The Forestry Commission is concerned that a new disease could seriously threaten the native oak trees across Britain. The disease called acute oak decline (AOD) causes black bleeding on the stem of the trees leading to rapid dieback and death within three to five years. It is thought it could potentially be as damaging to oak trees as Dutch elm disease was to elm trees. The Forestry Commission is urging woodland managers to be vigilant regarding their oak trees and to inform visitors and walkers how to stop the spread of the disease from infected trees. Measures include advising the public not to touch infected trees or remove wood from them and to clean walking shoes and bike tyres that have been used in infected areas.