Acute oak decline (AOD) has been around for approximately 25 years, it affects our native English oak and sessile oak, particularly those of 50 years or more but it has also been known to affect much younger trees.
Thought to be bacterial although research is being carried out to see if the oak splendour beetle, Agrilus biguttatus (buprestid beetle) contributes to the development and spread of the disease.
A visible dark fluid oozing from cracks in the bark. The splits run lengthways typically between 5 – 10 cm.
The bleeding can stop at certain times of the year leaving dark stains and crusts on the bark.
There may be visible ‘D’ shaped exit holes from the beetles near to the stem bleeds.
The canopy will become visibly thinner although this tends to happen as the trees approaches death.
Some trees do seem capable of recovering from the disease although in severe cases the tree will die within 4-5 years.
In order to import Quercus you must have a plant passport, all imports must be notified to the UK plant health authorities so inspections can be carried out.
For more information on Acute Oak decline please visit Forestry.gov