Lichens

What are they?           

Many people ask me about the green-gray spots on their tree.  As you can see from the picture, they can cover a tree trunk and branches, no matter how young or old the tree is.  Lichens are a combined fungus and algae.  They will grow on trees, rocks and anywhere it can get a sufficient amount of nutrients, water and sunlight.  Lichens don’t hurt trees in anyway, but some people don’t like how they look. 

Why are they on my tree? 

Trees and shrubs develop lichens for a few different reasons. In areas of the country where there is ample humidity, and trees have a small canopy to shade the trunk, it provides a great place for a lichen to live.  Lichens can be spread by several vectors, and those include wind, water, and insects.  

How do I take care of them? 

To reduce the lichens off your tree or shrub there are several things you can do.  A healthy tree will have a sufficient canopy that will suppress the growth of lichens due to a lack of sunlight.  Applications can be used but need to be made every 7-10 days to adequately cover the tree until the leaves fully develop.  Also, a solution of bleach is a home remedy that can affect their growth.