Monitoring in the UK of a disease which affects oak trees is being stepped up by the Government as it is thought it may pose a serious threat to the oak population.
Acute Oak Decline causes weeping patches on the stems of mature trees and is on the rise in England, particularly in the Midlands and the South East. The "stem bleeding" symptom of the disease sees dark fluid seep from splits in the bark.
Dr Sandra Denham, of the Forestry Commission, said, "This is a serious problem in the UK. So far we've only seen it in England, but because we haven't done any formal surveys we're unsure as to the full extent of the problem. But we do estimate that there are many thousands of trees that are affected."
Dr Denham added, "But because our native oaks are native they have a very broad genetic base and so we're hoping that there will be some trees that will have a natural resistance to this condition."
Scientists believe that a beetle may be responsible for the disease, and are also trying to isolate a bacteria found on dying trees that could be a link to the infection.
Woodland ecologist, Dr Keith Kirby, of The University of Oxford, said, "Acute Oak Decline is a concern because it can lead to the death of even these large old trees that have survived lots of other impacts, and it appears to be spreading. Although Acute Oak Decline may be spreading less slowly than some other pests and diseases, even slow spread is serious when we think in terms of the lifespan of a tree."
Better monitoring of Acute Oak Decline is part of a strategy to protect tree health after the discovery in the UK last year of Chalara fraxinea, which causes ash dieback. Experts are currently putting together a list of the main tree pests and diseases which threaten the UK.
