Sudden Oak Death
Phytophthora ramorum
Overview
A devastating oomycete disease affecting oaks and over 100 other plant species. Causes bleeding cankers on oak trunks and foliar blight on many ornamental hosts including rhododendrons and camellias.
Symptoms
Dark, bleeding cankers on oak trunks (no foliar symptoms on oaks). Leaf blight and shoot dieback on foliar hosts (rhododendron, camellia, bay laurel). Dark, water-soaked leaf spots. Rapid decline and death of susceptible oaks.
Environmental Conditions
Humid
Prevention
Avoid moving potentially infected plant material. Clean boots and tools when moving between sites. Plant resistant species. Phosphonate treatments for high-value trees. Monitor for symptoms.
Management
Phosphonate trunk injections or bark sprays for high-value oaks. Remove infected foliar hosts near oaks. Improve air circulation. No cure for infected oaks. Quarantine regulations in affected areas.