DISEASE
 
   NAME
     Leaf Gall in Azalea
     Exobasidium vaccinii

Description
An airborne fungus

Symptoms
This fungus is most commonly seen on the leaves but will attack the flowers or seed pods and although this fungus is similar to leaf gall on Camellia, it will not spread to Camellias.  Affected leaves turn light green or white and become deformed, thickened or rubbery and form rosettes at the end of the branches.  The resulting galls may become bloated and during wet weather white spores form on the affected parts.   A simular fungus is (Exobasidium azaleae) that also produces thickened leaves which form white to pinkish galls.

Source and Dispersal
It originates from other infected plants.  Spores are distributed by wind and infected stock.

Favoured Conditions
It prefers warm humid weather and favours new growth on the plants.

Affected Plants
The host plants are primarily cultivars of azaleas such as ‘Hexe’, ‘Advent Bells’ and ‘Phoebus’ but may also affect blueberries and other Rhododenron species. 

Arctostaphylos manzanita is infected by (Exobasidium oxycocci) causing reddish leaves and shoots. (Exobasidium vaccinii-uliginosi) produces leaf galls and witches broom.

Arctostaphylos uva-uris is also infected by this fungus.

Non-chemical Control
Prune and remove infected parts and destroy by burning.  Heavily infested plants may be discarded.

Chemical Control
Preventative spraying of copper oxychloride (fungicide) on new growth. Once symptoms have been identified it is too late to treat the plant in that season.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.