Green Growth on Maple Trunk: Lichens Again

Heavy green growth on a maple trunk and branches is lichens—the same harmless epiphytes described for mulberry. They indicate good air quality and a thin canopy.

Lichen Refresher

• Symbiosis: fungus + algae/cyanobacteria.
• Self-feeding (photosynthetic), not parasitic.
• Three growth forms: crustose, foliose, fruticose.
• Prefer humid, well-lit bark.

What to Do

Nothing directly. Improve tree health to thicken canopy:

1. Fertilize 10-10-10 at 1 lb per inch trunk diameter.
2. Water deeply in dry spells.
3. Prune for structure and light.

Baking soda spray (0.4 lb/gal) is sometimes used but not recommended—focus on canopy density instead.