Ash dieback, caused by Hymenoscyphus fraxineus, is a serious disease of common and
narrow-leaved ash in Europe. The resistance of individual trees seems to be important for
the maintenance of ash in European forests. In this in situ wound inoculation study, the
susceptibility and differences in resistance to H. fraxineus between Fraxinus excelsior and
F. angustifolia clones were assessed. Neither of the tested clones revealed total resistance
to ash dieback; variety between the tested clones was observed. Differences in necroses
lengths were significant between clones and between two ash species. Longer necroses were
formed in F. angustifolia than in F. excelsior. Some clones exhibiting some resistance to the
pathogen were identified.