TAILIEUCHUNG - Báo cáo lâm nghiệp: " Consequences of environmental stress predisposition to pathogens"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài:" Consequences of environmental stress predisposition to pathogens. | Ann Sci For 1996 53 359-368 Elsevier INRA 359 Review article Consequences of environmental stress on oak predisposition to pathogens PM Wargo USDA Forest Service Northeastern Center for Forest Health Research 51 Mill Pond Road Hamden CT 06514 USA Received 18 November 1994 accepted 26 July 1995 Summary Stress alone if severe and prolonged can result in tree mortality. However stress events usually are neither severe nor frequent enough to cause mortality directly. Mortality of stressed trees results usually from lethal attacks by opportunistic pathogenic organisms that successfully invade and colonize stress-weakened trees. Oak trees are predisposed to these organisms by defoliation primarily from insects but also by fungi and late spring frosts and by drought. There is some evidence that injury from extreme winter temperature fluctuations also can act as a predisposing stress. Stress causes physical physiological and chemical changes that reduce energy available for trees to defend themselves provide energy to pathogens for rapid growth or make the tree more attractive to organisms that through multiple attacks overwhelm the ability of a tree to defend itself from attack. Fungal organisms such as Armillaria spp in the root system Hypoxylon spp on the bole and a number of fungi that invade branch systems and insect borers such as Agrilus spp take advantage of changes induced by stress and successfully attack and kill trees. These organisms may be secondary in the sequence of events but are of primary importance in causing mortality. decline stress secondary pathogen Quercus Resume Consequences de contraintes de I environnement sur le chêne predisposition aux pathogènes. Un stress seul s il est suffisamment intense et prolonge peut induire la mort d un arbre. Cependant dans la plupart des cas les périodes de contraintes ne sont ni assez sévères ni assez frequentes pour causer directement une mortalité. Cette dernière résulte généralement d attaques létales par des .

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