Oak Disease research UK
Oak Disease research UK
Written by jonathan (07/18/13, 15:58:45)
A mystery disease causing Britain's oak trees to "bleed to death" has prompted a £1.1m research effort to identify its cause.
The government-funded project aims to understand the distribution and severity of acute oak decline (AOD), a fast-acting disease that can lead to the death of an oak tree within three to 10 years of infection. AOD, first observed in the 1980s, is affecting several thousand oak trees across East Anglia, the Midlands and south-east England, but scientists do not know what is causing it.
Dr Sandra Denman, lead scientist on the project to identify its cause, said: "AOD is a serious problem for both of Britain's native oak trees. Oak is our most important native broad-leafed tree species and is iconic to Britain."
Dr John Morgan, head of the Forestry Commission's plant health service, said: "We are determined to do everything possible to protect our trees. AOD is a complex condition, and this new Defra funding will enable us to better understand the condition and the number and distribution of trees affected."
At a biosecurity summit last week, the environment secretary, Owen Paterson, called for a united front against tree diseases: "It is clear that it is only by working together that we can do our best to protect our plants and trees," he said.
Denman said the causes of AOD were complex, and two of the bacteria that had been isolated were unique to the diseased trees. Her team also found AOD coincided with the oak jewel beetle, Agrilus biguttatus, being found within the trees. She said: "Thus a key research question is to determine the relationship between the beetle and the bacteria."
Brian Muelaner, an ancient tree adviser at the National Trust, said: "The disease can be seen on affected trees as a black, tarry-like resin bleeding from the tree bark. The tar forms as the tree floods the infected area with sap to make anaerobic conditions to kill the infection."
With a cure yet to be found, there is no plan for dealing with AOD so diseased trees must be left to die naturally over the five to 10 years it takes for AOD to take hold. If the cause can be identified, a plan can be put in place to prevent the disease spreading.
In the meantime, it is hoped that the public can help by using the Forestry Commission's Tree Alert tool to report suspected cases.
Brian Muelaner added: "Thankfully the disease is not affecting the ancient trees, those that are over 600 years old, but if we lose younger trees then we will have a generational gap in the future which affects biostability in the environment."
The independent Tree Health and Plant Biosecurity Expert Taskforce, set up as a result of the discovery in the UK last year of Chalara fraxinea, which causes ash dieback, found AOD to be one of a number of pests and diseases that are an immediate threat to the UK or have the potential to have a severe impact.