Thank you for your question. This one has me stymied, and I've asked another Master Gardener for her insight. She will bring it to her committee and try to come up with an answer for you. After that, I'll try to access this question again and give you what they find. 
Jeanne

Would you please take a look at this article, sent by the Master Gardener I mentioned in my last communication. And, please let me know if any of it resembles what's happening to your redbud.
Thank you.
Jeanne
Verticillium Wilt of Shade Trees Verticillium wilt is one of the most common and destructive diseases of shade and ornamental trees in Indiana. Redbud and hard maple trees are especially susceptible. In addition, Verticillium wilt attacks more than 80 other different tree species and many other plants, such as potato, tomato, rose, lilac, and snapdragon. In all, more than 300 plant species have been reported susceptible to this disease. Yews and conifers do not appear to be susceptible. Symptoms During midsummer, leaves turn yellow at the margins, then brown and dry. Sudden wilting of leaves on one or several branches may occur. Fre quently, the foliage on only one side of a tree wilts. The wood under the bark of wilting branches is discolored in streaks. The discoloration will vary from bright olive-green (maples) to chocolate-brown (redbud), depend ing upon the tree species and how long it has been infected. The discoloration might occur as distinct bands, streaks, or flecks in the sapwood. To examine for discol ored sapwood, cut into the outer sapwood at the base of branches showing leaf wilt; also examine the outer rings of wood at the cut end of a pruned branch for signs of discol oration. Host susceptibility and environ mental conditions influence severity of symptom development. Trees under drought, nutrient, or salt stress are more extensively invaded by this pathogen. An infected tree may die Fig. 1 - Sudden wilting and browning of foliage on one side of the tree is typical of Verticillium wilt. in a single season or linger on for many seasons, with branch after branch dying and being invaded by decay or canker fungi. Cause The soil-borne fungus, Verti cillium albo-atrum, causes Verti cillium wilt. Infection occurs through the root system. The fungus is an excellent soil inhabit ant, and produces resting struc tures that can survive in soil for many years. The fungi that grow from these structures can directly penetrate roots of susceptible host plants. Growth within the host occurs within the water-conduct ing tissues, resulting in blockage of water movement from the roots to the foliage. The tree responds to infection by plugging some water conducting vessels with gums and other materials, which further restricts water flow. “If a tree or shrub dies from Verticillium, never replant a susceptible tree or shrub back in the same location.” Fig. 2 - Cross-sections of Redbud stems infected with verticillium show brown solid bands in individual wood rings. Management Do not replant susceptible species where Verticillium killed a suscep tible host plant. If Verticillium wilt has been diagnosed in a landscape site, it is best to replant with a resistant plant since the soil can be contaminated with the Verticillium fungus for a long time. Replanting maples or other susceptible plants in areas where wilt has destroyed previous trees is inviting recurrence of the trouble. NOTE: Yews and conifers are resistant to Verticillium wilt. Redbud and smoke tree are especially susceptible. Refer to tables for a listing of resistant and susceptible trees and shrubs. When a tree or shrub exhibits mild symptoms, don’t be too quick to remove the plant. Prune out affected limbs and water and fertilize to maintain tree vigor. In some cases these tactics may delay progression of the disease for a number of years; however, infection is not cured since the disease originates in the roots. Verticillium wilt resistant woody plants Apple Beech Birch Crabapple Dogwood Fir Firethorn Ginkgo Hackberry Hawthorn Hickory Ash Azalea Barberry Boxwood Brambles Buckeye Black gum Black locust Box elder Catalpa Cherry & other Prunus Cork tree Currant Holly Honey locust Hornbeam Juniper Katsura tree Larch Linden Mountain ash Mulberry Oak Pawpaw Pear Poplar Pine Rhododendron Spruce Sweet gum Sycamore Walnut Willow Yew Zelkova Verticillium wilt susceptible woody plants Elm Golden rain tree Honeysuckle Horse chestnut Japanese pagoda tree Lilac Kentucky coffee tree Magnolia Maple Osage orange Persimmon Privet Redbud Fig. 3 - Redbud trees infected with Verticillium will have chocolate-brown streaking in the sapwood. Rose Russian olive Sassafras Serviceberry Smoke tree Sumac Tree-of-heaven Tulip tree Tupelo Viburnum Weigela Yellow wood The first and most important step before managing a tree disease is to accurately diagnose the problem. With an inaccurate diagnosis, more harm than good could be done, not to mention the wasting of both time and money. This publication is just one of several available online from Purdue Extension that addresses diseases found on landscape trees in Indiana. If your tree does not have symptoms similar to those de scribed in this publication, please check the others. Also, for more detailed photo graphs of disease symptoms, consider purchasing Common Tree Diseases of Indiana (BP-63). It presents information about the six most common tree diseases seen in Indiana. It is available from the Purdue Extension Media Distribu tion Center. The publication is $5 and can be ordered by calling 1 888-EXT-INFO. If you are still in doubt as to the cause of the problem, consult a professional such as the Extension Educators at your local Purdue University Cooperative Extension Service office or Purdue University’s Plant Pest and Diagnostic Laboratory (P&PDL). To submit a plant sample to the P&PDL for diagnosis, obtain a sample submission form from your local Purdue Extension office, from the P&PDL office (1-888-EXT-INFO), or from the P&PDL Web page http://www.ppdl.purdue.edu/. Detailed instructions for submitting most types of samples are included on the back of the forms. Submit a sample that is representa tive of the problem and shows the varying degrees of symptoms. Send several branches (even large ones) showing the symptoms and a detailed description of the problem and other useful information about the site, the age of the tree or shrub, and the date of planting. Photographs are very helpful. Send the sample and submis sion form by first-class or over night mail early in the week to: Plant & Pest Diagnostic Laboratory Purdue University 1155 LSPS West Lafayette, IN 47907-1155 REVISED 3/02 It is the policy of the Purdue University Cooperative Extension Service, David C. Petritz, Director, that all persons shall have equal opportunity and access to the programs and facilities without regard to race, color, sex, religion, national origin, age, marital status, parental status, sexual orientation, or disability. Purdue University is an Affirmative Action employer.

The other Master Gardener I mentioned has confirmed her diagnosis of Verticillium. Please read her email, below.

"I enlarged the section to show the stump staining that signifies Verticillium. It is visible in 3 of 4 cuts. The leaves themselves don’t change color until they shrivel up and die.  I think you could be fairly confident diagnosing Verticillium. And a certified arborist
to confirm.

Our literature states that Verticillium isn’t controlled easily but you can improve the tree’s life by promoting vigor. Water during dry periods, prune dead wood and don’t use a lot of fertilizer. Be sure to sanitize tools as Verticillium can be spread to other plants including susceptible perennials. They should not compost infected debris."

I hope all of this information is of help to you.
Jeanne

One more thing - to find a certified arborist, please go to:
https://www.treesaregood.org/findanarborist

Thank you for all the insight. Definitely unfortunate as there’s another 4 redbuds all in close proximity behind these three. 

Aside from the two out of the three at the front of the cluster the rest all look vibrant (will scrutinize for any stigmata of the problem on the others). Is there any potential benefit to preemptively removing the two affected ones no to perhaps limit spread as they continue to grow/spread roots?

Thanks again.

Todd

Hello again,
The following comes from Michigan State University. Please also remember to remove any leaves from the affected tree, bag and dispose of them. If you use any tools on that tree, clean with a 10 percent bleach/water solution. You might want to take this step with any of the other redbuds in that area.

I hope this information answers your question.

There is no fungicide treatment available to control verticillium wilt. However, some other measures may be taken to prolong the life and to improve the aesthetic value of an infected tree. Management of this disease includes proper pruning, watering and fertilizing. If so little of the crown is affected that branch removal will still leave an acceptable specimen then prune symptomatic branches back to their junction with the next largest asymptomatic branch. Severely infected trees, which would be unacceptable as landscape specimens after symptomatic branches are pruned, might just as well be removed completely.

Water during dry periods, especially if they occur in summer or fall. Fertilize if needed with a low nitrogen, high potassium fertilizer. Excessive fertilization apparently increases problems with this disease.

Do not replant in the same site with a verticillum-susceptible species because the fungus can survive in the soil for years. Instead, choose resistant or immune trees such as birch, ginkgo, sweetgum, mulberry, willow, hornbeam, hawthorn, honeylocust, crabapple, London plane, oak or mountain ash. Also, where maples are desired, be aware that red and sugar maples are more resistant than silver or Norway maples. Of the Norway maples, ‘Jade Glen’ and ‘Parkway’ have shown more resistance than other cultivars of the species.

There is no guaranteed way to get rid of the fungus once the soil has been colonized. Where the disease has been confirmed and the tree has been killed, replacement with a verticillium-resistant tree may be the only feasible option.