Sudden Oak Death
MODERATEPhytophthora ramorum
Overview
A water mold disease that has killed millions of oaks and tanoaks along the Pacific coast since the mid-1990s. It also infects over 100 other plant species that can serve as carriers, including rhododendron and bay laurel.
- Type
- Disease
- Severity
- MODERATE
- Source
- iNaturalist
Symptoms
Dark cankers bleeding reddish-black sap on trunk, rapid canopy browning, bark beetle colonization of weakened trees, leaf spots and shoot dieback on foliar hosts like rhododendron and bay laurel
Affected Species
Geographic Spread
Treatments
Phosphonate Trunk Injection
Preventive application of potassium phosphonate (Agri-Fos) via trunk injection or bark spray on high-value oaks in areas adjacent to known infestations. Does not cure infected trees.
Reduce Bay Laurel Understory
Removal of California bay laurel trees near oaks, as bay laurel is the primary sporulating host that drives the epidemic. Significantly reduces local inoculum and infection risk.
Recommended Products & Tools
Helpful supplies for managing Sudden Oak Death. Always read and follow label directions, and confirm a diagnosis before treating.
Protectant spray for many bacterial and fungal diseases.
For the rare case sealing is advised (e.g., oaks in oak-wilt season).
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Frequently Asked Questions
What is Sudden Oak Death?
A water mold disease that has killed millions of oaks and tanoaks along the Pacific coast since the mid-1990s. It also infects over 100 other plant species that can serve as carriers, including rhododendron and bay laurel.
What are the symptoms of Sudden Oak Death?
Dark cankers bleeding reddish-black sap on trunk, rapid canopy browning, bark beetle colonization of weakened trees, leaf spots and shoot dieback on foliar hosts like rhododendron and bay laurel
Where is Sudden Oak Death currently found?
Sudden Oak Death is currently active in California, Oregon. It has been reported in 2 total states across the United States.
What plants are affected by Sudden Oak Death?
Sudden Oak Death affects Red Oak, Live Oak, Rhododendron. Susceptibility varies by species.
How do I treat Sudden Oak Death?
Treatment options for Sudden Oak Death include: Phosphonate Trunk Injection, Reduce Bay Laurel Understory. Treatment approaches may include chemical, biological, cultural, and mechanical methods depending on the severity and context.
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