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Azalea gall attacks certain rhododendrons and azaleas out of doors and is often seen on indoor pot-grown plants of Rhododendron simsii, the popular Indian azalea, obtained from florists.
This is a common disease caused by the fungus Exobasidium japonicum that disfigures, but does not kill, rhododendrons including azaleas. It spreads by airborne spores.
Azalea gall is a very distinctive and curious-looking disease;
There are no fungicides available to amateur gardeners for the control of azalea gall. It is thought that some insect pests may spread the spores of the fungus, and these should be controlled with an insecticide if possible.
The spores of the azalea gall fungus are insect or air-borne, and spread the disease from infected to healthy plants. On germination of the spores the fungus enters the tissues of the host, but can then have a long incubation period so that symptoms may not appear until several months after infection. However, very little detail is known about the life-cycle of the fungus.
A closely-related fungus causes a similar disease on camellias.
Azaleas indoorsCamellia gallDisposing of diseased materialRhododendronRhododendron diseases
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