Wax Myrtle Turning Black with Sweet Odor: Sooty Mold from Insects

Wax myrtles (Morella cerifera) developing a sweet, honey-like odor and black coating are hosting sooty mold fed by honeydew from sap-sucking insects—likely scale, aphids, or whiteflies.

Confirm the Source

• Check leaf undersides for:
  • Scale: Small, immobile bumps (tan–brown).
  • Aphids: Tiny, soft, green/black clusters on new growth.
  • Whiteflies: Tiny white moths that flutter when disturbed.
• Black mold wipes off; sticky residue beneath.

Best Treatment: Systemic Insecticide

Bayer Advanced Tree & Shrub Insecticide (imidacloprid) – mix per label, pour at base. Plant absorbs it; kills feeding insects in 1–2 weeks. Protects 6–8 months. Apply when soil is moist.

Why This Works

• Targets the root cause (insects), not just the symptom (mold).
• Ants farming honeydew will leave once insects are gone.
• Mold weathers off naturally after insects stop producing honeydew.

Note

Do not use on edible plants. For food crops, use neem oil or insecticidal soap instead.

Native wax myrtles recover well once pests are controlled.