Lichen on Trees

Posted on September 6, 2018 by Becky Staneruck

By Rob Sculley/Help & Advice

I am often asked about the presence of lichen (and moss to some extent) on trees and shrubs.  Home owners often come to see me reporting that “It’s killing my plants!”

Lichen is an unusual organism composed of a fungus (the body of the lichen) and algae (the part that photosynthesizes food for the fungus), living together in the same body.  You can find it on a variety of places like rocks, fences, or old roots.

Lichen grows in a range of colors, from bright to grayish green, to yellow and orange; growing as a leafy or crusty growth on the trunks or branches of trees and shrubs.

They are not parasitic or harmful to the plant.   Lichen is not attributed to be the cause of poor health on any said plant.

Typically, less vigorous plants and plants with declining growth due to lack of light, poor conditions and health, are susceptible to lichen.  Plants with these conditions tend to have more a wide-spread/open growth habit and if light conditions are increased, make a perfect place for lichen to grow.


What to do about Lichen?

Although there are no products listed to specifically kill lichen on trees and shrubs, dormant spraying with copper can kill the fungal portion of lichen.  Bonide brand Moss Max is also listed for lichen and moss on hard surfaces such as patios, decks, and roofs.

Ultimately, the real question is why is the tree or shrub declining?  We at Shorty’s are always here to help diagnose and discover what the root cause could be.  However, if the tree looks perfectly healthy and the lichen is on its trunk, there is generally no reason to be concerned.  The lichen is just adding character to the bark.

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