WSU Extension

Hortsense

Caption: Rhododendron gray blight
Photo by: R.S. Byther
  
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Rhododendron : Gray blight
(revision date: 4/23/2014)


Biology
Gray blight is a fungal infection of the leaves. It usually becomes established after an injury to the leaf, such as sunscald, frost damage, or some mechanical injury. White spots or blotches with dark margins can be found on the leaf surface. On cut leaves, the infection may spread from the edge of the wound into the leaf tissue.
Management Options

Non-Chemical Management
  • Place plants to reduce injury from sunscald, frost, etc.
  • Infection spreads quickly between cuttings. Do not propagate diseased plants.
  • Prune diseased plants last. Disinfect tools often to avoid infecting healthy plants.
Select non-chemical management options as your first choice!

Chemical Management


None recommended

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Caption: Rhododendron gray blight
Photo by: R.S. Byther