What is happening with ash trees in Slovenia region? - Part fives.
Causal agent of the ash dieback disease is an alien invasive fungus Hymenoscyphus fraxineus, which was introduced to Europe from East Asia. The first symptoms of the disease appeared in Europe in the early 1990s and the pathogen quickly spread over the large part of the continent. It represents a serious threat to the common ash (Fraxinus excelsior) and narrow-leaved ash (F. angustifolia) populations. The fungus causes different symptoms and can colonise practically all hose tissues, which results to dieback of crowns and often whole trees. Disease intensity appears to be higher in sites with higher relative air humidity and relatively lower temperatures, and the ash decline is greatly accelerated by secondary pests. Effective measures to control H. fraxineus are not known, and the found resistance of individual ash trees is the solution for the conservation of ash trees in European forests. Thus, this paper summarizes the most important findings of many of the studies conducted so far and provides suggested guidelines for the future management of ash.