Home

Plant Protection - Lichens

Many people are troubled by the appearance of lichens (LY-kens) on their trees and shrubbery.  These blue-green growths with a rubbery texture are a symbiotic (co-dependent) combination of a fungus and an algae.  Lichens do not kill plants as many people believe, but generally live on dead bark and tissues of plants already on the decline.  Lichens also grow on rocks, wooden furniture, walls, and roofs.

If you have just a few lichens, you can hand-pick them if you find their appearance objectionable.  To prevent their spread and establishment in your garden, remove all dead and dying branches and plant parts, and prune back excess growth to encourage air circulation.  If possible, reduce atmospheric moisture and overly shaded conditions, though you may find certain species of lichens on rocks in full sun.

If lichens seem like an unsightly problem for you, they can be controlled somewhat with a copper fungicide.  Bordeaux (bore-DOUGH) mixture is one of these.  Another is the algaecide copper sulfate.  Follow the label directions for general foliar disease control.  You may have to repeat applications if the lichens continue to grow and spread.  Many gardeners consider lichens attractive and actually encourage their growth.

It is also a good idea to check the general health of plants that are colonized by lichens.  Vigorously growing plants that are well pruned and in light, airy situations are rarely seriously troubled by lichens.

WHEN USING ANY CHEMICALS, REMEMBER TO READ AND FOLLOW LABEL DIRECTIONS.