Redbud leaf curling/cupping is often caused by:
If you see your redbud trees leaves have yellow spots or the leaves have started wilting and curling. You may suspect that the tree is infested with spider mites. Adult spider mites are reddish-brown or pale in color, oval-shaped, and tiny (1/50 inch long). These insects feed by piercing leaf tissue and sucking up plant fluids, which causes the leaves to turn yellow, curl, dry up, and drop off.