Sudden Oak Death

Disease

Critical Threat

Affects: Tanoak (most lethal), coast live oak, California black oak, Shreve oak, and 100+ other species as carriers

Photo: Joseph OBrien / USDA Forest Service (CC-BY-3.0-US (Bugwood))

Identification & Biology

Water mold (Phytophthora ramorum) that causes cankers on oak trunks, leading to rapid death. Spread by rain splash from infected bay laurel leaves. Has killed millions of oaks and tanoaks since 1990s.

Current Status

Established in coastal counties from Big Sur to Humboldt. Expanding. No cure.

States affected:

California

What Homeowners Should Do

Remove bay laurel trees within 30 feet of valued oaks (reduces spore load). Preventive phosphonate trunk injection on high-value oaks. Do not move infected plant material or soil.