Black Sooty Bark on Flowering Peach: Scale Insects and Horticultural Oil Fix

Your 5-year-old flowering peach has black, scrapable bark discoloration. Buds are swelling. You want to know the cause and treatment.

Cause: Honeydew-Producing Insects

The black coating is sooty mold growing on honeydew (sugary excrement) from sap-feeding insects. Top suspects:

• Scale insects (most likely)—immobile bumps on bark and branches
• Whiteflies—clouds of tiny white flies when disturbed
• Aphids—clustered on new growth
• Powdery mildew—white powdery coating turning black

Treatment: Horticultural Oil

Spray thoroughly with lightweight horticultural oil (not cooking oil). The oil smothers scales, aphids, and whiteflies, and the sooty mold will flake off. Repeat 2–3 times, 5–7 days apart.

Critical Timing: NOT During Bloom

Do not spray while flowers are open—oil kills bees, ruins blooms, and prevents pollination. If buds haven't opened, spray now. If blooming, wait until petals drop. Fruit set won't be affected.

This is safe, effective, and preserves your peach crop.