The growths on the bark are lichen, a harmless organism (looks like more than one species is present in the photos) that does not cause disease in plants; they merely attach to the bark to absorb sunlight and rainwater. If a plant with lichen is ailing, some other factor is the cause.

We're been trending dry lately, and the wilting might just be water stress. Is the shrub being monitored for watering needs by feeling the soil moisture level around five inches deep in the root zone? Even if a nearby plant is watered with the same frequency, differences in soil moisture retention and drainage may explain why this one is struggling. Beautyberry is similarly stressed by being over-watered, and wilting can unfortunately be associated with both over- and under-watering, or infections in the lower stems. If a wilt disease has taken hold, there won't be any effective treatment or cure, but see if soil moisture is the main reason first by observing whether the foliage continues to wilt for a day or more after the root zone is adequately rehydrated.

Miri