Plant Pathology Infobytes

April 14, 1998
Azalea Leaf Gall - Now's the Prime Time for Control

Now's the time to control azalea leaf gall! This fungus disease, which shows up not too long after bloom, has a way of increasing in severity from season-to-season. Leaf gall reduces the ability of azaleas to produce flowers the following spring, since heavily diseased plants lose many of their leaves needed for food manufacture.

What does leaf gall look like? Infected leaves become fleshy and severely distorted. As the galls form, affected parts may become whitish or light green. Sometimes a fleshy rosette of leaves appears at the tip of a branch, or a gall becomes bladder-like as it decays and dries out.

Azaleas are most susceptible to leaf gall when young leaves appear, and like flower blight, is most severe following periods of rainy weather. Infection cycles occur as long as young leaves are present on plants.

What should home landscapers do about this problem? The best control measure is to remove the galls when they are first noticed. This can be done easily when there are only a few galls present. If the galls are not removed from plants, chances are the disease will become more severe from one year to the next. The galls should be destroyed and not discarded in the vicinity of the plants.

There may be situations where gall removal is not practical. In such cases a fungicide spray program is advisable for the control of this disease. Spray the plants once before the new leaves unfurl with captan or a fungicide containing Bayleton. Apply at 10 to 14-day intervals during the spring as long as young leaves are present.

If you need further information about azalea diseases, please feel free to drop by the County Extension Office.


Written by the late Dr. Frank Killebrew

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