Rene Schmit | 5/31/2013 12:46:49 AM
The cloudy wet weather in Louisiana provides the ideal climate for various plant organisms such as algae, lichens and mosses to grow profusely on trunks, limbs and twigs of many trees and shrubs in the home landscape. Since all of these primitive plants contain chlorophyll and make their own food, they do not directly injure the plants on which they grow. Some people like the hitchhiking plants because they add a bit of color to shrubbery and trees during the winter. But at times the growth becomes objectionable or unsightly, and then becomes desirable to control it. The presence of algae, lichens and mosses on plants typically indicates that a plant is in poor vigor and growing slowly. Plants exhibiting this should be checked for drainage, soil composition or poor soil fertility problems.
Algae are the simplest of green plants and are present nearly everywhere and almost any place that has sufficient moisture, such as on tree trunks and twigs, shrubs, rocks, bricks, walls and in fresh and salt water. In larger numbers, algae form the scum on ponds and appear on wet areas in the lawn or garden.
Lichens have two components – a fungus and an algae living in association with one another to give the appearance of a single plant. Lichens grow on soil, trunks and branches of trees and on shrubs and on rocks. Like algae, lichens manufacture their own food, occur in several forms and are usually gray-green in color. Some lichens are leaf-like, some resemble a hair-like tuft hanging from the branches and on tree trunks, and others are flat and crusty.
Mosses are green plants somewhat similar to algae except they are larger and have developed stems and leaf-like structures. Mosses also manufacture their own food and grow on soil, tree trunks and branches and on rocks.
Algae, lichens and mosses, although similar in appearance, are controlled in different ways. Algae growth usually means excessive moisture and fertilizer. Removing either one will control the algae. Lichens can be controlled easily by using a copper fungicide but often requires more than one treatment. Mosses, on the other hand, are more difficult to control. Since they usually grow in shady places, the more common control is to remove branches from the trees that shade them.
Rene’ Schmit is the LSU AgCenter County Agent for St. Charles Parish. He can be reached at 985-785-4473.