Luckily, these are not mold, but lichens! They are not in any way harming the trees. You can watch a video from Penn State about them here: https://extension.psu.edu/do-lichens-cause-harm-to-trees
Thank you for the quick response! It's good to know the Lichens are not causing damage to my tree. As the video suggests, I would not have noticed them if I did not notice how some sections of my tree have become bare. Now onto the second mystery.
Thanks for the previous information, but do you have any strategy for stopping the tree becoming bare?
I am glad to know that lichens are harmless to the tree, so I guess its coincidence that those are the branches that are bare. As you can see in the other pictures these branches are lower to the ground, so maybe available sunlight may be an issue. In one picture, there is something oozing from the tree (pinkish). Typically, I would just trim the leafless branches, but before I committ id ike to get your opinion.
Thanks again for your input. If you need more photos or video, please let me know.