ASH DIEBACK MONITORING IN LOWER AUSTRIA

Ash dieback causes damage and mortality of Fraxinus excelsior (common ash) and Fraxinus
angustifolia (narrow-leaved ash) in Europe. In Austria, the first symptoms of the disease
caused by the fungus Hymenoscyphus fraxineus (anamorph Chalara fraxinea) were
recorded in 2005. To study the development and etiology, 14 permanent monitoring plots
were installed in various parts of Lower Austria and continuously monitored almost every year
since. Twenty mature ash trees per plot were assessed between July and August. The
affected crown volume was visually estimated on a 5 % scale. In 2016 the mean crown
dieback intensity of the remaining 248 trees was compared to their first assessment in 2008
showing an increase from 11% to 29%. Mean damage of the least affected plots also
increased from 1% in 2008 to 11% in 2016.The most affected plot in 2008 remained the most
severely damaged plot in 2016 with a mean value increase from 34 % to 71 %. Overall,
mortality was low with 4 % and observed in five out of the 14 plots. Work is in progress to relate
the long-term observation of ash dieback to climatic data.