88 resultados para Bipolaris


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The use of fungicides for treating seeds has become an essential measure in the control of pathogens. However, the effectiveness of many products is not well-known to some crops. The objective of this research was to evaluate the effect of different doses of carbendazin and carboxin + thiram fungicides for controlling pathogens and their interference on the physiologic quality of castor bean seeds. The test consisted of the following treatments (g i.a./100 kg of seeds): carbendazin (15, 30, and 60), carboxin + thiram (25 + 25, 50 + 50, and 100 + 100), formol 0.15% (v/v), and control (distilled water). The physiologic quality of the seeds was determined by germination, first counting, field emergence, speed emergence index, length, fresh and dry weight of the aerial part, and electrical conductivity. There were no statistical differences for germination and fresh and dry matter index. The treatment with formol provided lower values for first counting and field emergence. Seeds treated with fungicides presented higher values for electrical conductivity, but did not differ, statistically, among themselves. The fungi Cladosporium spp.; Bipolaris spp.; Curvularia spp.; Aspergillus flavus; Aspergillus niger; Rhizopus sp.; Penicillium sp.; Rhizoctonia sp.; Verticillium sp.; Fusarium sp.;Arthrobotrys sp.; and Epicocum sp. were identified. All tested products, independently of the dose, provided efficient control for pathogens.

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Palm trees belong to the Arecaceae family and are widely utilized in landscaping of tropical countries. Although there are many species, just a few are used in Brazil's landscaping, the majority coming from other countries. So, this study had the objective to characterize the plants in the collection of palm trees at UNESP/FCAV, Campus of Jaboticabal, Sao Paulo State, Brazil. The germination of seeds was also studied to increase the production of seedlings for use in landscaping, as this is the biggest difficulty for spreading new species. The introduction of new species in the collection was accomplished. It was also made a survey of major pests and diseases that occur in the collection. The most common pests found were: Brassolis sophorae, Parisoschoenus obesulus, Rhynchophorus palmarum and Coraliomela sp., and the most common disease causing fungi: Colletrotrichum sp., Curvularia sp., Bipolaris sp., Helminthosporium sp., Alternaria sp., Phyllosticta sp., Pestalotia sp., Exosporium palmivorum and Ceratocystis pardoxa.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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This study aimed to assess the incidence of fungi and nematodes in Brachiaria sp. and Panicum maximum seeds produced in the Brazilian states of Mato Grosso do Sul (MS), Mato Grosso (MT), Goiás (GO), Minas Gerais (MG) and São Paulo (SP). The main fungi found in the seeds were Bipolaris sp., Curvularia sp. and Phoma sp.. The lowest incidence of these fungi was found for seeds of Brachiaria brizantha cultivars BRS Piatã and Xaraés, and Brachiaria decumbens cv. Basilisk, from the states of GO, MG and MS, respectively. The cultivars Marandu and BRS Piatã, from several regions, exhibited high occurrence of Aphelenchoides sp. and Ditylenchus sp.. Seeds of B. humidicola cultivar Humidicola, produced in MS and SP, did not show association with nematodes. The seeds of Panicum maximum cv. Massai and cv. Mombaça showed higher incidence of Bipolaris sp., Cladosporium sp., Curvularia sp., Fusarium sp. and Phoma sp., as well as Aphelenchoides sp. and Ditylenchus sp., especially for seeds produced in MT. Some of the detected pathogens are causative agents of diseases of major importance in forage plants, such as Bipolaris sp., causing leaf spot in Panicum, of high severity in Tanzânia, which provides serious compromising of the pasture sustainability.

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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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Live (Rose Bengal stained) and dead benthic foraminiferal communities (hard-shelled species only) from the Pakistan continental margin oxygen minimum zone (OMZ) have been studied in order to determine the relation between faunal composition and the oxygenation of bottom waters. During R.R.S. Charles Darwin Cruises 145 and 146 (12 March to May 28 2003), 11 multicores were taken on the continental margin off Karachi, Pakistan. Two transects were sampled, constituting a composite bathymetric profile from 136 m (above the OMZ in spring 2003) down to 1870 m water depth. Cores (surface area 25.5 cm2) were processed as follows: for stations situated above, and in the upper part of the OMZ, sediment slices were taken for the 0-0.5 and 0.5-1 cm intervals, and then in 1 cm intervals down to 10 cm. For the lower part of the OMZ, the second centimetre was also sliced in half-centimetre intervals. Each sample was stored in 10 % borax-buffered formalin for further processing. Onshore, the samples were wet sieved over 63 µm, 150 µm and 300 µm sieves and the residues were stained for one week in ethanol with Rose Bengal. After staining, the residue was washed again. The stained faunas were picked wet in three granulometric fractions (63-150 µm, 150-300 µm and >300 µm), down to 10 cm depth. To gain more insight into the population dynamics we investigated the dead (unstained) foraminifera in the 2-3 cm level for the fractions 150-300 µm and >300 µm. The fractions >300 µm and 150-300 µm show nearly the same faunal distribution and therefore the results are presented here for both fractions combined (i.e. the >150 µm fraction). Live foraminiferal densities show a clear maximum in the first half centimetre of the sediment; only few specimens are found down to 4 cm depth. The faunas exhibit a clear zonation across the Pakistan margin OMZ. Down to 500 m water depth, Uvigerina ex gr. U. semiornata and Bolivina aff. B. dilatata dominate the assemblages. These taxa are largely restricted to the upper cm of the sediment. They are adapted to the very low bottom-water oxygen values (ab. 0.1 ml/l in the OMZ core) and the extremely high input of organic carbon on the upper continental slope. The lower part of the OMZ is characterized by cosmopolitan faunas, containing also some taxa that in other areas have been described in deep infaunal microhabitats.

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Long-term evolution is thought to take opportunities that arise as a consequence of mass extinction (as argued, for example, by Gould, 2002) and the following biotic recovery, but there is absolutely no evidence for this being the case. However, our study shows that eutrophication by oceanic mixing also played a part in the enhancement of several evolutionary events amongst marine organisms, and these results could indicate that the rates of oceanic biodiversification may be slowed if upwelling becomes weakened by future global warming. This paper defines three distinct evolutionary events of resting spores of the marine diatom genus Chaetoceros, to reconstruct past upwelling through the analysis of several DSDP, ODP and land-based successions from the North, South and equatorial Pacific as well as the Atlantic Ocean during the past 40 million years. The Atlantic Chaetoceros Explosion (ACE) event occurred across the E/O boundary in the North Atlantic, and is characterized by resting spore diversification that occurred as a consequence of the onset of upwelling following changes in thermohaline circulation through global cooling in the early Oligocene. Pacific Chaetoceros Explosion events-1 and -2 (PACE-1 and PACE-2) are characterized by relatively higher occurrences of iron input following the Himalayan uplift and aridification at 8.5 Ma and ca. 2.5 Ma in the North Pacific region. These events not only enhanced the diversification and increased abundance of primary producers, including that of Chaetoceros, other diatoms and seaweeds, but also stimulated the evolution of zooplankton and larger predators, such as copepods and marine mammals, which ate these phytoplankton and plants. Current thinking suggests new evolutionary niches open up after a mass extinction, but our study finds that eutrophication can also stimulate evolutionary diversification. Moreover, in the opposite fashion, our results show that as thermohaline circulation abates, global warming progresses and the ocean surface becomes warmer, many marine organisms will be affected by the environmental degradation.

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The Paleocene/Eocene boundary was recovered for the first time in diatom-bearing sediments at Broken Ridge, Site 752. Diatom assemblages are documented throughout the 180-m-thick sequence of upper Paleocene to lower Eocene sediments. Age control available from magnetostratigraphy, calcareous nannofossils, and planktonic foraminifers allows calibration of diatom datum levels to absolute time. A partly new/partly revised diatom zonation is proposed for the Paleocene/early Eocene based on the results of Site 752 and consideration of other studies. The diatom zones are defined as follows (from the youngest to the oldest): Pyxilla gracilis Zone (first occurrence of Craspedodiscus undulatus to first occurrence Pyxilla gracilis); Hemiaulus incurvus Zone (first occurrence Pyxilla gracilis to first occurrence Hemiaulus incurvus); Hemiaulus peripterus Zone (first occurrence Hemiaulus incurvus to first occurrence Hemiaulus peripterus var. peripterus). Three new taxa are described: Anaulus fennerae n. sp., Stictodiscus bipolaris n. sp., and Hemiaulus peripterus var. longispinus n. var.