WSU Extension

Hortsense

Azalea
 
Disease
Botrytis petal blight 
Cylindrocladium blight & root rot 
Leaf and flower gall 
Leaf spot 
Lime-induced chlorosis 
Marginal leaf necrosis 
Nematode (stunt) 
Ovulinia petal blight 
Powdery mildew 
Root rot (Phytophthora) 
Insect
Azalea bark scale 
Azalea lace bug 
Azalea leafminer 
Obliquebanded leafroller 
Root weevils 
Spider mites 



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Caption: Rhododendron fungal leaf spot
Photo by: R.S. Byther
  
Azalea : Leaf spot
(revision date: 4/23/2014)


Biology
Leaf spot or leaf scorch on azaleas is caused by a fungus. At first, dark red to brown spots appear on leaves in early summer. Later these spots turn lighter brown, while the leaf turns yellow around them. The fungus can survive the winter on dead leaves or on infected plants in a greenhouse.
Management Options


Non-Chemical Management
  • Avoid overhead watering.
  • Space plantings to allow good air circulation so wet leaves can dry quickly.
  • Rake and destroy all leaves from beneath infected plants.
  • Plant resistant varieties. Your county extension agent or WSU Master Gardeners can make recommendations.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Rhododendron fungal leaf spot
Photo by: R.S. Byther