Black Deck Stains from Maple Tree: Fix the Aphids, Not Just the Deck

Root Cause

The "lycenium/mycelium scale" on your deck is sooty mold fed by honeydew from aphids or scale insects on the nearby maple.

Two-Pronged Solution

1. Treat the Tree (Source Control)

Apply Bayer Advanced Tree & Shrub Insect Control (imidacloprid) as a soil drench now and again early spring. Systemic action kills sap-feeders, stopping honeydew production.

2. Clean the Deck

1. Low-pressure wash (≤1500 psi, wide fan tip) to remove mold without damaging wood.
2. Bleach rinse: 6 oz bleach/gallon water to kill residual fungi.
3. Seal: Apply quality deck sealer (consult paint store) to slow future staining.

Why This Order Matters

Cleaning without treating the tree guarantees rapid re-staining. Treat the tree first; the deck stays clean longer.