Hymenoscyphus pseudoalbidus, the causal agent of European ash dieback

摘要: Summary The ascomycete Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea) causes a lethal disease known as ash dieback on Fraxinus excelsior and angustifolia in Europe. The pathogen was probably introduced from East Asia the emerged Poland early 1990s; subsequent epidemic is spreading to entire native distribution range of host trees. This profile represents comprehensive review state research discovery points out knowledge gaps needs. Taxonomy Members genus (Helotiales, Leotiomycetidae, Leotiomycetes, Ascomycota) are small discomycetes which form their ascomata dead plant material. A phylogeny based internal transcribed spacers (ITSs) rDNA indicated avirulent albidus, species Europe, closest relative H. pseudoalbidus. Symptoms Hymenoscyphus necrotic lesions leaves, twigs stems, eventually leading wilting girdled shoots. Bark characterized by typical dark- cinnamon-brown discoloration. Life cycle Hymenoscyphus heterothallic reproduces sexually petioles litter once year. Ascospores wind dispersed infect leaves during summer. asexual spores only serve spermatia. Tools techniques The most important techniques for fungal handling, such detection, isolation, culturing, storage, crossing ascocarp production, briefly described. Management Once established, management hardly possible. occurrence fraction partially tolerant trees constitutes hope resistance breeding future. Healthy-looking should be preserved.