Rhododendron pachysanthum · Shrub
Vine weevil: Apply biological nematodes in autumn or use systemic insecticides in early spring.
Rhododendron budworm: Prune out affected shoots or apply insecticide when larvae are active in spring.
Powdery mildew: Improve air circulation and spray with a fungicide containing myclobutanil.
Phytophthora root rot: Ensure well-drained acid soil and avoid overwatering; remove severely affected plants.
Algae on leaves: Improve air circulation and light levels; wash leaves with water if unsightly.