Host: Gary Bachman, Ornamental Horticulture Specialist
Extension offices are getting calls about gray green stuff growing on their plants today on Southern Gardening.
In the winter landscape it’s easy to see defects and other problems; especially strange things growing ON the landscape plants. Concerned homeowners wonder if this moldy looking gray-green stuff is going to kill their plants. The cause for the concern 99 times out of a 100 is an organism called lichen. They are composed of an unlikely combination of a fungus and an algae that survive in a symbiotic relationship. The algae supply the food via photosynthesis and the fungus gathers the water and other needed nutrients. In other words, and I hope you’ll pardon me for this corny pun, the fungus and algae have taken a likin’ to each other.
There are three main types of lichens commonly found in the landscape: flattened and crusty; wavy folds resembling a crumpled sheet; and highly branched balls of fuzzy stuff. Despite the varied appearances they are all lichens. Lichens are commonly observed on trees and shrubs that are struggling and get the blame. Most of the time the lichens were already present before any decline started, but the homeowners think the lichen is responsible. The lichen only grows on the surface of the bark. In fact lichen will grow on any hard surface outdoors from wooden fences to rocks. Just as a piece of metal garden art will mature and gain an aged patina, I personally think that lichen adds that touch of patina to our landscape plants.
I’m horticulturist Gary Bachman for Southern Gardening.