Crown decline (dibeack of branches and parts of the crown) of oaks, associated with characteristic fruiting bodies at the stem base: fruiting bodies mushroom-like (cap and stipe), mostly in fascicles; cap brown to flesh-coloured and spotted, circular, ripe flat, often compressed laterally, up to 8cm in diametre; gills wide, grey to flesh-coloured, spotted, attached to the stipe in form of a ring; stipe often flattened, up to 20cm in length and up to 2cm thick, at the basis extended root-like (spindle-shaped), tough; in the stem white rot of heart- and sapwood, reddish; rot of coarse roots typically orange-red, for a long time limited to the lower half of the root, later on affecting the whole root (cross section).
Affected tree species
Spindle shank is regarded as a primary parasite of various oak species and rarely European beech initially causing limited damage to roots: Following extreme drought periods, especially if these happen repeatedly several times,the pathogen is able to destroy first the vertical roots and by and by the whole root system. As a consequence, crowns get thin and dieback of branches starts. The phenomenon most common in oak stands on sandy soils above rubble: especially alkaline mineral soils below 30cm are favoured by the pathogen. Among the oaks, red oak (Quercus rubra)is most suceptible, followed by pedunculate oak (Quercus robur) and finally sessile oak (Quercus petraea). The rotting process is rather slow, following drought stress up to 30 years may pass until crown symptoms appear.
Curative measures a precise identification can be based on the characteristic fruiting bodies, for tracking the responsible stress period an analysis of the radial increment (stem discs) is recommended. Curative measures are hardly effective. A preventive measure is the careful selection of sites with slightly acid to moderately alkaline soils and a balanced water regime, especially regarding the actual climate change.
Gymnopus fusipes: declining redoak stand
Gymnopus fusipes: thrown redoak with totally destroyed root system
Gymnopus fusipes: fruiting body at the stem base of a declining redoakredoak stand