Taking a lichen to your tree

Steve Borel, LSU AgCenter
Example of tree lichen.

Have you ever noticed a moss like structure growing on your plants branches?

They are not related to moss or any other plant for that matter. They are lichens. Lichens are often found growing on rocks, windowpanes, and yes your plants.

While harmless, the presence of lichens could indicate something is wrong with a plant or tree. Lichens are not pathogens, meaning they don't cause disease in plants. Instead, lichens are a perennial organism consisting of a fungus and a green or bluegreen alga.

The two organisms have a symbiotic relationship. The fungus receives food from the alga through photosynthesis, and the alga obtains water, minerals and protection from the fungus.

When a tree or shrub begins to decline, its leaf canopy thins and allows sunlight to enter and support lichen growth.

If overall plant health is improved, a dense, vibrant leaf canopy should inhibit sunlight available for lichen growth and ultimately shade them out. If you see lichens growing on trees or shrubs in your landscape, then something is causing your plants to grow slowly and decline — plant competition, drought stress, root stress, overwatering, soil compaction, poor nutrition or improper soil pH.

Remove what’s stressing your trees or shrub and you should notice an improvement in the health of the plant.