Sudden oak death
This page was published in 2001 - Click here for up-to-date information
Since 1995, a disease known as Sudden oak death (SOD) has been killing large numbers of oak trees along the California coast of the USA.. It is caused by a new species of Phytophthora which has recently been found to be virtually identical to a fungus which is damaging Rhododendron and Viburnum in The Netherlands and Germany.
In Rhododendron, the fungus causes a twig and leaf blight, symptoms of which are most pronounced in summer. Affected twigs develop a brown to black discoloration, usually starting at the tip and moving towards the base. Infected leaves show dark brown blotches. Photographs of these symptoms are available here. In contrast, Viburnum does not show twig blight and infection begins at the stem base and spread upwards, causing the plants to wilt and collapse very quickly. The PHSI and Forestry Commission are currently conducting surveys for the presence of these diseases on nurseries. If you suspect symptoms in your plants, please contact your local PHSI office.
The Forestry Commission is investigating whether the Common oak (Quercus robur) or Sessile oak (Q. petraea) present in this country are susceptible to the fungus. More information about their work is available at www.forestry.gov.uk/planthealth
Page last modified:
10 Oct 2006
Page published: 3 May 2003