Symptoms of Sudden Oak Death

Pepperwood (CA bay laurel, Umbellaria californica) and tanoak (Notholithocarpus densiflorus) are the are the two local native plant species known to spread the pathogen Phytophthora ramorum.  As such, they are the two most important species to watch for symptoms of SOD. 

The best identification resource for the north coast is the symptom ID introduction by Humboldt County UC Cooperative Extension

The Garbelotto lab at UC Berkeley has put together an ID sheet  showcasing leaf symptoms on both pepperwood and tanoak.

To see symptoms on various other plants that host Phytophthora ramorum please see the hosts and symptoms page and the plant symptom photos at


Phytophthora ramorum causes a leaf blight on pepperwood and does not kill the tree.  Look for dead leaf tips with yellowing behind a black line. 



The disease often causes mortality in tanoak around two years after initial infection, but may take longer.  Signs of infection include black lesions on the twigs, leaf die back originating in the petiole, dead branch tips, and bleeding cankers from the main tree stem.