Controlling Scale Insects on Rhododendrons and Azaleas

Diagnosis

White, cottony fuzz at leaf/stem joints on container-grown rhododendrons and azaleas is soft scale. The azalea is heavily infested. Scale honeydew may attract ants or sooty mold.

Effective Treatment

Apply a 2% horticultural oil spray (e.g., SunSpray, Rockland) thoroughly to all surfaces, especially undersides. Repeat in 3–4 weeks and again in fall to suppress overwintering stages. Oil is low-toxicity and smothers all life stages.

Cultural Support

Ensure good air circulation, avoid over-fertilization, and monitor regularly. Container plants may need repotting with fresh media if infestation persists.