AOD May Decimate the Oak Population

Woodland Heritage, a coalition of 10 conservation and business groups, are seeking £10 million over the next five years to find a cure for Acute Oak Decline (AOD), a disease with the potential to change the British landscape even more than Dutch elm disease managed 30-years ago. Both of Britain’s native oak species, pedunculate oak (Quercus robur) and sessile oak (Q. petraea) are affected.

AOD is thought to be caused by a previously unknown bacteria that causes trees to “bleed” black fluid, killing them within five years.

At the moment the disease is spreading to North Wales and is also threatening oaks in the West of England, and is even beginning to attack ancient oaks, some of which have lived for more than 400-years.

AOD is not the only disease that British oaks need help in fighting. Another disease, Sudden Oak Death (SOD), caused by a relative of potato blight, has already been recorded at dozens of locations across the UK and, despite its name, affects more than 100 species of plants and trees. SOD is also killing oak and other species of tree and has had devastating effects on the oak populations in California and Oregon.

But early analysis suggests AOD is far more dangerous, causing multiple oozing lesions in the bark of a tree, before gradually destroying leaf growth and leading to death. It attacks oaks which have lived for 50-years or more.

Scientists at Forest Research, the research arm of the Forestry Commission, the government department responsible for the protection and expansion of Britain’s forests and woodlands, have identified three types of bacteria believed to be the cause of the infection, but the precise mechanism of the disease is not understood, hampering attempts to control its spread.

Oaks are by far the most common deciduous trees in England, accounting for 16 per cent of all woodland – double that of the next most common species, beeches and sycamores.

However, there is no need to panic and put off ideas about building a conservatory or orangery for your home in oak. Many conservatory builders in the UK source their oak from sustainable sources in Eastern Europe, so you have the reassurance that you will not be removing oaks from the UK landscape to have a conservatory built.