Unfortunately, the prognosis does not look good.
The gummosis (the jelly-like substance pushing out of the tree) is indicative of bark injury. This could include accidental mower/trimmer injury, disease or boring insects. The tree pushes out this sap to try and exclude invaders. 
In our area it is commonly related to the Peachtree borer, especially if you can see any sawdust-like frass stuck within it.
Once they are within a tree there is not much you can do.
Ornamental cherries tend to be relatively short-lived (compared to say, shade trees) and can start to decline at about 20 years, but you can generally enjoy them for as long as they are attractive to you.
Here is our page on Ornamental Cherries and their problems: 
https://extension.umd.edu/resource/ornamental-cherry-trees-identify-and-manage-problems/ It's possible that there could be a related canker disease at work as well.
Often you can extend the life of the tree a bit by reducing stress, like keeping it watered in times of drought, and making sure that mulch is no deeper than 2-3 inches and kept pulled back from the trunk. However, last season we had prolonged periods of serious drought that stressed all of our trees and as we hit this period of high heat and lack of rain, some will not be able to survive.
You could give it a good, slow, long drink but it may not make much difference at this point, I am sorry to say.

My much-beloved weeping cherry succumbed years ago but was in a place (back of my house outside a window near my birdfeeders) where I could leave it to naturally decline and die(usually limb by limb). Over many years it has served as food (woodpeckers, nuthatches and others hunt and eat insects under the bark, tree frogs have been found there too, and bluebirds and many others often perch there before feeding. (My point being, dead trees have a good deal of environmental value).


Christine
 

Hi Christine,

Hello Liz,

Generally, canker diseases and wood-boring insects that can kill trees tend to target trees under stress (from drought, over-watering, injury, or other factors), rather than healthy trees. You can make sure the front yard cherry is not planted too deeply or over-mulched, since covering the root flare can lead to long-term health problems for a tree that can't always be treated. (Girdling roots being a common consequence. The linked pages provide more information.)

Japanese Maples aren't vulnerable to the exact same array of pests and diseases that cherries are, but when stressed, they too have certain vulnerabilities to their own canker and borer issues. Planting depth and root flare exposure apply to them as well, as it does to all trees; maples are notorious for developing girdling roots if planted or mulched too deeply.

Watering to relieve drought while not over-watering will help ease trees through harsh weather. When monitoring for watering needs, feel the soil about six inches deep in the plant's root zone and water thoroughly only once it becomes somewhat dry to the touch at that depth. If damp when checked, watering is probably not needed. Make sure any roof downspout outlets that might be nearby empty away from the root zone, as cherries (and to a lesser extent, Japanese Maples) can decline if the soil is too wet too often.

Fertilizer application risks worsening the problem when used for any ailment except a nutrient deficiency in the soil, which can only be accurately determined by a soil testing lab. Roots struggling with drought or which are too wet and dying back cannot make use of the added nutrients, and the soil itself isn't necessarily lacking in the nutrients anyway. Surplus nutrients that a plant can't put to good use can also benefit the pest or disease in question, or at the very least, they will be wasted since they're not well-absorbed.

You could try to gently scrape off the congealed globs of sap if you want, but it's not going to help the tree at all, other than improve its appearance for the short term. Nothing should be removed if doing so will injure the bark, which is the tree's main defense against borers and trunk infections.

The narrowed portion of the upper trunk is just the graft union -- the place where the weeping part of the tree was joined (grafted) onto the trunk and root system, which itself is not a weeping form. (Sometimes weeping cherries are not grafted up top and are just trained on their own trunk instead, but that's a slower process that increases tree cost and time to market, so it's not widely practiced. It's quite typical for weeping cherries to be grafted in the way that your tree is.) If the trunk growth, which increases in girth with age, outpaces the top growth, then the diameter difference above and below the graft point can become obvious as a tree ages, where it might have been less noticeable when it was younger. "Graft incompatibility" can happen when graft unions don't keep functioning well over time (the water and sap-conducting tissues under the bark don't stay well-aligned or keeping pace with each other's growth), but in such cases, the top growth tends to die off, and nothing can be done. While the tree pictured is losing its canopy, we don't think the graft union is the cause, especially given the heavy gummosis.

Miri

Hi Miri,

You don't have to remove any soil, as it doesn't pose a significant health risk to a new planting. (Any soil-borne plant pathogens, if present at all, are so commonplace that they could easily re-colonize new soil anyway at some point in the future.) If you wind-up having to fill-in a depression left by whatever soil clings to the roots when this tree is removed, then compost or good-quality topsoil can be useful amendments to help maintain drainage; just make sure they're well-blended with the soil surrounding the root ball if they are used.

Miri