ABSTRACT The present study documents the frequent occurrence of the fir pathogen Neonectria neomacrospora in Austria, where it was first confirmed in 2019 on Abies concolor . In field surveys in 2019 and 2024 the pathogen, identified morphologically and through rDNA ITS sequencing, was found scattered across northern Austria, from the federal state of Vorarlberg in the west to Vienna in the east. N. neomacrospora was recorded at 13 localities on young Abies alba trees in forests, at three sites on ornamental Abies concolor trees and on one Abies fraseri tree in an arboretum. While A. concolor and A. fraseri were severely affected, disease intensity varied on A. alba . In forest stands at cool‐moist sites, N. neomacrospora caused substantial twig and top dieback as well as mortality to naturally regenerated, densely growing A. alba saplings, indicating a potential risk for this native fir species. In a wound inoculation experiment on saplings, Austrian N. neomacrospora isolates caused faster external symptoms, more extensive phloem necrosis and higher mortality on A. concolor than on A. alba . Picea abies remained virtually unaffected, questioning its classification as a host tree. In a growth experiment on 2% malt extract agar, the four isolates used in the inoculation experiment presented optimum growth at ~20°C, showed no growth at 30°C and did not survive after 3 weeks at 35°C. This study indicates that N. neomacrospora is an important pathogen on non‐native fir species and A. alba saplings in Austria. However, higher temperatures may limit the pathogen's impact.
Rabl et al. (Fri,) studied this question.