Individual resistance of Fraxinus angustifolia and F. excelsior clones to Hymenoscyphus fraxineus

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.