How to Get Rid of Fungus on a Rhododendron's Leaves
- 1). Keep the bed surrounding your rhododendrons clean. Rake up fallen leaves and garden debris as needed. Powdery mildew spores can survive in the old leaf litter and spread to the plant above.
- 2). Trim off badly infested leaves. Check both the top and bottom leaf surfaces for signs of fungus. Leaf removal works best on rhododendrons just beginning to show signs of infection, since you can't remove all the leaves on a badly infected plant.
- 3). Prune rhododendrons yearly to provide air circulation to the interior of the bush. Cut out crossed branches and thin the interior of the shrub. Powdery mildew grows poorly if adequate air circulation is provided.
- 4). Water the shrub at the base and avoid wetting the leaves during irrigation. Overhead watering results in wet foliage and overly damp conditions, which favor the growth and spread of fungal problems.
- 5). Spray the rhododendron with an antifungal spray formulated for use on rhododendrons or azaleas. Follow label application instructions. The spray may not kill off all existing fungus but it typically prevents it from spreading to unaffected parts of the shrub.
