established practice for the crop. Despite the satisfactory results for most diseases, it is a form of control that can result in serious risk to the environment and human health. Thus, alternative pest control practices have received a great importance, mainly because of its direct applicability for small producers. The alternative control includes biological control and resistance induction, which differs from the first not to act on a specific microorganism, but for providing the plant treated to activate its latent defenses to be prepared when a pathogen trying to infect it. Molecules of biotic and abiotic origin capable of inducing resistance in plants are called elicitors. Among the biotic origin the extracts of yeasts such as Saccharomyces cerevisiae, has been used to induce resistance to control various pathogens from different cultures. S. cerevisiae has been successfully employed, but constantly seeks other organisms capable of use in alternative control. Thus, the yeast Saccharomyces boulardii has been researched to its use in biological control of plant pathogens. In three field assays in dry seasons of 2009 and 2010, and rain season used in 2009, using the bean group Rosinha, was evaluated the effectiveness of the yeast S. boularddi as inducer of resistance and the methabolic cost embedded in it. Foliar applications were carried out with yeast in commercial form, with the mass of cells obtained from the filtering medium YEPG with this yeast and with the filtrate of the medium. The yield, weight of 100 grains, grain number per plant and pods were evaluated. It was noted the low incidence of pathogens in the assays, precluding their measurement by diagrammatic scale. Because the balanced environment, there may have been the biological control of pathogens, the theory of trophobiosis, or even the induction of natural resistance both by microorganisms acting in plants, by rhizobacteria and by the use of biofertilizers leaf. There were no significant differences in parameters, indicating a possible absence of metabolic cost for the application of yeast. This possible fitness cost may have been obscured by the nutritional balance of plants, as well as possible induction in all treatments by local conditions of cultivation and management used. Under agricultural and environmentally balanced nutrition, foliar applications of yeast S. boulardii did not result in apparent metabolic cost / O uso de produtos químicos como forma de controle das doenças do feijoeiro é uma prática consagrada para a cultura. Apesar de apresentar resultados satisfatórios para a maioria das doenças, trata-se de uma forma de controle que pode resultar em sérios riscos ao meio ambiente e a saúde humana. Dessa maneira, práticas de controle fitossanitário alternativas tem recebido maior importância, principalmente pela sua aplicabilidade direta por pequenos produtores. O controle alternativo engloba o controle biológico e a indução de resistência, que difere do primeiro por não agir sobre um microrganismo específico, mas por proporcionar que a planta tratada ative suas defesas latentes para estar preparada quando um patógeno tentar infectá-la. Moléculas de origem biótica e abiótica capazes de induzir resistência em plantas são chamadas elicitores. Dentre os de origem biótica, os extratos de leveduras como Saccharomyces cerevisiae, tem sido empregados como indutores de resistência para o controle de diversos patógenos de diferentes culturas. S. cerevisiae já vem sendo empregada com sucesso, mas busca-se constantemente outros organismos com capacidade de utilização no controle alternativo. Assim, a levedura Saccharomyces boulardii vem sendo pesquisada visando seu uso no controle biológico de patógenos de plantas. Em três ensaios de campo, nas safras das secas de 2009 e 2010, e das águas de 2009, utilizando o feijoeiro do grupo Rosinha, avaliou-se a possível eficiência da levedura S. boularddi como indutor de resistência e o custo adaptativo. Realizaram-se aplicações foliares com a levedura na sua forma comercial, com a massa de células obtida da filtragem do meio de cultura YEPG com essa levedura e com o filtrado desse meio. Foram avaliados a produtividade, massa de 100 grãos e número de grãos e vagens por planta. Constatou-se a baixa incidência de patógenos nos ensaios, impossibilitando sua mensuração por escala diagramática. Em virtude de ambiente em equilíbrio, pode ter havido o controle biológico dos patógenos, a teoria da trofobiose, ou mesmo a indução natural de resistência tanto por microrganismos atuantes nas plantas, por rizobacterias e pelo uso de biofertilizantes foliares. Não foram observadas diferenças significativas nos parâmetros avaliados, evidenciando possível ausência de custo metabólico pela aplicação da levedura. Esse possível custo adaptativo pode ter sido ocultado pelo estado nutricional equilibrado das plantas, assim como por possível indução de resistência em todos os tratamentos pelas condições locais de cultivo e manejos empregados. Em condições agrícolas nutricional e ambientalmente equilibradas, aplicações foliares da levedura S. boulardii não resultam em custo energético aparente

<p><i>Paenibacillus polymyxa</i> belongs to the group of plant growth promoting rhizobacteria (PGPR). Activities associated with <i>P. polymyxa</i>-treatment of plants in earlier experiments include, e.g., nitrogen fixation, soil phosphorus solubilization, production of antibiotics, auxin, chitinase, and hydrolytic enzymes, as well as promotion of increased soil porosity. My thesis work showed that, in stationary phase, <i>P. polymyxa</i> released the plant hormone cytokinin isopentenyladenine, in concentrations of about 1.5 nM.</p><p>In a gnotobiotic system with <i>Arabidopsis thaliana</i> as a model plant, it was shown that <i>P. polymyxa</i>-inoculation protects plants; challenge by either the pathogen <i>Erwinia carotovora</i> (biotic stress) or induction of drought (abiotic stress) showed that pre-inoculated plants were significantly more resistant than control plants. By RNA-differential display on RNA from <i>P. polymyxa</i>-treated or control plants, changes in gene expression were tested. One mRNA, encoding ERD15 (drought stress-responsive gene) showed a strong inoculation-dependent increase in abundance. In addition, several biotic stress-related genes were also activated by <i>P. polymyxa</i>. </p><p>Antagonism towards the fungal pathogens <i>Phytophthora palmivora</i> and <i>Pythium aphanidermatum</i> was studied. <i>P. polymyxa</i> counteracted the colonization of zoospores of both oomycetes on <i>A. thaliana</i> roots, and survival rates of plants treated with <i>P. polymyxa</i> were much higher when challenged by <i>P. aphanidermatum</i>. </p><p>Using a green fluorescent protein-tagged isolate of <i>P. polymyxa</i>, colonization of <i>A. thaliana</i> roots was investigated. Two main conclusions can be drawn. Firstly, the bacterium enters the root tissue (but not leaves) and is abundantly present in intercellular spaces. Secondly, the root becomes severely damaged, indicating that – under some conditions – <i>P. polymyxa</i> is a "deleterious bacterium", and in others it promotes growth. Based on work presented in my thesis, I argue that a balance between the activities of a PGPR, the genetic background and physiological state of a plant, and the environmental conditions employed in test systems, ultimately determines the resulting effect. </p>

Paenibacillus polymyxa belongs to the group of plant growth promoting rhizobacteria (PGPR). Activities associated with P. polymyxa-treatment of plants in earlier experiments include, e.g., nitrogen fixation, soil phosphorus solubilization, production of antibiotics, auxin, chitinase, and hydrolytic enzymes, as well as promotion of increased soil porosity. My thesis work showed that, in stationary phase, P. polymyxa released the plant hormone cytokinin isopentenyladenine, in concentrations of about 1.5 nM. In a gnotobiotic system with Arabidopsis thaliana as a model plant, it was shown that P. polymyxa-inoculation protects plants; challenge by either the pathogen Erwinia carotovora (biotic stress) or induction of drought (abiotic stress) showed that pre-inoculated plants were significantly more resistant than control plants. By RNA-differential display on RNA from P. polymyxa-treated or control plants, changes in gene expression were tested. One mRNA, encoding ERD15 (drought stress-responsive gene) showed a strong inoculation-dependent increase in abundance. In addition, several biotic stress-related genes were also activated by P. polymyxa. Antagonism towards the fungal pathogens Phytophthora palmivora and Pythium aphanidermatum was studied. P. polymyxa counteracted the colonization of zoospores of both oomycetes on A. thaliana roots, and survival rates of plants treated with P. polymyxa were much higher when challenged by P. aphanidermatum. Using a green fluorescent protein-tagged isolate of P. polymyxa, colonization of A. thaliana roots was investigated. Two main conclusions can be drawn. Firstly, the bacterium enters the root tissue (but not leaves) and is abundantly present in intercellular spaces. Secondly, the root becomes severely damaged, indicating that – under some conditions – P. polymyxa is a "deleterious bacterium", and in others it promotes growth. Based on work presented in my thesis, I argue that a balance between the activities of a PGPR, the genetic background and physiological state of a plant, and the environmental conditions employed in test systems, ultimately determines the resulting effect.

To understand how plant defensive traits will evolve, we need to consider the biotic context for plant-herbivore interactions. I investigated how predators affect selection on defensive traits in plants. First, I established the timing of resistance in three soybean genotypes. Next, I examined the combined effects of resistance and predators on plant fitness. I reared Mexican bean beetles (MBBs) with or without spined soldier bugs (SSBs) on soybeans with constitutive resistance (CR) or no resistance (NR). SSBs fed more on MBBs that fed on NR than on CR plants, and this translated into an increased fitness benefit from predators for NR plants over CR plants. Selection for some types of resistance in plants should thus be stronger with lower predation rates. Similarly, I reared MBBs with or without SSBs on soybeans with early induced resistance (EI), late induced resistance (LI), or CR. SSBs fed more on MBBs reared on LI plants than on beetles raised on CR plants, but no more on beetles reared on EI plants than on beetles reared on CR plants. LI plants were the only of the three soybean varieties to receive a fitness benefit from predators, which could help explain the evolution of this type of plant defense. The results of both experiments also suggest that predator introductions may be more beneficial to LI or NR crop plants than EI or CR crops. Finally, I present a model that determines the optimum amount of induced resistance (IR) and CR for a plant growing with and without neighbors. Unlike earlier models, our plants have a probability of being attacked that is modified by short- and long-term feedback of plant defenses to herbivores. Higher costs of defense favor IR over CR, while increasing herbivore attack rates or increasing the overall effectiveness of defense results in more CR. Plants with neighbors might be selected to evolve higher or lower levels of CR than if they were growing alone. Adding neighbors also selects for more mixed induced/constitutive strategies for all parameters. Having defended neighbors could thus be part of the reason why plants have evolved such mixed defense strategies. / Dissertation

Soil application of a known activator of Systemic Acquired Resistance (SAR), benzo(1,2,3)thiadiazole-7-carbothioic acid-S-methyl ester (BTH), and Harmonizer, a polychlorinated copper (II) phthalocyanine pigment, reduced severity of Colletotrichum orbiculare in Nicotiana benthamiana by 99% and 38%, respectively. BTH induced expression of nine SAR/progammed cell death-related genes and primed expression of two Induced Systemic Resistance (ISR)-related genes, while Harmonizer induced expression of only one SAR-related gene. Soil application of Harmonizer also reduced severity of Sclerotinia homoeocarpa in Agrostis stolonifera up to 39%, whereas BTH was ineffective. Next generation sequencing identified over 1000 genes in A. stolonifera with two-fold or higher increased expression following Harmonizer treatment relative to a water control, and induced expression of three defense-related genes was confirmed by relative RT-PCR. These results demonstrate that Harmonizer can activate systemic resistance in a dicot and a monocot, but changes in expression of genes indicated that it differed from BTH-activated SAR. / Petro-Canada, Natural Sciences and Engineering Research Council of Canada, Ontario Turfgrass Research Foundation

Made available in DSpace on 2014-06-11T19:33:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-28Bitstream added on 2014-06-13T19:44:37Z : No. of bitstreams: 1 carvalho_prs_dr_jabo.pdf: 817782 bytes, checksum: f660ce8f19f225b54d401b2637051704 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Plantas e extratos vegetais podem apresentar ação antifúngica e de indução de defesa em função da presença de compostos com características elicitoras. Nesse sentido, foram objetivos do trabalho avaliar o efeito antifúngico dos extratos brutos aquosos de alecrim pimenta, nim e urtiga sobre Colletotrichum gloeosporioides; o potencial como elicitores de fitoalexina e o efeito de controle da antracnose em folhas destacadas de cajueiro. Os extratos brutos aquosos em três concentrações (5%, 10% e 15%) foram adicionados ao meio de cultura BDA para avaliar a ação sobre o crescimento micelial e esporulação e ao substrato Ágar-água para avaliar o efeito na germinação dos conídios e formação de apressórios. O potencial elicitor foi investigado em mesocótilos estiolados de sorgo e cotilédones de soja, determinando a capacidade elicitora das fitoalexinas deoxiantocianidina e gliceolina, respectivamente. Alecrim pimenta a 10% e 15% inibiu totalmente o crescimento micelial de C. gloeosporioides, a esporulação e germinação dos conídios. Nim inibiu parcialmente o crescimento micelial, esporulação e germinação dos conídios de forma proporcional à concentração usada. Urtiga estimulou o crescimento micelial, mas inibiu parcialmente a esporulação e a germinação. Apressórios não foram formados na presença dos três extratos brutos aquosos. Apenas alecrim pimenta a 15% mostrou potencial elicitor de deoxiantocianidina em sorgo. Já em soja foi observado potencial elicitor de gliceolina, embora com acentuada variação, tanto pelos três extratos brutos aquosos quanto pelas concentrações estudadas. O controle da antracnose em folhas destacadas de cajueiro foi observado em todas as concentrações dos extratos de alecrim pimenta e nim e, com urtiga a 15%. O maior efeito de controle foi proporcionado, igualmente, pelas concentrações do extrato de alecrim pimenta / The use of plant extracts have shown antifungal and induction of defense due to the presence of compounds with characteristics elicitors. Therefore, the goals were to evaluate the antifungal effect of aqueous extracts of rosemary pepper, neem and nettle on Colletotrichum gloeosporioides and the potential as elicitors of phytoalexin and the effect of control of anthracnose in detached leaves of cashew plant. The extracts of three concentrations (5, 10 and 15%) were added to the culture medium to evaluate the effect on the mycelial growth and sporulation or to the water-agar substrate to evaluate the effect on conidial germination and apressoria formation. The potential elicitor was investigated in etiolated sorghum mesocotyl and soybean cotyledons, determining the ability of the phytoalexin elicitor deoxyanthocyanidin and gliceollin respectively. Rosemary Pepper 10 and 15% completely inhibited the mycelial growth of C. gloeosporioides and sporulation and germination. Nim partially inhibited the mycelial growth, sporulation and spore germination in proportion to the concentration used. Nettle stimulated mycelial growth, but partially inhibited the sporulation and germination. Appressoria were not formed in the presence of the three extracts. Only rosemary pepper 15% showed potential elicitor of deoxyanthocyanidin in sorghum. In soybean, potential elicitor of gliceolina, although with marked variation, was observed so the three extracts as the concentration. Control of anthracnose in detached leaves of cashew plant was observed at all concentrations of extracts of rosemary pepper and neem and nettle to 15%. The biggest effect of control was provided equally by the concentrations of the extract of rosemary pepper

Resumo: Plantas e extratos vegetais podem apresentar ação antifúngica e de indução de defesa em função da presença de compostos com características elicitoras. Nesse sentido, foram objetivos do trabalho avaliar o efeito antifúngico dos extratos brutos aquosos de alecrim pimenta, nim e urtiga sobre Colletotrichum gloeosporioides; o potencial como elicitores de fitoalexina e o efeito de controle da antracnose em folhas destacadas de cajueiro. Os extratos brutos aquosos em três concentrações (5%, 10% e 15%) foram adicionados ao meio de cultura BDA para avaliar a ação sobre o crescimento micelial e esporulação e ao substrato Ágar-água para avaliar o efeito na germinação dos conídios e formação de apressórios. O potencial elicitor foi investigado em mesocótilos estiolados de sorgo e cotilédones de soja, determinando a capacidade elicitora das fitoalexinas deoxiantocianidina e gliceolina, respectivamente. Alecrim pimenta a 10% e 15% inibiu totalmente o crescimento micelial de C. gloeosporioides, a esporulação e germinação dos conídios. Nim inibiu parcialmente o crescimento micelial, esporulação e germinação dos conídios de forma proporcional à concentração usada. Urtiga estimulou o crescimento micelial, mas inibiu parcialmente a esporulação e a germinação. Apressórios não foram formados na presença dos três extratos brutos aquosos. Apenas alecrim pimenta a 15% mostrou potencial elicitor de deoxiantocianidina em sorgo. Já em soja foi observado potencial elicitor de gliceolina, embora com acentuada variação, tanto pelos três extratos brutos aquosos quanto pelas concentrações estudadas. O controle da antracnose em folhas destacadas de cajueiro foi observado em todas as concentrações dos extratos de alecrim pimenta e nim e, com urtiga a 15%. O maior efeito de controle foi proporcionado, igualmente, pelas concentrações do extrato de alecrim pimenta / Abstract: The use of plant extracts have shown antifungal and induction of defense due to the presence of compounds with characteristics elicitors. Therefore, the goals were to evaluate the antifungal effect of aqueous extracts of rosemary pepper, neem and nettle on Colletotrichum gloeosporioides and the potential as elicitors of phytoalexin and the effect of control of anthracnose in detached leaves of cashew plant. The extracts of three concentrations (5, 10 and 15%) were added to the culture medium to evaluate the effect on the mycelial growth and sporulation or to the water-agar substrate to evaluate the effect on conidial germination and apressoria formation. The potential elicitor was investigated in etiolated sorghum mesocotyl and soybean cotyledons, determining the ability of the phytoalexin elicitor deoxyanthocyanidin and gliceollin respectively. Rosemary Pepper 10 and 15% completely inhibited the mycelial growth of C. gloeosporioides and sporulation and germination. Nim partially inhibited the mycelial growth, sporulation and spore germination in proportion to the concentration used. Nettle stimulated mycelial growth, but partially inhibited the sporulation and germination. Appressoria were not formed in the presence of the three extracts. Only rosemary pepper 15% showed potential elicitor of deoxyanthocyanidin in sorghum. In soybean, potential elicitor of gliceolina, although with marked variation, was observed so the three extracts as the concentration. Control of anthracnose in detached leaves of cashew plant was observed at all concentrations of extracts of rosemary pepper and neem and nettle to 15%. The biggest effect of control was provided equally by the concentrations of the extract of rosemary pepper / Orientador: Modesto Barreto / Coorientador: Margarete Camargo / Banca: Luiz Evaldo de Moura Pádua / Banca: Érica Auxiliadora Giacheto Scaloppi / Banca: Rita de Cássia Panizzi / Banca: Antonio Baldo Geraldo Martins / Doutor