Mysterious Tree Death

So I have noticed that some trees are randomly dying. Here is some kind of pine for an example. I have found no evidence of insect attack and it also does not appear to be environmental either. If it were environmental it seems like more trees would be affected.
I have also noticed that some cherry trees are dying as well. They seem to be covered with some powdery green blotches. From a distance I disregarded the blotches as lichens but upon closer inspection, it appears to be a mold of some sort. I have no idea what it could be though. I knew I missed the forests while I was in North Dakota but being back among them has filled a void. The depth of said void was far more than I knew. It is good to be home!