Question of the Week: May 2, 2019

“What are these growths on my tree’s trunk, and do I need to be concerned?”

Lichens growing on trunks of tree as photographed and posted by Margi J. on my Facebook page this week.

What you’re seeing are lichens. They’re a symbiotic pairing of algae and fungi that coexist to nourish one another. They gain no sustenance from the trees. In fact, they’re the “moss” you’ll see growing on landscaping boulders. People pay extra money to get them when they’re at the stone yard.

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Lichens growing on the trunk of a magnolia.

Having seen lichens for many years, my only concern is that trees typically shed their bark a bit at a time all along. When the bark flakes off, the lichens go with it. However, if you have a tree that is compromised in some way, its trunk and branches won’t be growing larger and its bark won’t be shedding. Therefore, you can get a build-up of the lichens.

Your best bet, if you’re concerned, is to have a certified arborist look into the vigor of your tree. I have tons of lichens on the trunks of my own pecans and live oaks and I’m not the least bit concerned. Rest well. The world has bigger problems!

Posted by Neil Sperry
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