What to check first
Look at the growth without scraping
Lichens can form flat crusts, leafy patches or small branching structures in several colors. Photograph the surface close up and the whole tree from farther away. A green or gray patch alone cannot identify every bark problem, so seek identification if its appearance is uncertain. [1]
Inspect the canopy separately
Compare leaf size, foliage density and new branch growth with earlier seasons or a healthy tree of the same kind nearby. Note dead branches, recent drought, prolonged wet soil or changed drainage. These observations help investigate decline without assuming the visible lichen caused it. [2]
Check nearby surfaces
Similar growth on a rock, fence or old branch supports the possibility of a surface-dwelling organism. Moss may grow nearby too, but it is a different organism with small plantlike shoots. Neither color nor the presence of both establishes a tree disease. [3]
Choose the next step for your plant
Leave confirmed lichen in place
If identification confirms lichen and the tree otherwise appears healthy, leave the bark undisturbed. No removal program is needed. Lichens have their own means of obtaining water and nutrients, so stripping the trunk is not a way to redirect food into the tree. [1]
Investigate a declining tree
If the canopy is deteriorating, take the tree's species, photos and recent site history to local Extension or an arborist. Ask for an assessment of growing conditions and other damage. Correct a confirmed soil, drainage or pest problem rather than buying a lichen treatment. [2]
What to avoid
- Do not scrape, pressure-wash or scrub living bark to remove lichen; damaging bark creates a new problem.
- Do not apply fertilizer or fungicide solely because lichen is visible. Establish what, if anything, is limiting the tree first.
What to watch next
Keep a dated canopy photograph and compare foliage and growth during the next growing period. Increasing branch death or a rapidly thinning crown deserves a separate assessment even if the bark growth has been confirmed as harmless lichen.
Common questions
Does lichen mean the tree is dead?
No. Lichen grows on living trees as well as dead wood and other firm surfaces. Its presence does not establish whether a tree is healthy or dying. Use foliage, branch growth and a tree assessment to answer that question. [1]
Should I remove it for the sake of nearby plants?
Confirmed lichen is not a contagious plant disease requiring eradication. It can occur on many surfaces and provide resources for wildlife. Leaving it on a healthy tree is a reasonable choice without treating neighboring plants. [3]
Sources and review
This guide was prepared with AI assistance and checked against the sources below. It has not been reviewed by a botanist. Conditions and plant responses vary; use the checks above to decide what applies. Read our editorial standards.
- University of Minnesota Extension: Non harmful tree conditions
Lichen forms, self-supporting growth and no need for removal.
- University of New Hampshire Extension: Lichens on apple-tree bark
Thinning canopies can favor lichens; investigate tree stress and avoid scraping bark.
- Illinois Extension: Lichen in the landscape
Lichens differ from moss, colonize many surfaces and have ecological value.