WSU Extension

Hortsense

Common Diseases
 
Armillaria root rot 
Botrytis blight (Gray mold) 
Cankers 
Crown gall 
Damping-off 
Dead roots 
Dodder 
Downy mildew 
Dwarf mistletoe 
Galls 
Leaf spots and blights 
Nectria cankers 
Phytophthora root rot 
Powdery mildew 
Pseudomonas bacterial canker 
Root rots 
Rusts 
Sclerotinia white mold 
Sudden oak death 
Tubercularia canker 
Verticillium wilt 
Viruses 



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Caption: Madrone canker
Photo by: R.S. Byther
  
Common Diseases : Cankers
(revision date: 4/30/2013)


Biology
Cankers are localized wounds or necrotic lesions, often sunken beneath the surface of the stem of a woody plant. Cankers can be caused by fungi, bacteria, or winter damage. Determining the cause of the problem is the first step in managing a canker problem. Examine the canker for fruiting bodies of fungal pathogens. Check diagnostic references for the common canker problems on that particular host plant.
Management Options

Non-Chemical Management
  • Plant trees properly and in suitable locations. Protect from rain and frost, if feasible.
  • Burn or cauterize cankers using a hand held propane burner to kill pathogens and lessen disease spread.
  • Give the plants appropriate care. This keeps trees vigorous and helps them to better resist disease.
  • Remove and destroy cankered branches when first noticed. Perform disease management pruning or surgery during dry weather, and especially before fall rains. Sterilize pruning tools between cuts and before use on healthy plant tissues to avoid spreading disease.
Select non-chemical management options as your first choice!

Chemical Management

Determine the cause of the problem. Then refer to the fact sheet for management options specific to that host plant and causal organism.

Images

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Caption: Madrone canker
Photo by: R.S. Byther
Caption: Honey locust Nectria canker
Photo by: R.S. Byther
Caption: Nectria canker fruiting bodies
Photo by: R.S. Byther
Caption: Tubercularia canker fruiting bodies
Photo by: R.S. Byther
Caption: Willow canker
Photo by: R.S. Byther
Caption: Honey locust Nectria canker
Photo by: R.S. Byther
Caption: Birch Botryosphaeria canker
Photo by: R.S. Byther
Caption: European canker on apple
Photo by: R.S. byther