Lichen is a harmless, either gray or greenish organism that often grows on the trunks or branches of trees. Since lichen will grow on almost any stationary object, it is more likely to be found on mature trees than fast-growing young trees that often shed their bark as part of the growth process. This moss-like plant is a combination of an alga and fungus living together and is non-parasitic since it does not invade the tissue of the bark or cause damage to the tree. However, it can be a sign of an unhealthy tree.
Like most fungi, lichen enjoys a moist environment. It is often found on mature and slow growing trees. It can be found in fast growing, younger trees, especially on the trunk, if the tree is continually subjected to water. This can include constant rain or continuous exposure to the water from a sprinkling system. In these cases, lichen growth is a cosmetic issue and it can be controlled by spraying the tree with copper fungicides.
Signs of Distress
When lichen patches appear on trees that also have unusual leaf drop, it can be the first indicator that the trees are unhealthy. Root rot is the most common cause of the plant’s distress. While the copper fungicides will eliminate the lichen, it will not address the underlying issue. There is no treatment or cure for root rot and the best strategy is planting trees and shrubs which are resistant to this disease.
Keep It Green Nursery has an extensive selection of fruit, citrus, shade and ornamental trees that are resistant to root rot and perfect for our climate. Utilizing a copper fungicide should remove the lichen from your trees and keep them looking beautiful.