Lichen on Japanese Maple and New Trees: Harmless Epiphytes, No Treatment Needed

Older Japanese maple and two new trees (Cleveland pear, 'Tamuke' maple) have green mold-like growth on bark. Homeowner asks how to remove safely.

It's Not Mold—It's Lichen

Lichens are symbiotic organisms (fungus + alga/cyanobacterium). They do not parasitize the tree; they use bark as a substrate. Common on slow-growing, sun-exposed bark.

Why They Appear

• Full sun exposure (especially after leaf drop).
• Clean air (lichens are bioindicators of good air quality).
• Slow bark expansion (common on Japanese maples).

No Action Required

• Lichens cause zero harm.
• Removal attempts (scrubbing, chemicals) damage bark more than lichens.
• They may naturally decline as canopy shades trunk.

If You Insist

Copper fungicides (labeled for ball moss) or baking soda spray can reduce lichens but are unnecessary. Leave them be. They're a sign of a healthy environment.

Enjoy the lichens—they add character and indicate clean air.