Hibiscus White Substance on Leaves: Powdery Mildew or Mealybugs?

5-Year-Old Hibiscus: White Residue = Two Very Different Problems

Dense white substance on dark green leaves: powdery mildew (fungal) or mealybugs/scale (insects). Treatment differs entirely.

How to Tell

• Powdery mildew: Looks like dusted flour. Wipes off as powder. On leaf surfaces.
• Mealybugs/scale: Raised, bumpy, waxy. Mealybugs = cottony; scale = hard shells. In leaf axils, stems, undersides.

If Powdery Mildew

• Prune affected leaves.
• Improve air circulation.
• Fungicide (sulfur, neem oil, or potassium bicarbonate).
• Don't wet leaves when watering.

If Insects

• Alcohol Q-tip for visible ones.
• Spray alcohol solution (1:5 + soap) thoroughly.
• Repeat in 5–7 days.
• Prune heavily infested branches.

Prevention for Both

• Bright light, good airflow.
• Water at soil level.
• Monthly inspection.