I think these are lichens, and they are NOT related to moss nor do they cause harm to the tree. I was going to look up how to kill them, but after reading quite a few articles on lichens, I was so fascinated that I could not bring myself to research that part.

My son did a research paper on lichens when he was in elementary school, but I only took the photos so didn't learn from his adventure. I did learn that lichens puff out after rains, so we timed our photo session for maximum size.

You may want to research lichens and then decide how to handle these interesting growths.

those are lichens and they pose no danger to the tree. They only tell you how old the tree is since it takes a while for lichens to grow on anything.

Thank you for the response. I will start to look them up and research further.