New Diseases Threaten Britain’s Iconic Tree
1. A new disease is spreading across the country’s trees more rapidly than forestry experts had previously expected. It is Acute Oak Decline (AOD), which is thought to be caused by previously unknown bacteria. It causes trees to “bleed” black fluid and kills them within 5 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 since 1967. The Forestry Commission has identified 55 sites across southern England, the Midlands, and East Anglia, which have been infected so far. However, woodland groups believe it has already spread to hundreds more locations and they accuse the Government of denying scientists the funds to do research on the disease, which has only become widely recognized in the past 2 years (The Independent (03/05/10).
2. Peter Goodwin of Woodland Heritage, one of a coalition of 10 conservation and business groups asking for £10m over the next 5 years to find a cure, says: “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.” 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 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.
3. Another ailment has struck the king of British forests. Sudden oak death caused by a relative of potato blight, has already been recorded at “dozens of locations across the UK.” It affects more than 100 species of plants and trees. Early analysis suggest that AOD is the more dangerous affliction. It causes multiple oozing lesions in the bark of a tree, before gradually destroying leaf growth and leading to death. It attacks oaks that have lived for 50 years or more. Scientists at Forest Research, the research arm of the Forestry Commission, have identified 3 types of bacteria believed to be the cause of the infection, but the precise mechanism of the disease is not understood, which hampers attempts to control its spread.
4. 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. The method of spreading, whether through the air or through contact with humans or other animals, is another mystery.
5. Oaks are by far the commonest deciduous trees in England, accounting for 16% of all woodland – double that of the next commonest species, beech and sycamore. Hilary Allison, the policy director of the Woodlands Trust says: “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 management of the disease while research continues.
6. The oak tree is an intrinsic part of British History and culture. Now covering 130,000 hectares of woodlands and parks, the oak was the king of primordial forests that covered the British Isles before human inhabitants discovered its durability as timber and began planting it widely. It would have been used to build thousands of sailing ships to establish Britain’s naval power and its empire.