Unfortunately, trees that are leafless in the peak of the growing season are either dead or so weakened that they are beyond salvaging. As to what caused the Redbud's demise, it's hard to determine; many factors can play a role in tree death, and often they overlap or occur consecutively. Usually, the first factor is stress from environmental conditions, and then progresses to opportunistic pests or disease. These infections or infestations cause their own stress for the tree, and the cycle spirals into tree decline from which they rarely recover. We don't see clear signs of pests or disease here, but some can be hard to detect from photos.

Soil moisture level is a common element in tree stress in home landscapes: either too much (through over-watering or poor drainage killing roots) or too little at key times, such as in summer and autumn when trees need to prepare tissues for winter dormancy as well as grow the leaf buds for the following year.

Symptoms of both moisture issues look alike, so without an inspection of the root system, it's hard to tell which it may have been. If last year's foliage wilted all at once and became off-color, that suggests the soil was too wet. When foliage instead starts to "burn" (turn brown and crisp) from the outer edges, and only younger foliage wilts first, that suggests under-watering. These are not concrete distinctions, though. Additionally, too little or too much moisture in autumn, when leaves are shedding, or during the dormant winter season, is harder to detect since there aren't any above-ground symptoms.

Was any herbicide applied to control weeds in the lawn, especially near the tree, in the last few months? Some chemicals carry a warning on the label about applications too close to trees and shrubs, as they can be absorbed and cause damage.

The tree does look like it's planted too deeply, though it could be that too much mulch is covering-up the trunk base for us to tell for sure. The root flare - where roots begin to branch off of the trunk base - should sit just at the soil surface. Mulch is quite useful around trees but it shouldn't touch the trunk itself. When trees are planted too deeply, the roots can be deprived of oxygen as the depth of soil they're accustomed to changes, and the extra soil up against the trunk can encourage the formation of girdling roots.
https://extension.umd.edu/resource/girdling-roots

If the soil drains well and doesn't tend to stay wet, you should be able to replant a Redbud or another tree in that area once this one is removed. (If it is wet and the drainage can't be fixed, other tree species aside from Redbud would be better suited to those conditions.)

Miri

You're welcome, Gary.

Here is what to look for when examining roots (the finer roots, not the thicker, woodier roots):

• those that succumbed to rot will probably pull part fairly easily with a tug, where you will have the inner core pull out from the outer sheath
• soil that had been too wet may have a pronounced musty or sour smell, though this isn't always detectable
• those that succumbed to drought damage or non-rot causes of dieback will probably snap in two cleanly, and with a bit more effort than what would be required to pull apart rotted roots

Complicating things is secondary rot, which may have set in to start decaying roots after another, unrelated factor caused their death. The longer the plant has been dead in the ground, the more likely this could obscure the original symptoms of tissue damage.

One more test you can do, though it may not be too informative if the tree has been dead for some time, is a "scratch test" in several places in the canopy.

• on any branch, use a pruner blade or pocket knife to scrape a strip of bark off; the exposed area only needs to be around an inch long and quarter-inch wide or so, just to give you enough to look at; avoid cutting too deeply so you don't miss the cambium layer ("sapwood")
• if scraping is too tricky to do at the right depth, you can prune off the entire stem and look at the cut end cross-section
• sapwood transports moisture, nutrients, and sugars around the plant, and lies just under the bark itself, though on very young stems it can appear in the center of the twig; the core of an older branch is naturally-dead wood
• if the sapwood is still alive, it should be green (possibly cream-colored) and will probably feel a bit moist; dead sapwood is noticeably dry, and white, brown-gray, or streaked with darker brown stains
• streaking/staining of the sapwood can indicate an infection from a fungal or bacterial pathogen; these kill or clog the sapwood, preventing it from keeping the foliage, branches, and roots alive (depending on the exact disease)

While finding live sapwood doesn't necessarily mean the tree will recover, it might help determine where the problem originally began. Live sapwood could still be dying slowly as it dries (especially since it functioned well enough to allow the flowers to open this spring), but suggests that the roots were ailing and not functioning properly. Dead sapwood suggests that something (physical or chemical injury, infection, insects) interrupted the flow of fluids from the roots to the branches. These are not concrete conclusions as other factors can complicate matters, but they might help shed light on what happened.

Lastly, Verticillium Wilt is a disease Redbuds can contract, though there are additional vulnerable tree species. It is known for causing the death of a tree fairly rapidly, and might explain why the Redbud flowered earlier. You can look through the information on these pages and see if that's a suspect for causing the tree's condition, even though there's nothing you can directly to about it at this point:
https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/pests-and-problems/diseases/cankers/verticillium-wilt.aspx

https://www.uaex.edu/environment-nature/forestry/health/BP_6_W.pdf

Miri