Something is killing My Weeping Willow Trees , they start looking stressed then die.  Large areas of Bark will either pop off or can easily be pulled off almost like something is underneath eating it. I know it is not a garden plant but sometimes I plant things just to look at. So far I lost 3 five year old Trees and My 6 year old Tree will be dead next Year if I don't stop this. Anyone familiar with this problem ?  thanks , Stan.

What kind of shape are the leaves in? Have you noticed the bark begins to flake and then the leaves die or vice versa? Have soil conditions changed to your knowledge? Are you able to post pictures?

Also, how old are your trees? They're short-lived trees living no more than 15-20 years per the stuff I've read.

The bark begins to peal then the Leaves slowly fall and then they die.  They looked great untill last Year then they started to look stressed then this Year 3 died and the 4th will be dead next year if I don't do something. Ground hasn't changed any and they had plenty of water.  These are young Trees 6 years and younger.

Is this the first year they've began to die? We had an unusually harsh winter up our way that has taken many trees and perennials. Even of you just noticed the bark peeling now, this is something that could have been going on since the beginning of the year. Do you notice any heavy insect traffic on the tree or fungus? I would thoroughly investigate the trees that are already dead. Peel off the rest of the bark towards the base and in strategic areas, take a few cross sections to see if the trunk itself was healthy. Hollow, rotting spaces on the inside are not uncommon.

Think of any other changes that may have been made around the trees. Are they getting more sunlight than before? That can lead to sun scald. Willow tree root systems like to travel...far. How was the ground when you planted them? Their roots are strong but you can't expect them to grow in shale or other poor conditions.

Did they green up and then start the decline fairly quickly or did they not start dying until later in the summer?

I know last winter was really hard on fruit trees if they were pushing their northern boundaries.  Winterkill can sometimes happen like that, green up and then die back quickly in the spring.

eta:  I just understood they started looking bad last year late.  Probably  not winterkill.

Did you amend the hole with good soil or fertilizer or something when you first planted them?   I planted some trees once in a clay area, added good soil to a fairly large hole and let them go.  It took a few years before the roots got out to the bad soil and the trees just withered away.

This is what I'm thinking as well. Many people simply dig the size of the trees root ball or just a touch larger. They don't realize how far a tree's roots can extend.

Sounds to me like you got bores. Every see any perfectly round holes in the dead trees?  Almost like it was shot with a 22?  Willows are really soft and bores love them.  Lay their eggs in them.
The best way to treat is to implant insecticide pellets  near the base. It's then carried throughout the entire tree and kills the larve inside the tree.
No amount of spraying helps.