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The paper presents fire blight prediction model s and systems, developed in Europe (system BilIing - versions: BOS, BRS, BIS95 and originated from this system: Firescreen, FEUERBRA and ANLAFBRA) and in United States (Californian, system, model Maryblyt and system Cougarblight). Use of above models and systems in various climatic-geographic conditions and comparison of obtained prognostic data to real fire blight occurrence is reviewed. The newest trends in search on improvement of prognostic analyses parameters with their adjustment particular conditions and consideration of infection source occurrence are also sented.
The fire blight bacterium - Erwinia amylovora - was spread to over 40 countries during last 200 years, since it was f or the first time reported on the eastern sea-coast of USA. The main role in dissemination of this pathogen on a long distance play the propagating material and also migratory birds. However, short distance spread of E. amylovora is mainly supported by the insects and weather conditions, such as rain and wind. The list of arthropods associated with fire blight dissemination includes different species of insects and mites, belonging to nearly 80 genera. Some of them carry pathogen on the surface of their body, while the others create infection courts by wounding plants. In early spring the flies (Diptera) feed on bacterial oozes, which appear on the surface of holdover cankers, became contaminated with E. amylovora and could transfer this pathogen to blossoms. Nevertheless, during blossom the main role in fire bight dissemination play the honeybees (Apis mellifera), carrying bacteria from flower to flower. E. amylovora, however, couldn't survive the winter inside beehives, so bee colonies are not considered as a potential source of primary inoculum. After bloom sucking the insects, especially aphids (Aphididae), leafhoppers (Jassidae), psyllas (Psyllidae) and plant bugs (Lygus spp.), injuring plants create infection courts for bacteria spread by the weather conditions. They also contact with E. amylovora feeding on infected shoots and then could transfer pathogen, on or inside their bodes, to the healthy shoots or plants, but efficiency of this way of infection is controversial.
Fire blight caused by Erwinia amylovora is the most destructive disease affecting apple (Malus x domestica Borkh.), pcar (Pyrus communis L.) and number of other plant species mainly of the Rosaceae family. However, the symptoms of various diseases, either of biotic or abiotic origin, might be mistaken for those of fire blight. Therefore, in almost all cases its diagnostics should be based on etiological studies. For this purpose the classical procedure consisting in isolation of bacteria on selective or semi selective media and determination of pathogenicity of bacteria with morphology similar to E. amylovora is most often applicd. Lately, the serological methods, ecspecially ELISA and immunofluorescence, have been introduced to routine use in laboratories of Polish Plant Protection Service (PPS). However, the highest sensitivity and specificity offer the methods based on analysis of genetic material of the bacteria: hybridization of nucleic acids and polymerase chain reaction (PCR). When required, two PPS laboratories use a PCR-based method. The paper reviews research on application of molecular methods for detection of E. amylovora in plant material, its identification and determination of genetic diversity among the strains originating from various plant species and various geographic regions.
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