Black Sooty Mold on Crepe Myrtle: Aphid Honeydew Solution

Diagnosis

Black leaves/branches, sticky residue = sooty mold growing on aphid honeydew. Aphids suck sap → excrete sugar-rich honeydew → mold colonizes. Tree bloomed fine = aphids not killing it, but unsightly and weakens growth.

Systemic Treatment (Best for Large Trees)

Bayer Advanced Tree & Shrub Insect Control (imidacloprid)

• Soil drench around trunk.
• Roots absorb → translocates to leaves.
• Aphids feed → die.
• Season-long protection.
• Apply early spring (bud break) for best uptake.

Alternative: Contact Sprays

• Insecticidal soap / horticultural oil (thorough coverage needed).
• Repeat weekly × 3–4.
• Hard on large trees.

Sooty Mold Cleanup

Once aphids controlled, mold weathers off. Can hose off or spray dilute soap solution (1 tsp/gal) + gentle brush.

Prevention

• Monitor for aphids early spring (new growth).
• Encourage lady beetles, lacewings (avoid broad-spectrum sprays).
• Don't over-fertilize with nitrogen (succulent growth attracts aphids).