Place a similar azalea in the shade and it will be almost lichen free. Many landscape plants also become lichen infested when planted in areas where the soil is too wet for most of the year. Soils with a high water table or that do not percolate well prevent some plants from developing an adequate root system. Sometimes, better maintenance of shrubs is all that is required to reduce lichen populations. Since good plant vigor is the key to reducing these structures, a little fertilizer and some water can do wonders.
Lichens are complex structures made up of a fungus and an alga living together symbiotically.
The alga manufactures the sugars or food through photosynthesis, while the fungus provides the moisture and the structure that houses both organisms. There are many different species of lichens, and they come in various shapes and colors. Along the Gulf Coast, there are three basic forms - crustose, fruticose and foliose which are flat and crusty, scaly or hairy. One of my most difficult challenges has been telling the lichen story in a way that it is believable. Since the cause is usually an environmental condition that leads to a weak plant, a specific spray treatment is only a stopgap measure.