University of Maryland Extension

Azalea - Exobasidium Gall - Shrubs

swollen puffy galls

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Exobasidium spp.
While very noticeable, Exobasidium leaf and flower gall will not threaten the health of the plant. This problem is more common during cool and wet spring weather. The first symptoms are swollen or puffy portions on newly expanding leaves, shoots, buds or flowers. These areas turn into galls that range in color from green, silvery white, to pink or red depending on the part of the plant infected. As these galls age, they develop a white surface growth which consists of a layer of reproductive spores. Eventually, the infected plant part will turn brown and shrivel up into hard galls.

Control: Fungicide sprays are not effective for the control of this disease. Prevention strategies involve hand picking the galls off before they develop the white sporulating surfaces. This will reduce the incidence of disease next season.


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