Disease threatens to fell Britain's historic oak trees

By Cahal Milmo
Saturday 22 October 2011 22:27

The english oak, the quintessential native tree which saved a monarch and defines the British landscape, is under grave threat from a little-understood new disease that forestry experts fear is spreading far more rapidly across the country than previously estimated.

Acute oak decline (AOD), which is thought to be caused by a previously unknown bacteria, causes trees to "bleed" black fluid and kills them within five years. So virulent and lethal is the infection that foresters believe it could devastate the countryside and urban green spaces even more than Dutch elm disease, which has killed 25 million trees in Britain since 1967.

The Forestry Commission has identified 55 sites across southern England, the Midlands and East Anglia which have been infected so far. But woodland groups believe it has already spread to hundreds more locations and accuse the Government of starving scientists of the funds to research the disease, which only became widely recognised in the past two years.

Peter Goodwin of Woodland Heritage, one of a coalition of 10 conservation and business groups asking for £10m over the next five years to find a cure, said: "This is a truly frightening disease. It has the potential to cause the death of oak trees on a massive scale and it seems to be spreading quickly – evidence suggests it has gone way beyond locations identified by the Forestry Commission.

"We're looking at a disease that has the potential to change our landscape even more than Dutch elm disease, and yet nothing is being done. We cannot afford a repetition of what happened then. Hilary Benn, [the Environment Secretary] has known about this for months and yet the scientists trying to find out how the disease works are desperately short of funding."

Experts say that, as well as spreading towards North Wales and threatening the West Country, the disease is beginning to attack the country's ancient oaks, some of which have lived for more than 400 years. It has been found in Staverton Thicks, a woodland near Woodbridge, Suffolk, where some pollarded oaks date back to the 18th century, and Hoddesdon Park Wood, an ancient forest in Hertfordshire.

Mr Goodwin, who recently sold his own oak plantation in Suffolk rather than watch it die after it became infected with the disease, said: "These ancient trees have previously resisted everything that nature could throw at them. It must be a measure of the risk that AOD poses that they are being infected as well."

The infection is not the only ailment to assail the king of British forests. Another disease, sudden oak death, 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.

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, 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.

The effectiveness of AOD in killing oaks is exacerbated by agrilus beetles, which opportunistically attack infected trees and speed their decline by boring deep into the trunk and further weakening them. One particular problem for foresters is that the method of spreading the disease, whether through the air or through animal or human contact, is unknown.

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.

Hilary Allison, the policy director of the Woodland Trust, said: "The impact of the loss of the tree from our countryside and towns would be catastrophic. AOD has the capacity to be a major threat to the UK's oak woods."

The Forestry Commission is expected to announce new advice to forest owners shortly about how to manage the disease while further research takes place. "Our aim is to gain as great an understanding as possible of the condition so that we can formulate guidance on minimising the condition and managing its impact," it said.

An intrinsic part of our culture: the history

Whether it was the thick foliage that sheltered a young Charles II or the familiar leaves that provide the logo for the National Trust, the oak tree is an intrinsic part of British history and culture.

Covering 130,000 hectares of woodland and parks, the oak was the king of the primordial forests that covered the British Isles before human inhabitants discovered its durability as a timber and began planting it widely. It would be used to build thousands of sailing ships to establish Britain's naval power and its empire.

The oak was a sacred tree for the Celts, but its status as a symbol of Englishness was cemented in the Worcestershire countryside in 1651, when a fugitive Charles II was hidden from the New Model Army of Oliver Cromwell at Boscobel Hall. On 6 September the Stuart monarch spent a day sitting in the boughs of a large oak, fortified by beer and cheese as Roundhead soldiers passed beneath looking for him. Most recently, the oak features on the reverse of the 1987 pound coin.

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