Question

growth imagag   I am wondering if you might help me identify what a green flaky growth on a swingset is and how we might safely remove it. We have been offered this playset for our children but the flakes, which can be scratched off worry me. Is it is a mold or other microbe that is hazardous?

I have enclosed some pictures, which are close ups of 2 different areas of the playset. I believe the wood of the playset is a redwood. The set is located in long island and sits below what I believe is a maple tree. How can the green growth be safely removed, should any safety equipment be used (respirator, other?).

Thank you for your kind attention.

Stephanie

Answer
These are lichens. Lichens are an example of a symbiotic relationship between algae and certain fungi. They are capable of producing their own food. The algae associated with the fungus is a green or blue-green alga. There are three forms of lichens based on growth patterns. Crustose are species that are closely pressed against the surface of the limb or trunk of dead or live trees. Foliose forms are leaf like or prostrate but are also tightly attached to the tree. Fruticose forms are bush like, erect or hanging. This is the crustose lichen.  Lichens are more than a cosmetic issue on many kinds of materials. Lichen do not have roots like most other plants and it can grow without soil. In moist or damp climates lichen flourish.

They are not a hazard to kids or animals. The flakes are just like the leaves of trees and as they lichen grows some of the "leafy" structure break off. But his is nor a problem.    

You can pressure wash the wood and remove the lichens. Then spray the areas with a clorax and water mixture to seal the wood from reinfection. After pressure washing consider treating the wood with wood preservatives or sealers. This will lower the moisture content of thew wood and the lichens will not grow.

Or you can do nothing, the lichens will not harm anyone if nothing is done. But over time the wood will not be very attractive.