Sudden Oak Death

Stop the Spread of
Sudden Oak Death

photo: Tanoak killed by Sudden Oak Death disease, Big Sur.
photo: Leaf and twig dieback symptoms in tanoak.

Left: Tanoak killed by Sudden Oak Death Disease, Big Sur. Photo credit: Karl Burmeyer, UC Cooperative Extension.    Right: Leaf and twig dieback symptoms in tanoak. Photo credit: California Oak Mortality Task Force.

An aggressive disease called "Sudden Oak Death" (SOD) is killing our native oaks in many areas along the California coast, including Big Sur. Caused by a pathogen called Phytophthora ramorum, it kills tanoak and coast live oak, and also causes leaf spots on California bay laurel and other native and common ornamental species in this area.

The pathogen attacks a tree's bark and vascular system, stopping the flow of nutrients and water throughout the tree. Symptoms vary among tree species, but can include "bleeding" of sap through the bark, cankers, leaf spots and twig dieback. The pathogen appears to kill a tree very quickly (a few months) but it can also weaken it to the point where other destructive tree pests can take hold.

While there is still much to learn about how P. ramorum spreads from place to place, it is known that the pathogen is transported in moist soil and mud. It may also be transported through many commonly gathered plant materials like leaves from the California bay laurel tree. The threat of pathogen movement is greatest in muddy areas and during rainy weather.

Please help slow the spread of Sudden Oak Death and protect our beautiful native oaks by following these practices:

  • Become familiar with the symptoms of P. ramorum.
  • Avoid traveling through areas where trees are displaying symptoms.
  • Watch for signs warning that you are in an infested area. (Note: P. ramorum is spreading rapidly along the Big Sur Coast and not all infested areas are marked.)
  • Stay on established trails.
  • Respect trail closures.
  • Before leaving an infested area, remove soil and mud from your shoes, tires, pet's paws and horses' hooves.
  • Respect all quarantines, including prohibitions on the cutting and transport of firewood and gathering of plant materials.

Warning! Dead trees or trees weakened by Sudden Oak Death have been known to topple suddenly and without warning. Be on the lookout!

To learn more about Sudden Oak Death and its symptoms visit the California Oak Mortality Task Force website at .