WSU Extension

Hortsense

Rhododendron
 
Disease
Armillaria root rot 
Botrytis shoot blight 
Gray blight 
Leaf spot 
Lime-induced chlorosis 
Marginal leaf necrosis 
Physiological leaf spot 
Phytophthora blight 
Phytophthora root rot 
Powdery mildew 
Ramorum leaf and shoot blight (Sudden oak death) 
Rust 
Salt injury 
Sunburn 
Tissue proliferation 
Insect
Aphids 
Azalea bark scale 
Caterpillars 
Lecanium scale 
Rhododendron lace bug 
Rhododendron whitefly 
Root weevils 



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Caption: Sunburn on rhododendron
Photo by: R.S. Byther
  
Rhododendron : Sunburn
(revision date: 6/5/2018)


Biology
Sunscald is caused by exposure of the leaves to bright sunlight during hot weather. Sunscalded leaves on rhododendrons generally have a yellow to brown blotch in the center. Often this blotch has a yellow halo surrounding it. Typically the outside leaves on the southern and southwestern sides of the plant are most severely affected.
Management Options


Non-Chemical Management
  • Choose the right plant for the location. Some rhododendron varieties can tolerate more sun exposure than others.
  • Proper irrigation during hot weather can increase the plant's resistance to sunscald.
  • Provide partial shade with other plantings or move the plant to a less-sunny location.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images

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Caption: Sunburn on rhododendron
Photo by: R.S. Byther
Caption: Sunburn on rhododendron
Photo by: R.S. Byther