Lichens

I get calls all the time about lichens on trees and the supposed harm they are doing. Lichens are the leafy, grey-green looking growths that appear on the bark of trees. Lichens are an example of a symbiotic relationship between algae and certain fungi and as such are capable of producing their own food. The effect of lichens on a tree are only slightly detrimental owing mostly to their appearance which can be “crusty” looking. These are not parasites like mistletoe but are called epiphytes since they derive their nutrition from the air and not from the plant they grow on. Lichens can indicate a problem with the tree they are growing on. They need sunlight to grow so it may indicate a thin or thinning, unhealthy tree but not because of the lichens. If you still insist on taking them out then spray your tree with copper compounds which are deadly to fungi and algae.