Unfortunately we can't determine the exact cause of the leaf symptoms pictured, though can say that if it is due to disease, there is no treatment that would cure it, as fungicides cannot reverse existing infections. We can't see enough detail to rule-out spider mite damage, as their feeding can contribute to leaf browning, but you can use a magnifying glass to look for indications of their presence on the leaf undersides. Spider mites thrive in the kind of hot, rainless weather we've been having. (Silken webbing, which gives them the "spider" part of their  common name, won't always be prominent with outbreaks of these mites.)

The distortion in the lowest leaf of the trio pictured somewhat resembles herbicide exposure damage, though we can't be certain. Was any weed killer used in the lawn in the past several weeks, or potentially sprayed on a breezy or hot day in a neighboring yard? Redbuds do seem to be keenly sensitive to drifting herbicide, though research has not demonstrated which chemicals in particular might be responsible, and in which circumstances. (Dicamba, a common component of many herbicide products, is known to affect trees and shrubs in general.) If herbicide is behind the leaf stunting and distorted shape, it does not look too serious in this case, since otherwise more foliage would be affected, and with greater severity. There is no remedy for exposure to herbicide other than giving the plant time to grow out of the damage.

There might be a leafhopper shed skin in one of the images of the leaf undersides, but it's not clearly visible and might be unrelated debris. Leafhoppers are very common on a variety of plant species, and their feeding (as sap-suckers) can sometimes lead to leaf damage, especially in hot weather. Despite being an eyesore if damage becomes heavy, no treatment with insecticide is needed or recommended, nor would using one work very well to suppress them.

Another potential cause of leaf damage among sensitive plants is air pollution, like from poor air quality days and ground-level ozone, though we don't know how inclined redbuds in particular are to developing such damage. (It manifests more often on the foliage of certain vegetables.)

Overall, the tree appears to be in good health. For now, just keep monitoring it for watering needs given our ongoing drought, especially since last year's drought may compound any stresses on the tree that could predispose it to opportunistic infections like Botryosphaeria canker.

If new or worsening symptoms develop, feel free to submit additional photos for assessment.

Miri

Thank you for your help.  There is similar damage to nearby azalea bushes, so I'm thinking your suggestion of spider mites might be the cause.  What should we use to control the mites?  I went to the link on spider mites, and after reading the information, I'm thinking several treatments with oil spray might be worthwhile.  The tree is only about 10 ft tall so we can easily reach all of it with spray, and of course, treat the azaleas too.

Hello Patti,

Azalea foliage tends to succumb to lace bug damage more so than spider mites (especially if they are exposed to full sun or lots of afternoon sun), though both are possible. Treatment options for lace bugs are included on the linked page.

I would not treat for mites right now -- temperatures for such sprays need to be below 85 degrees, and foliage damaged by insect feeding plus heat stress may "burn" from application of a pesticide. (That is, the pesticide itself will cause some leaf damage, and potentially worse than the mites themselves were causing.) You can spray the leaf undersides with a strong spray of plain water from a garden hose (make sure the water runs cool first, of course), which will help knock some insect or mite pests off the foliage (for both the redbud and the azalea), but hold off on other treatments for now. Plus, we aren't certain mites are responsible for the redbud's symptoms (unless you saw mites with a magnifying glass or did the "tap test" by knocking them off the leaves onto a piece of white paper for easier viewing), so treatment with an insecticide/miticide isn't warranted until they can be confirmed to be the culprit.

Miri

You're welcome!