when you say you water it daily. how is it watered (by hose, dripper etc) and for how long? If you are only watering a few minutes a day you really need to change your watering practice. Proper watering is slow and deep but less frequent. oozing of sap occurrs naturally in some tree species, but can also be coused, by over or under watering.
But since it is only one that is having problems,
look around for other sources of the problem. Such as, is it the closest to the neighbors... if so, ask the neighbor it they used a weed killer lately. Especially a weed & feed on grass. look really hard, are there any insects involved? The leaves that are dropping are they brown or green?
RE: the sticky substance...is it in just one place on the tree, does it cover the trunk.
Does the sap smell bad (slime flux)?

please give as much info as you can, we just may be able to figure it out.

Are they "true" willows (Salix) or are they desert willows (Chilopsis linearis), or some other type of willow?

they are Salix. they get watered by hoseinto tree wells. and occasional. deep root. the leaves turn light brown and fall off then the end branch falls off.

Willows are very prone to stress diseases here in the valley. It's too hot and dry for them. Sounds as if yours is on its way out. If it is, consider replacing it with something more desert adapted, such as Shoestring acacia or Australian willow. Both have a willow look but tolerate our conditions better.

thanks all for the help

We have had a willow tree for 4+ years. Snow had broken the tree in half so I sawed off the large branch and sprayed the wound with Black tree spray. A year has passed and the tree is doing fine except at every "Y" in the willow tree there are huge amounts of white foam looking sap running out of the tree. It is attracting all kinds of insects and almost has a fermentation smell to it. Can you help me with some kind of answer as to what I should do please? Thank you very much