This condition can kill a tree in as little as four or five years, and it has been found affecting hundreds of trees across central and south-east England and parts of Wales.
Symptoms include dark fluid bleeding from splits in the bark on tree trunks, and as affected trees approach death there is a notable deterioration of the canopy, or tree tops, and ‘dieback’ of the branches.
Scientists from Forest Research, the scientific research arm of the Forestry Commission, have discovered a previously unknown bacterium which they believe is playing a key role. They are continuing investigations to obtain a better understanding of the disease, how it spreads, and what other factors might be involved. This information will form the basis of appropriate management strategies.
Most (but not all) occurances are south of The Wash and north of the Thames. The map indicates areas where symptomatic trees have been identified from photographic evidence.
Managing Acute Oak Decline - how to recognise the disease, what to do about it, and how to minimise the risk of spreading it.
The guide stresses the importance of monitoring the progress of the disease, of limiting access to infected trees, and of disinfecting boots, vehicle wheels, machinery and equipment to help prevent its spread. If an infected tree is to be used for timber, the guide recommends the bark and sapwood be removed and burnt on site, and the logs cut into planks on site before being removed. Planks can be kiln dried at high temperatures to kill any remaining bacteria. It is unknown whether the disease affects timber quality, so caution is advised when deciding how the timber will be used.
The guide also advises against using acorns from infected sites when planting new oak trees, and explains how to report suspected cases to Forest Research’s Disease Diagnostic & Advisory Service.
The Forestry Commission is urging everyone who looks after oak trees to be vigilant and follow the advice in the guide, which was written by Dr Sandra Denman, Susan Kirk and Dr Joan Webber of Forest Research.