I bought weeping pussywillow tree and left in pot for about a month but left outside in full sun. I transplanted it into the ground my soil is very dry and sandy so I added new soil and manure I also covered area with cedar chips. Shortly after leaves turned brown fell off and branches turned dark brown. I was told it needed more water so have been leaving hose on very low flow for several hours daily but still no signs of improvement. Is my tree dead or will it come back in spring, I have a year warranty on it.
There are several issues that maybe playing a a role in the symptoms you are seeing. Was the tree well watered when it was in the container? It could be that the tree was already under stress before you even placed it in the ground. Also, planting during the middle of the summer is a very difficult time for a tree to establish itself. With the heat and low rain fall any stresses on the tree can be amplified. It is often easier to plant in the early fall or early spring.
Some shoots might look dead but still be alive. To check if branches are alive carefully scrap off some of the outer bark. If the branch is green underneath then that branch is still alive.
Take a look at the trunk of the tree. Every tree has a flare near the bottom where the trunk widens right before the roots begin. It is very important that the entire flare of the trunk is above the level of the soil. If it is below the level of the soil it will break down the bark and eventually kill the tree. if the tree is too deep you will need to dig around the tree and raise it up.
Look around the base of the root flare and make sure there are no roots growing around the trunk if so the root can grow around the trunk squeezing it. It is best to remove any girdling roots.
You mentioned that you mulched around the tree. Make sure none of the mulch it touching the trunk, leave a small empty ring right next to the trunk so air can get to the flare.
When you water, have the water run slowly for for a long period of time. If you run the water for at least an hour the water will be able to soak down into the roots. Let the soil dry out before you re-water. You may find you are watering less often but the tree will do better. Small amounts of water do not make it down to the roots. With evaporation, run off and grass etc. competing for the water very little if any will make it to the roots.
Lastly, the addition of new soil and manure directly to the planting hole may bee a reason that the leaves fell off. It is recommended that one uses the soil that was removed from the hole to back fill. The reason for this is with high nutrient soil around the root ball the tree is less likely to send out it roots looking for nutrients and water. It can lead to a smaller, less stable root structure. Also, depending on how much manure you added to the planting hole, it could be that the already stressed roots were burnt.
For more details, see Planting a tree: a Toronto Master Gardeners Guide