There doesn't seem to be a tree group.

The south side of the three 20 year old trees look green
& healthy and that's the side I see most of the time but today
when I was on the north side I was shocked to see they are
bare of leaves (I guess that's what their called) There are
clusters of seed pods, the bark looks healthy and some
of the remaining leaves look brown. I always thought they
get enough water.

Tomorrow I'll pour some five gallon buckets of liquid
fertilizer around them and see if that helps.

Has anyone had this problem with their trees and can you give
me some pointers on what to do?

On this type of tree can leaves ever grow back?

If they have a disease there are five younger trees in that row
and I hope they don't get whatever it is.