Many crape myrtle trees across the D.C. region are infested by a bug called bark scale, which leaves behind a black fungal infection. A cure is elusive.

In Texas, T. V. Munson’s Denison Nurseries listed pink, crimson, and purple crape myrtle in 1885, while in Frelsburg J. F. Leyendecker’s Pearfield Nursery catalog of 1888 said it was “too ...