This is not a disease -- this is damage from the frost/freeze that much of Maryland experienced last week. In some cases, only certain leaves (or branches on woody plants) were affected, and in other cases, the entire plant was damaged, which is why the pattern of freeze-killed tissues looks irregular.

Hardy plants do not retain their freeze tolerance once they have broken dormancy and begun to produce new growth, which is why temperature swings between very mild days and cold snaps in spring can be very damaging. We've received many inquiries about such damage on a variety of tree, shrub, and perennial species that had begun to grow or leaf-out when the we had a freeze overnight.

Nothing can heal the injured tissues, but healthy and well-established plants usually have enough energy reserves to produce new growth, though it may take them a few weeks to start to look normal again. It would be best to wait to see how the plant fares, though you can certainly snip off any damaged leaves now so they don't become mushy and harbor mold. (Otherwise, the singed leaves will eventually fall off on their own as they wither more and dry out.)

We are still in a worsening drought, carried over from the past two years of insufficient rain. It would reduce plant stress to monitor them for watering needs and irrigate them periodically as needed. The linked page has watering guidance. Producing new growth requires ample root moisture, and the process can be hindered or stalled if a plant is too drought-stressed.

Miri