Thoughts on how to treat fruit tree disease!

Hello to everyone! I’m looking for some help treating a disease or fungus on my fruit trees. I have an old neighbor who told me to strain mother’s apple cider vinegar and put it in a new pump up sprayer and liberally spray the trees. I did this on one of my trees many times for an experiment. No results could be seen. Also, I’m located in eastern Tennessee. It’s light gray and scaley, looks like lichen. But the limbs it’s on we’re dead or dying. I just finished pruning today and rid the tree of the dead/dying limbs.
The two trees have lichen all over them but something is killing the tree where it is the heaviest. We bought the property this year and no pruning had been done in around 8 to 12 years from what I was told. No sunlight was able to reach the trunk before I pruned. I'm hoping this will help. We live in the heart of the smokey mountains in eastern tennesse, so we have a heavy dew every morning from may till September. The entire orchard is planted on the north slope of a gentle hill. So drainage is optimal.
Thanks

Yes a foliar spray made from compost tea/EM/kefir/kombocha/etc can work wonders. Maybe once every 4-8weeks. You can also spray the ground under the tree too.

Can you get a closeup picture?