Lichen in maple trees - should I be concerned about the trees health? Can I remove it?
I have three maples on our property - 2 probably 20+ year old japanese and one 6 year old coral bark. I have read that lichen in and of itself is not harmful to the tree but may indicate that the tree is struggling. I am planning on having pruning done next week to remove dead and crossing branches. Should I be applying fertilizer to these trees? If so - what kind and how is this done with larger specimens like these? I really don't love the lichen on there - it is spoiling the look of the coral branches of the coral bark maple! Anything I can do to keep it to a minimum? Can it be brushed off or will that harm the tree bark? Thanks for your help, Colleen
Multnomah County Oregon
Thank you for your questions, Colleen. (1) Lichens will not hurt your trees, unless they are so profuse as to hold water and pose a breaking hazard. They are very valuable in the environment, some able to clean the air; others providing food and habitat for wildlife. Whether your trees are struggling or not would best be assessed by an arborist, but removing the lichen will not help the plants become healthier. You can probably injure the trees more by trying to knock them off, or spray them. You can read about this fascinating life form here: https://herbarium.usu.edu/fun-with-fungi/lichens
(2) If your trees really need supplemental fertilizer, it should be applied in early spring, before growth begins. Here is an Extension article on this topic: https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/fs103.pdf
Fertilization begins at the top of page 2.
Hope these are helpful. Good luck!