Sudden Oak Death

Sudden Oak Death

Sudden oak death threatens many of our trees. Learn to spot it and report it.

Sudden Oak Death (SOD) is caused by the P. ramorum water mold pathogen. It is also the cause of the Ramorum Leaf Blight, Ramorum Dieback and Phytophthora Canker Diseases. SOD was first detected in the San Francisco Bay Area in 1993. It spread to a forest in Oregon in 2001. SOD is considered especially dangerous because it affects a wide variety of trees and there is no known cure. The pathogen also infects but does not kill a number of other plants.

More than 75 plant species can either be infected by P. ramorum or facilitate its spread. The host list includes:

  • Bay laurel
  • Bigleaf maple
  • California black oak
  • California honeysuckle
  • California maidenhair fern
  • Camellia – all species, hybrids and cultivars
  • Canyon live oak
  • Coast live oak
  • Coast redwood
  • Douglas fir
  • European ash
  • European beech
  • European yew
  • Evergreen huckleberry
  • Horse chestnut
  • Lilac
  • Madrone
  • Manzanita
  • Mountain laurel – all species, hybrids and cultivars
  • Oak, multiple varieties
  • Pepperwood
  • Red tip photinia
  • Rhododendron (including azalea) – all species, hybrids and cultivars
  • Scotch heather
  • Southern red oak
  • Sweet chestnut
  • Tanoak
  • Toyon
  • Vibrunum – all species, hybrids and cultivars
  • Western maidenhair fern
  • Western starflower
  • Witch hazel
  • Wood rose
  • Nursery stock
  • Wind-blown rain
  • Contaminated irrigation water
  • Infected plants
  • Contaminated soil or potting mix
  • Bark cankers (calluses on woody portions of trees, often seeping black or reddish ooze)
  • Leaf spots    
  • Twig dieback

  • Know the quarantines in your area and learn to leave Hungry Pests behind.    
  • Cooperate with all quarantine restrictions or rules that might be imposed.   
  • Allow authorized agricultural workers access to property to install and inspect insect-monitoring traps.


What's at Risk from the Sudden Oak Death:

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