Chalara fraxinea (tel. Hymenoscyphus fraxineus)

Ash dieback

Description

This disease causing tree mortality has increasingly been observed in Central European countries on ash trees since 1990s. The first studies revealed the presence of a pathogenic fungus which was described as a new species, Chalara fraxinea, in 2006. Initially, small necrotic spots (without exudate) appear on stems and branches some necrotic lesions are sunken. These necrotic lesions then enlarge resulting in wilting, dieback of branches and particularly in the death of the top of the crown. The disease is often chronic but can be lethal. Ash dieback has been observed not only on forest trees but also in urban areas (parks and gardens) and in nurseries. Sexual stage of the fungus is Hymenoscyphus pseudoalbidus.

Symptom

Small necrotic spots (without exudate) appear on stems and branches some necrotic lesions are sunken. These necrotic lesions then enlarge resulting in wilting, dieback of branches and particularly in the death of the top of the crown.

Tree Species: Ash

Part of a plant- attacked: Tree trunk, Leaf / Needle, Branch

Pest significance: Very harmful

Pest Category: Fungi

Invasive Species: Yes

Present in EU: Yes

Seasonal frequency of occurrence