Norway Maple bottom branch wilt

[White Barn Farm]

We have a beautiful Norway maple in our yard. It's about 40 years old and has a nice shape.This spring I started noticing that the bottom branches are wilting and that the branch appears like they are dying. The tree looks healthy other than that. I fertilize it every year. I have checked it for insect damage but can't see any. I wondered about too much water but we have very gravely soil. I'll try to get pictures. Any help would be appreciated.
Thanks,Ed