This afternoon I stopped in at a nursery to pick up some compost for a container gardening project we have with a new fifth grade garden club. As I was checking out I had one eye on the pugs that were eyeing my ankle and the other on this lady who came up on me too fast. Even though we were outside and I had on my mask, she should be respectful of the social distancing. After completing the transaction, I went to load the compost. Just as I began to back away, here comes that same lady waving me down. Do I lock the door? Do I pretend that I do not see her? I did neither, because I knew exactly why she was chasing me; the owner had told her who I am.
As she began to tell me about having an issue, I knew exactly what she was talking about before she took out her phone to show me her image search. We concluded that this white flakey stuff, as she described it, is actually called Lichens. I told her that she would not believe the number of calls or visits I receive on this very subject. The response is always the same. What is it, because it is killing my tree or shrub? Her next response was that it blew in from those 2018 storms. If you are wondering, no that is not true at all.
Lichens are unusual plants composed of a fungus and an alga living together in the same body; the branches or trunk of trees and shrubs become covered with green to gray-green leafy or crusty growth. Lichens are very harmless and are a good physical indicator that your tree or shrub is in poor health. Lichens never attacks or grows on healthy trees.
Lichens attack poor-vigor plants because as the plant declines, the number and size of the leaves decrease. This allows more sunlight to get to the branches and trunk thus allowing lichens to colonize the trunk and branches.
It can be rubbed off the tree but will reappear if the actual problem is not identified and corrected. There is No chemical control for lichens because none is needed. If the plant begins to thrive again, then the leaves will increase in size and number therefore allowing less sunlight to get to the branches and trunk for the plant. Over time, the lichens should disappear.
I told her that usually the decline happens over several years before you even notice that there is something wrong. Naturally, she asked what is wrong. If the problem is not immediately obvious such as a disease or insect damage where you see dead or dying branches, you have to start playing tree detective.
Things such as fertility, soil drainage, boring insects, soil compaction, water as well as mechanical damage are issues that, if not properly corrected or prevented, contribute a lot to the failing health of your trees and shrubs. Start here to find answers.
I encourage everyone to take some time and play tree detective. The earlier something is identified, the easier it will be to control.
Source: The Truth about Slime Molds, Spanish Moss, Lichens and Mistletoe https://secure.caes.uga.edu/extension/publications/files/pdf/B%20999_3.PDF