Lichens are unique because they are an organism that grows as a result of a symbiotic relationship between fungus and algae. The fungus grows on the tree and collects moisture, which the algae needs.
In return, the algae can create food from the energy of the sun, which feeds the fungus.
Lichen on tree bark is completely harmless to the tree itself.
They attach to the tree but do not go deep enough to cause damage. Some people find it to be an eye sore and would like to learn how to get rid of it.
One way is to gently scrub the bark of the tree with a soapy solution, being careful not to scrub too hard, as this can damage the bark of the tree, which will open the tree to disease or pests.
Another method to kill tree lichen is to spray the tree with copper-sulfate. Copper-sulfate sprayed on lichens will kill the fungus portion of the organism.
Only use copper-sulfate as a treatment for tree lichen in late spring through early fall. It will not be effective in cool weather.
The best treatment for tree lichens is to change the environment where the tree lichens are growing.
Lichens on trees grow best in cool, partly sunny, moist locations. Thinning out tree branches overhead to allow for more sun and airflow will help.
Also, if you use a sprinkler system, make sure that it does not routinely spray the place where the lichen is growing, as you are essentially “watering” it and helping it to survive. If you would like free consult on potential tree fungi, call Joseph McIlvaine Tree and Lawn at 215-322-8394 or visit us at mcilvainetree.com.