NATIVE OAKS SUSCEPTIBLE TO NEW TREE DISEASE
Two cases of a new pathogen that could seriously affect trees have been found in native English oak (Quercus robur) trees in a wood near Redruth in Cornwall. This is the first discovery of fungal disease caused by this Phytophthora species in native oak trees in Britain.
The pathogen, is related to Phytophthora ramorum, known in the USA as Sudden Oak Death because of the widespread blight it has caused on American oak species. However, until now, native British oaks have proved to be resistant to both pathogens. Since the first discovery of P. ramorum in Britain early in 2002, neither laboratory tests nor painstaking surveys of more than 1500 woodland and forest sites across Britain have established any susceptibility of native oak trees to the deadly fungus.
Although P. ramorum is known to exist in more than a dozen countries throughout Europe, the new Phytophthora is so far thought to be specific to Britain. A major concern is that laboratory tests and observations in the wild indicate that it is more aggressive, and much faster spreading, than P. ramorum. Rhododendron, the main host and source of infection, succumbs in just a few weeks, rather than months.
Diseased Oak
This latest discovery raises fears over the pathogen’s potential impact on Britain’s 200 million oak trees, as well as other native tree species that may now prove to be susceptible.
The Forestry Commission’s Head of Plant Health, Roddie Burgess, said:”Our hope was that P. ramorum, and this more virulent pathogen, would not spread to native species. This new evidence indicates that this is not the case. We need to ensure that the precautions we take to identify and control the spread of this disease are commensurate with this significantly more serious threat.
If anyone suspects the presence of the disease on plants they should contact their local Defra or SEERAD office. If the disease is suspected on trees the contact should be the Forestry Commission. Further information on the two phytophthora is available on the Forestry Commission and Defra websites –
www.forestry.gov.uk and www.defra.gov.uk
