willow tree problem

tree is about 5 years old, has been growing fine until last few months leaves have turned brown and the lower 1/2 of the tree looks dead with only a few scattered green sprouts has had plenty of water as has been a wet year planted a corkscrew willow 20 yards from this tree and it appears to be fine another standard willow planted last fall 30 yards away is also fine. No damage to tree and the bark is undamaged

Answered

Lunenburg County Virginia about 5 years ago