WSU Extension


Collar rot (Phytophthora) 
Leaf blight 
Leaf gall 
Leaf spot 
Madrone canker 
Madrone leafminer 
Shield bearer 

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Caption: Madrone canker
Photo by: R.S. Byther
Madrone : Madrone canker
(revision date: 4/28/2014)

Several different fungi can cause canker; they are spread by wind, rain, soil, tools, and equipment. They infect the tree at a wound and kill nearby healthy tissue. Cankers expand through the wood in all directions, and tree sap or dark fluid may ooze from the wound. Cankers eventually cut off nutrient and water flow to branches. Leaves may appear stunted or light green. These sunken, brown water-soaked cankers can appear on branches or trunk. Trees may cease spreading the disease by producing callus tissue to trap the fungus. If the expanding canker is controlled early enough, the tree usually survives. However, the fungus may grow faster than the callus, or the tree may not respond with a callus, resulting in serious damage.
Management Options

Non-Chemical Management
  • Prune off dead twigs and branches at least four inches below the canker, and destroy them. Cankers on larger branches should be excised with a knife and chisel. Remove all discolored bark and wood plus a 1-inch buffer zone of healthy wood around the wound. After each cut, sterilize the knife and chisel with rubbing alcohol. Clean the wound with alcohol.
  • Avoid wounding trees with tools and power equipment.
Select non-chemical management options as your first choice!

Chemical Management

None recommended


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Caption: Madrone canker
Photo by: R.S. Byther
Caption: Dieback from madrone canker
Photo by: R.S. Byther