Whitefly and Sooty Mold on Gardenias: Integrated Control

Cause and Effect

Black, rub-off powder on gardenia leaves is sooty mold growing on honeydew from whiteflies. Whiteflies are tiny, white-winged insects on leaf undersides with rapid reproduction (egg to adult in <40 days at 65–75°F).

Persistent Spraying Is Key

Almost any insecticide kills whiteflies, but coverage under leaves is critical. Use insecticidal soap, neem oil, horticultural oil, permethrin, bifenthrin, or lambda-cyhalothrin. Spray upward under leaves for several minutes per plant. Repeat every 7 days for a month. Calendar reminder for summer re-treatment.

Cultural Support

After whiteflies are controlled, sooty mold weathers off or can be washed away. Maintain plant vigor.