The Q&A Archives: Fungus on azalea

Question: I have 6 or 7 azaleas with white flowers in my west facing yard. The past two years they have not bloomed despite fertilizing and mulching. This year I found two problems: The trunks of several plants have turned almost black with whit spots on them(looks like a fungus of sorts) and young leaves curl up and look like cocoons with white spots. I cut away the curled up leaves and sprayed with an organic fungicide (hydroponic extract of neem oil) which seems to help a little, but is getting expensive. Can I use something else to control what is ailing my plants, or should I dig them up and replant?

Answer: What you describe sounds like leaf gall (Exobasidium species) which is a very common fungal disease. In April and May leaves and buds of infected plants develop distorted growth. Leaves and possibly stems become thickened, curled, fleshy and turn pale green to white. In the later stages of the disease, the galls become covered with a white powdery substance. As the galls age, they turn brown and hard. I've found in my garden that the white flowering cultivars are more susceptible to these fungal disease than the pink or purple flowering azaleas.

This disease rarely does enough damage to require chemical control. If only a few plants are affected, pick and destroy galls. If chemical control is necessary on azaleas, mancozeb, copper salts of fatty acids or triadimefon fungicide sprays can be used according to label directions.

It sounds as though your azaleas are under some stress and moving them to a site with morning sun and afternoon shade might help them recover. I think it's worth a try - otherwise they will continue to decline.

Good luck with your garden!

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