Pest or disease?
Disease complex

Causal agent:
Multiple, including numerous bacteria species and the native oak jewel beetle (Agrilus biguttatus)

Host trees:
Mainly pedunculate oaks and sessile oaks 

Present in the UK?
Yes in England and Wales

Tree Alert required?

Acute oak decline, often referred to as AOD, is a complex disease involving several casual agents.

AOD was discovered in the UK in the late 20th century. It mainly affects pedunculate and sessile oaks but can be found in other oak species. Researchers believe that AOD could occur due to environmental conditions and some studies have also shown it could be a result of historical stress. Research into this disease complex is on-going. 

AOD typically affects older oak trees, but it has also been found in younger trees. It causes dark bleeds down the trunk of the tree. You may find small, D-shaped exit holes of the oak jewel beetle in the bark. In severe cases the tree starts to lose leaves, causing the crown to thin. AOD can be fatal within 4 to 6 years of the symptoms first appearing. For more information on AOD see the resources below.