The first confirmed UK case of a disease already affecting native American oak trees on the west coast of the USA has been found on a single Southern red oak tree in Sussex.
The tree was confirmed as being infected by Phytophthora ramorum, a fungus-like organism which causes a disease which until now had not been witnessed in the UK on established trees, but had been found mainly on rhododendron and viburnum. The tree was growing in an area where P. ramorum had earlier been confirmed causing disease on rhododendrons.
The pathogen is thought to have been present in mainland Europe for about the past ten years, mainly on rhododendron and viburnum. The first UK finding was made on viburnum in February 2002 at a garden centre. Since this time, outbreaks have been found in rhododendron, viburnum and other species. Since 2001, the Government's Forest Research agency and the Central Science Laboratory have been investigating the pathogen to understand what plants are at risk and how it is spread.
Roddie Burgess, Head of the Forestry Commission's Plant Health Service,
said: "While we are concerned that this disease has now been found on oak, this confirmation is an isolated case and we hope it stays this way".
"The infected tree is a Southern red oak, around 100 years old, and native to the USA. It is only occasionally planted here in the UK as a specimen tree. English oak is a white oak and when we checked the white oaks in the vicinity of this outbreak, none of them showed signs of the disease. We shall be continuing to monitor them closely, however."
"Our current research findings suggest that white oaks appear to be less susceptible to this disease than their American cousins. We are not sure how or when the oak became infected, but the pathogen seems to be spread by water and rain splash".
"We are continuing our investigations in order to add to our understanding of this disease."
The Forestry Commission is working closely with the Department for Environment, Food and Rural Affairs (Defra) to co-ordinate work into understanding and managing this disease.
Forestry and Plant Health Minister, Ben Bradshaw said: "While this may only be an isolated case I am very concerned about this development. I have asked the Forestry Commission and Defra to give this the highest priority. Everything possible will be done to prevent the further spread of this disease."
