Controlling Lichens

Many homeowners are concerned about lichens growing on the limbs and branches of trees and shrubs.  Lichens are usually gray or greenish gray and grow in different forms.  Some have a feathery, moss-like appearance, while others have a ruffled type of growth, or even a leaf-like form with flat sheets of growth held tightly to the bark or leaves. 

 These unusual creatures often get mistaken for a harmful fungus or algae that kill our beloved plants.  But the truth is that lichens are actually a combination of both an alga and a fungus growing together, each one helping the other.  Since the fungus is unable to produce food through photosynthesis, it is dependent on its algal partner which can produce enough food for both to survive.  In turn, the alga receives water and nutrients from the fungus. 

 Thus, lichens growing on plants are not parasites and do not harm the trees in any way.  They are only using the plant as a home.  In fact, lichens will grow almost anywhere: on soil, rocks, wood fences, brick houses, plants, and on other lichens.  Usually lichens are most prevalent on plants which are unthrifty or declining in health for one reason or another.  As the canopy of the plant becomes sparse, more sunlight is able to reach the inside branches, which makes a perfect location for lichens to grow. 

The best method for controlling lichens is to keep the plants in a good growing condition.  If lichens do occur, even on healthy plants, they may easily be removed by hand during dry conditions. However, since most lichens will not grow in areas with air pollution, homeowners should be glad to see a lichen here or there, as this is a sign that the air is relatively clean!

Printable PDF "Lichens"

These lichens were found living on some of the Crape Myrtles planted outside the Baker County Extension Office.