Fungi associated with necrotic apical parts of Fraxinus excelsior shoots

Stem necrosis was investigated in 2-3-year-old seedlings of European ash Fraxinus excelsior, both self-sown and in plantations within four Forest Divisions in eastern, northern and central Poland. Fungi isolated from the apical parts of shoots showing fresh necroses were identified and the pathogenicity of some of them was determined. Some species were isolated at all four sites; the most consistent members of this group were Cladosporium cladosporioides, Cytospora ambiens, Discula sp., Fusarium lateritium, Phoma sp., Phomopsis scobina and P. controversa. Diplodia mutila was isolated at all the sites, but with variable frequency. It induced necrotic lesions following wound inoculation of stems of 2-month-old and 2-year-old seedlings of F. excelsior in growth chamber and greenhouse conditions.