WSU Extension


Rhododendron : Physiological leaf spot
(revision date: 4/23/2014)

Rhododendron leaves sometimes develop variously-sized and -shaped spots. These are usually dark purple in color. The exact cause is unknown, but cultural or environmental stress may result in physiological leaf spot. One particularly susceptible variety is the rhododendron Mrs. G.W. Leak. This problem does not usually cause any permanent harm to the plant.
Management Options

Non-Chemical Management
  • Provide proper culture for the plants, especially proper watering and fertilization.
  • Plant less-susceptible varieties in highly visible locations where physiological leaf spot would be an aesthetic problem.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

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