Sudden Oak Death in California
MODERATEDisease
Sudden Oak Death is currently active in California. Watch your susceptible trees closely and act early.
About 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.
Symptoms to watch for
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
Trees at risk in California
Tracking one of these? Add it to My Yard to get alerts when threats go active near you.
Treatment options
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.
As an Amazon Associate, TreeIssues may earn a commission from qualifying purchases made through these links — at no extra cost to you.
Need help with Sudden Oak Death in California?
Connect with ISA Certified Arborists serving California:
Browse all California arborists →Frequently asked questions
Is Sudden Oak Death in California?
Sudden Oak Death is currently active in California. Watch your susceptible trees closely and act early.
What does Sudden Oak Death look like?
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
What trees does Sudden Oak Death affect in California?
It affects Red Oak, Live Oak, Rhododendron. Susceptibility varies by species.
How do I treat Sudden Oak Death?
Options include: Phosphonate Trunk Injection, Reduce Bay Laurel Understory. Confirm the diagnosis before treating, and consider a certified arborist for high-value trees.