Ask Mr. Smarty Plants

So sorry that your Texas redbud (Cercis canadensis var. texensis) didn’t make it.  The Native Plant Database on the Lady Bird Johnson Wildflower Center says the following about the Texas redbuds. The redbuds of eastern North America have long been popular for their pink-purple early spring flowers that appear on bare wood before the leaves emerge. Texas redbud is the appropriate variety to use if you live on limestone soils from southern Oklahoma through central Texas to northeastern Mexico. It is drought-tolerant within its range, prefers dappled shade but is also found in full sun, and can do well even on relatively thin soils. Its glossy, rounded leaves bring welcome shade and its flowers attract pollinators.

Texas redbuds do like well-drained, calcareous, rocky, sandy, loamy, or clay soils, usually limestone-based. It is drought- and cold-tolerant within its range. Give it dappled shade when young. A selection called Sanderson is said to be the most drought-adapted Texas redbud cultivar.

The USDA Forest Service does include a few challenges for Texas redbuds on their website.

They note the following: the bark is thin and easily damaged from mechanical impact; susceptible to breakage either at the crotch due to poor collar formation, or the wood itself is weak and tends to break; susceptible to verticillium wilt.

Texas redbud should be grown in full sun or partial shade on moist, well-drained soil. It is highly drought tolerant once established and grows well in all areas within its hardiness range.

Canker is the biggest problem with Redbud. The fungus enters through wounds or dead and dying branches. Dieback begins as a canker on a branch. The cankers, at first small and sunken, enlarge to girdle the branch. Bark in the canker turns black and a crack forms between diseased and healthy bark. Once girdled, the part of the stem beyond the canker wilts and dies. There is no chemical control. Prune out diseased branches.

Leaf spots can be a problem during wet weather. Since the disease is rarely serious, no chemical controls are suggested.

Verticillium wilt attacks and kills Redbud. Fertilize affected trees and prune out wilted branches.

The Missouri Botanical Garden has a good article on verticillium wilt on their website which says that verticillium wilt is a fungal disease of over 300 host plants, including a wide range of garden and greenhouse crops in addition to woody ornamentals, most noticeably elms, magnolias, maples, redbud, and viburnums.  

Verticillium wilt is a fungal disease of over 300 host plants, including a wide range of garden and greenhouse crops in addition to woody ornamentals, most noticeably elms, magnolias, maples, redbud, and viburnums. (See following list for a more complete list of susceptible plants.) Caused by the soil-borne pathogens Verticillium dahliae and V. albo-atrum, these wilts are prevalent throughout the tropical and temperate regions of the world. They exist in the soil primarily as mycelia that infect belowground plant tissue. High summer temperatures tend to halt development of the disease. Groups of plants resistant to verticillium wilt include gymnosperms, monocots, members of the rose family, oaks, dogwoods, willows, rhododendrons, azaleas and others.

Symptoms of verticillium wilt vary somewhat in different host species and also within species due to varying environmental conditions. These might include sudden wilting of small branches, yellowing of foliage, stunting of growth and premature defoliation. Sapwood of infected branches typically has olive-green to black streaks. Vascular tissue appears as a dark ring in cross sections or pin-point dark spots. The initial symptoms may occur on only one branch or may involve the entire plant. Oddly, following the initial symptoms, there may be no sign of the disease for several years, even though the infection continues to reduce plant vigor.

Verticillium species are opportunistic fungi that persist in the soil as saprophytes. Infection begins in the root area where the resting hyphae of Verticillium germinate and penetrate feeder roots. The fungus also can enter wounds in the root area. The disease spreads within the plant by mycelium or spores called microconidea that travel in xylem vessels to other parts of the plant.  Water flow is restricted and the plant wilts. The entire plant may die quickly or may die section by section over many years.

The recommendation is to plant verticillium wilt resistant or tolerant species. There is a list of susceptible plants to avoid as well as resistant or immune ones on the Missouri Botanical Garden website.  Purpleleaf plum (Prunus sp.) is not recommended if verticillium wilt has been an issue in the past.