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Fireblight, caused by the bacterium Erwinia amylovora , was observed in Israel for the first time in 1985. Primarily, the disease affected several pear orchards. The pathogen was also isolated and identified from symptomatic tissue of apple and cotoneaster. The occurrence, severity and distribution of the disease in 1985 is discussed in relation to environmental conditions and horticultural practices. Although fireblight was widespread in 1985, overall damage from the disease was limited. Actions taken to confirm the presence of fireblight and to manage the disease during its first season of occurrence are discussed. Prospects for the occurrence of fireblight in Israel in the future are discussed and specific recommendations for management of the disease are presented. Based on its behaviour in other countries, fireblight is expected to become established in Israel and the disease will require constant management to minimize losses. 相似文献
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A dieback of Acacia mearnsii trees was observed in the Mkomasi river valley, Natal Province, South Africa. A fungus, tentatively identified as Ceratocystis fimbriata , was consistently isolated from affected twigs and branches. Reinoculation of the pathogen resulted in the development of typical wilt and dieback of A. mearnsii seedlings and saplings and in a dieback of Protea cynaroides plants. This is the first report of this disease in South Africa. 相似文献
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试验分析了梨火疫病菌(Erwinia amylovora)Ea273基因组上新的T3SS(TypeⅢSecretion System,T3SS)致病岛特征并验证它们在Erwinia属的21个菌株基因组上是否存在。生物信息学分析发现,Ea273基因组不同位点上存在两个新的T3SS致病岛,称为PAI-2和PAI-3,大小分别为32.889kb和21.792kb。经PCR和Southern blot证明Ea273、Ea246、Ea262、Ea528以及Ea6445个菌株基因组存在PAI-2和PAI-3。PAI-3和PAI-2在基因结构和组成上相似,同源性超过70%,PAI-3包含PAI-2所有基因,两者和昆虫内生菌S.glossinidius编码的T3SS的SSR-1致病岛非常相似。 相似文献
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S.V. BEER 《EPPO Bulletin》1979,9(1):13-25
Understanding the disease cycle of fireblight requires knowledge of the sources of inoculum and means of dissemination. In regions where the disease is endemic, hold–over cankers are the most important source of primary inoculum. Dissemination of primary inoculum occurs by rain or by crawling or flying insects. Often, blossoms infested with Erwinia atnylovora (Burrill) Winslow et al. provide secondary inoculum that is disseminated by pollinating insects or by rain. Later in the growing season, secondary inoculum produced in infected tissues may be disseminated by rain or by sucking and biting insects. Relatively rare sources of inoculum and inefficient means of dissemination may be responsible for introducing the pathogen to areas where fireblight has not been found previously. E. amylovora may be carried to new locations in intimate association with host tissues (infected nursery stock), in association with vectors (insects, birds or man), or by wind as “strands” or in airborne water drops. Every effort should be made to prevent introduction of E. amylovora into areas now thought to be free of fireblight. Attempts to eradicate the disease from several new areas in northern Europe have been unsuccessful. Because weather conditions and the host plants present in southern Europe are especially conducive to severe damage from fireblight, plant protection personnel are advised to prepare now for the possible introduction of disease. Personnel should be trained to recognize the disease and plans should be drawn to contain it or to manage host plants to minimize disease losses. 相似文献
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Hungry animals were trained to press a lever for brain stimulation. Different tones were presented concurrently with the stimulation. A second lever delivered food only during critical tone periods. Animals were able to discriminate tones presented concurrently with rewarding intracranial stimulation, and they also interrupted self-stimulation behavior to respond appropriately under other reinforcements. 相似文献
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