Acute oak decline
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?
Yes
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 mature Pedunculate and Sessile oaks but can be found in other oak species. Trees affected by AOD are weakened by unfavourable environmental conditions, allowing colonisation of trees by beetles such as the native oak jewel beetle and necrotising bacteria.
Symptomatic trees have dark bleeds that seep from bark cracks and occasionally, small, ‘D’-shaped exit holes made by emerging adult Oak jewel beetles. In severe cases the tree starts to lose leaves, causing the crown to thin. Ultimately, AOD results in the disruption of essential water and nutrient transport systems, which may lead to death within four to six years.
Research investigating AOD is on-going, with understanding of the complex interactions between the environment, necrotising bacteria and oak jewel beetle improving each year.
For more information on Acute oak decline, see the resources below.
