Abstract

The invasive alien pathogenic fungus Hymenoscyphus fraxineus causing ash dieback (ADB) has devastated European ash (Fraxinus excelsior) populations across Europe. Breeding for resistance is the most feasible measure to reduce future losses of ash, and the presence of resistance, albeit at low level, has been demonstrated in numerous genetic trials around Europe. This study is a continuation of the inventories tracking the vitality status of different clones, which started in 2006 at two ash seed orchards in southern Sweden. A new inventory conducted in the summer of 2021 revealed that the ten clones previously identified as the most tolerant to ADB based on periodic surveys from 2006 and onwards still remain the most tolerant, while susceptible clones continued to decline and are completely disappearing from the orchards. Browsing caused mortality in some of the most tolerant clones in one of the orchards during the last assessment period. Despite the animal damage, the stable resistance observed in tolerant clones over a 15 years period forms a solid basis for the continuation of the breeding programme where good candidates are selected for further study.

Keywords

disease type; disease type-shoot disease; fraxinus; host genus-dieback

Published in

Forest Pathology
2022, volume: 52, number: 5, article number: e12773
Publisher: WILEY

Authors' information