What's wrong with my Dogwood?

It was in the woods until about 10 years ago when we built the house. We left it in place and it is about 30 yards from the house. It is about 30 feet tall, and I would guess 30-40 years old. Its blooms have become progressively less spectacular over the last several years. I thought it was the every other year thing but it is not. Now the leaves are turning brown at their tips. It is affecting most of the plant, and is worse close to the ground than up top. At the worse, about 20% of the leaf is brown and dead. Any ideas? We had 17 year Cicada’s about 4 years ago, and while it seemed to start weakening then I have a feeling that is just a coincidence.

Probably dogwood anthracnose, Discula destructiva. Google same and have a look.

Unfortunately, the pictures are very similar to what I am seeing. I will have to contact a tree expert, although, from what I have been reading, it seems that the tree will be doomed eventually.