Ash dieback: pathogen spread and diurnal patterns of ascospore dispersal, with special emphasis on Norway.

摘要: Dieback of European ash (Fraxinus excelsior), caused by the ascomycete Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea), started around 1992 in Poland and has since then spread over large geographical areas. By November 2010, disease had been recorded 22 countries. The gradual expansion high intensity dieback epidemic Europe may suggest that H. is an invasive alien organism. In Norway, was first reported spring 2008, a survey early summer same year revealed parts southern eastern regions country. distance from southernmost to northernmost infected stands was, at time, about 400 km. Some old necrotic lesions were also observed, indicating pathogen likely have present Norway least 2006. 2009, spore sampler installed diseased stand As, South-Eastern Norway. Sampling late July continued until September. Large numbers ascospores resembling those with maximum number spores occurring end mid-August. deposition occurred mainly between 6 8 a.m. Ascospores are most be primary source initiating host infections responsible for rapid recent Europe.