I have a 5 year old elm tree and a 3 year old kornus cousa dogwood tree. They both have almost moss like spots on the lower bark. They are grey to white in color. They both haven't grown much. The dogwood has wilting leaves with burnlike edges. It does not look like the common dogwood disease. The dogwood only had about 10 flowers this season. We don't have the best soil but I don't know what to add. I also don't know if these spots are causing the problems on the dogwood or if it is unrelated or not even a problem at all.
Any help would be appreciated.