Acute oak decline
A new disease condition of oak trees, Acute Oak Decline (AOD), is taking hold in Britain.
Mature oaks, more than 50 years old, are affected and trees are characterised by symptoms of extensive stem bleeding. Both of Britain’s native oak species, pedunculate oak (Quercus robur) and sessile oak (Q. petraea) are affected.
Dark fluid exudes from small cracks on the bark of stems and runs down the tree trunk.
The fluid may dry and cake on tree stems at certain times of the year.
In contrast to chronic oak decline, some of the affected trees die within four to five years of the onset of symptoms. In the early stages of the disease no changes in canopy health are noticed but as trees approach death canopies may be visibly thinner.
An illustrated version of this note is available here