Join the RHS today and support our charity
Free personalised gardening advice
RHS members get reduced ticket prices
RHS members get free access to RHS Gardens
Reduced prices on RHS Garden courses and workshops
020 3176 5800
Mon – Fri | 9am – 5pm
Make a donation
I have forgotten my password
Keep me signed in
Register for free to receive our newsletters, add comments to blogs/articles and to save content.
See what events are on near you and browse your bookmarked pages.
Don’t miss out - book in advance and save
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
the RHS today and get 12 months for the price of 9
RHS members can get exclusive individual advice from the RHS Gardening Advice team.
Register for the site or sign in to share your experiences on this topic and seek advice from our community of gardeners.
We're a UK charity established to share the best in gardening. We want to enrich everyone's life through plants, and make the UK a greener and more beautiful place.
Join the RHS today and get 12 months for the price of 9