This disease attacks newly expanding leaves, usually in the spring and fall months when the weather is cool and rainy.
Mature leaves are resistant to infections.
Prune only in late winter before bud-break. Summer pruning encourages flushes of new growth which are susceptible to attack. Space plants far enough apart to encourage rapid drying of the foliage after a rainfall, and avoid wetting the leaves when watering since the fungus is spread by splashing water. Photinia produces several growth flushes a season, so expect to make regular fungicide applications.