NATIVE RANGE: North America

FIRST FINDING IN SLOVENIA: 2005

PATHWAYS:on sawing tools, dispersion by wind and insects

POSSIBLE TO FIND: yearround

DESCRIPTION: Symptoms of this diseases include brown lesions on leaves and leaf-petioles, which are the entry points of the fungi. Later, the fungus infects bark and causes lesions and dieback of shoots. Oval lesions ap-pear on the bark of the trunk, which quickly increase in size. Sometimes the tree does not die back but a canker is formed at the wound. Trees are often heavily infected and many branches die back but, at the same time, the tree also forms new shoots.

HOST PLANTS: Common ash (Fraxinus excelsior) and nar-row-leaved ash (F. angustifolia), are particularly suscepti-ble, while manna ash (F. ornus) is unaffected.

STATUS: Widespread throughout Europe. In Slovenia, found throughout the country. Most reported from the surroundings of Ljubljana, Rogaška slatina and Murska sobota. 

SIMILAR SPECIES: Dieback of ash trees may also be caused by honey fungi (Armillaria spp.), which cause armillaria root disease. Weakened and dying trees are often attacked by ash bark beetles, for example Leperesinus fraxini.

SOURCE: Field Guide to Invasive Alien Species in European Forests