Question
I have two Maples in my front yard. One is a Red and the other Green. They recently were trimmed back to allow sunlight to reach my porch and flower bed. Now the heavily exposed areas of bark, from the ground up to the leaf canopy, has turned green. Its like a moss or a mold. I live in a suburban area and the trees are between my sidewalk and street. What exactly would be on the trunks and is there something I can do to clear it up? It is also much more noticeable after a good rain. I dont know how old they are. Could you give me insite please? thank you very much.

Answer
Summer:

The extra light probably stimulated the growth of these organisms--may be lichens (leaf-like growths) or possible moss as you mentioned. You can take a closeup photo and send to me in a followup message and I'll attempt to ID (be sure it is in focus before you hit the "send" button. These things should not harm your tree- but mostly unsightly.  Any chemicals may harm the tree.  If feasible/practical, you might be able to "brush" these off.

Regards
Steve