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: Pansy Rhizoctonia root rot
Photo by: R.S. Byther
  
Common Diseases : Root rots
(revision date: 4/30/2013)


Biology
Many different fungi that infect root tissues cause similar symptoms: off-color foliage, stunting, wilting, and death. Laboratory isolation and microscopic examination are needed for specific diagnosis. Cylindrocladium, Fusarium, Rhizoctonia, and Pythium are common fungal root rot pathogens.
Management Options

Non-Chemical Management
  • Correct drainage if water puddles near plants.
  • Plant only in deep, well-drained soil.
  • Avoid planting susceptible plants into soil with a history of root rot problems
  • Remove and destroy infected plant materials including roots when feasible to prevent spread of disease.
  • Do not replant in infested potting soil. Clean pots and containers prior to reuse.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Pansy Rhizoctonia root rot
Photo by: R.S. Byther
Caption: Phytophthora root rot on cedar
Photo by: R.S. Byther
Caption: Phytophthora root rot infecting trunk
Photo by: R.S. Byther
Caption: Cylindrocladium root rot
Photo by: R.S. Byther
Caption: Dieback on creeping hemlock due to Phytophthora root rot
Photo by: R.S. Byther