Dr. Phyto

European ash

Fraxinus excelsior

Diseases & pests on this plant

• ash dieback (Chalara)Hymenoscyphus fraxineus

  Wilting and blackening of leaves and shoots in summer; diamond-shaped dark lesions form on the bark of stems and branches, often centred on a leaf scar or side shoot, girdling and killing the shoot above; the crown thins and dies back progressively over years, with bushy secondary shoots below the dead parts; saplings can be killed in a season. Tiny white fruiting cups appear on last year's fallen leaf stalks.

• emerald ash borerAgrilus planipennisEU-notifiable quarantine organism

  A slender metallic emerald-green beetle; the larvae tunnel S-shaped galleries packed with frass just under the bark of ash, cutting off the tree's sap flow; the canopy thins and dies back from the top, the tree throws out shoots low on the trunk (epicormic growth), the bark splits over the galleries, and D-shaped exit holes appear. Ash trees die within a few years of infestation.

• honey fungus (Armillaria root rot)Armillaria mellea

  Plants decline, leaf out poorly, then whole branches or the whole shrub/tree dies — often suddenly in summer; under the bark at the base and on the roots there is a sheet of white fungal growth that smells strongly of mushroom; flat black "bootlace" rhizomorphs run through the soil; honey-coloured toadstools may appear in clusters at the base in autumn.