HOW TO IDENTIFY IT
Lichen looks like a bubbly, green mat that grows on the trunks of trees. It’s not really a disease. In fact, it is a combination of fungus and algae that rely on each other to survive. This is called a symbiotic relationship. The fungus grows on the tree and collects moisture which the algae need. In return, the algae produces food using the energy from the sun which feeds the fungus.
THE DAMAGE IT CAUSES
Although it might look like a worrying disease, lichen actually doesn’t damage a tree at all; it is completely harmless. Although the lichen has tiny little roots that attach to the tree, they do not go deep enough to harm the tree. The biggest problem with lichen is that you might think that it is ugly but try looking at it with a magnifying glass or taking a very close up photo and you will be surprised how beautiful it actually is.
HOW TO CONTROL IT
If you are absolutely sure that you want to remove the lichen, gently scrub the trunk of the tree with a bucket of soapy water. It should come off fairly easily.
Mum and dad might spray the tree trunk with either lime sulphur or copper-sulfate which will both kill the lichen as well.
Finally, lichen always grows in damp, shady areas so take a look around and see if there are branches overhead blocking the sun. If so, perhaps mum or dad might be able to trim them away to stop the lichen from growing.
Close-up view of lichen.