989 resultados para PLANT-PATHOGENS
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Despite the importance of plant pathogens belonging to the Order Pucciniales (=Uredinales), popularly called rusts, certain peculiarities of its biology is poorly known, mainly due to the difficulty of growing them in culture media and also by the lack of appropriate methodologies for the development of research. Therefore, this study was to verify the efficiency of apparatus called germinatelia to obtain data about the basidiospores production biology of different Pucciniales species. Were used in the study Puccinia pampeana, P. psidii, P. pelargonii-zonalis, P. arachidis, P. mogiphanis, P. emiliae, P. hetereospora, P. malvacearum and P. cnici-oleracei. The use of germinatelia have revealed high basidiospores production for a period up to 5 months at temperatures between 12 degrees and 21 degrees C. Furthermore, in P. malvacearum was possible to record the germination by repetition (survival strategy) in 4.5% of basidiospores produced. All species were favored to mild temperatures. These results therefore demonstrate that the use of germinatelios is efficient, assisting in obtaining data about the biology and cycles of different Puccinia species, enabling better understanding of these pathogens, resulting in management and control measures most appropriate/accurate.
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Leafcutter ants are considered pests in agriculture for their impact in human crops, as they behave utilizing foliar fragments to raise their simbiont fungi (Agaricales: Lepiotaceae) inside their nest. Recent studies have noticed that other fungi may be associated to ants inside their nests, for instance, fungi with melanized wall, known by “dematiaceous”. Historically, many black fungi have been noticed as fitopathogens of many plant cultures with economic importance, highlighting dematiaceous ecological behavior importance in this study. This investigation had the purpose of amplifying ecological knowledge of this fungi, isolating and identificating dematiaceous fungi found in Attini nests, having the intention of understanding plant pathogens dispersion by ants. In this work, 66 isolates were characterized in the following genus: Aspergillus, Penicillium, Paecilomyces, Oxyporus, Rhodotorula, Bipolaris, Curvularia, Fusarium, Giberella, Paraphaeosphaeria, and Cladosporium. The genus Bipolaris, Curvularia, Fusarium and Giberella are known for their opportunistic behaviour, with some published human infections in literature. Fusarium is a notorious fitopathogen, with wide number of descriptions and studies involving pathogenicity development, biochemistry and genetics. The isolates outline is of phyto – associated (phytopathogens, endophytic or epiphitic), fulfilling this work intention in alarming fungi capacity of dispersal by ants. The comprehension of phytopathogenical processes may be clarified based on the knowledge of oportunistics fungi that may utilize ants bodies for their own dispersal. The identification of isolates with capacity of infecting humans brings out public health issues.
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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV
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Human activities are altering the concentrations of ozone in the troposphere and hence in the incidence of ultraviolet-B (UV-B) on Earth’s surface. Although representing only five percent of UV-B radiation striking the Earth's surface, this radiation has the potential to cause effects on biologically active molecules. Sensitivity to UV-B radiation is one of the limitations of biological control of plant pathogens in the field. The objectives of this work were to evaluate the effects of UV-B on several isolates of Clonostachys rosea, and the ability of an isolate of C. rosea, previously selected for its tolerant to UV-B radiation, to control Botrytis cinerea on strawberry leaves in controlled conditions (strawberry leaf discs). The germination of C. rosea conidia was inversely proportional to the irradiance. The most tolerant strain (LQC62) had relative germination of about 60% after irradiation of 4.2kJ/m2, and this strain was selected to be used in the subsequent studies. The data showed that even with exposure to UV-B radiation, C. rosea LQC62 controlled the pathogen. Conidial concentrations of strain LQC62 above 105 conidia/ml showed higher tolerance to UV-B radiation and increased ability to control more than 75% of the B. cinerea even with exposure to radiation. According to our results, in addition to showing less growth under UV-B, conidia of C. rosea had lower antagonistic ability. Further studies are needed to observe the tolerance of B. cinerea conidia to UV-B radiation and thereby prove that an environment with increased UV-B radiation may be favoring the pathogen due to a lower ability of C. rosea to control the pathogen in conditions of increased UV-B.
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Usage of pesticies in excessive doses or in an inadequate way to control diseases, pests and weeds, has promoted significant environmental damage, contamination of animals, intoxication of farmers, among others. These factors lead to occur the resistance of weeds, pests and pathogens, the appearance of iatrogenic diseases, biological imbalance and reduction in biodiversity. Seeking less aggressive alternatives, plant extracts have been used successfully. Compared to synthetic products, they offer great advantages as generating new compounds, which pathogens are unable to inactivate, and are less toxic, of rapid degradation in the environment, they have broad modes of action, and are derived from renewable resources. It should be emphasized that there are some limitations on its use. The extracts have potencial as insecticide, fungicide, herbicide and nematicide and are considered of good efficiency. The methodologies for obtaining can be achieved through cold extraction, open and closed hot system. The use of plant extracts reappears as a promising and unique option for integrated management in plant protection, being considered as an alternative to control plant pathogens, demonstrating excellent results without causing harm to the environment and living beings.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)