Sudden Oak Death is the common name for a disease fatal to oaks and other tree species. The disease is caused by the pathogen Phytophthora ramorum, a fungus-like organism. The pathogen has reached epidemic levels in several California forests, killing thousands of trees in individual forests. Overall, in coastal California, the pathogen has killed over a million trees, many in densely populated neighborhoods. Oak populations in California and Oregon have been severely affected by Sudden Oak Death. It has also attacked trees in Europe. In Germany and Denmark, it has recently been identified as the disease attacking Rhododendron and Viburnum. Symptoms of the disease include bleeding cankers on the tree’s trunk and the death of foliage. It can, in many cases, result in the death of the tree.
The dangerous effects of Phytophthora ramorum are not, however, limited to trees. The disease also infects many other plant species such as rhododendrons, in which it causes the foliage disease “ramorum dieback.” This disease is non-fatal. Such plants can act as a source of the inoculum for the disease, with the pathogen producing spores that can be transmitted by wind and rainwater.
Sudden Oak Death concerns everyone interested in the preservation of major tree species. Property-owners with oaks and other affected species on their land should be concerned about the safety of their trees in the face of this disease. In Section 12, the TREATMENT section of this website, can be found the options presently available to those who wish to take all precautions to preserve their trees.