Sudden Oak Death appears to kill trees by girdling the main stem or trunk. Therefore, the number and severity of cankers on the trunk is considered an indication of how serious the infection is and whether it is likely the tree will die.

Why do oak trees suddenly die?

Sudden oak death is a disease of oak trees caused by an invasive plant pathogen, Phytophthora ramorum. It currently occurs in coastal California counties from Monterey to Humboldt and in a small portion of southwest Oregon. It is estimated to have killed more than 1 million oak and tanoak trees during the last decade.

How do you fix Sudden Oak Death?

While there is no cure for Sudden Oak Death or other P. ramorum-associated diseases, there are preventive measures that may protect plants. The publication “Protecting Trees from Sudden Oak Death Before Infection” provides helpful treatment information for areas not currently infested but at risk.