Black Mold & Scale on Majesty Palms: Treat the Insects, The Mold Will Vanish

Two outdoor majesty palms have black mold; an indoor palm has scaly bumps. Soapy water and plant oil didn't work. What to do?

Sooty Mold Is a Symptom, Not the Cause

The black mold is sooty mold—a fungus growing on honeydew excreted by sap-feeding insects (scale, aphids, mites). Eliminate the insects, and the mold starves and weathers away.

Scale Treatment That Works

1. Swab scale with isopropyl alcohol on frond undersides; let sit overnight.
2. Next morning, hose off dead scale and alcohol residue.
3. Repeat if needed. Alcohol penetrates the waxy scale cover better than oil/soap alone.

Cleaning Up the Mold

Once insects are gone, sooty mold will fade. Speed it up by gently sponging fronds, then rinsing. No fungicide needed.