The holly leaves are covered on the top with a black soot like covering which will rub off. Underneath the leaf I notice white deposits, not spots but small lines, which also rub off. Thank you.
Certified GKH Gardening Expert
It sounds like sooty mold, which is a symptom of several kinds of pests, such as scale or mealy bugs, that can attack hollies. I recommend treating the plants with neem oil. This will kill any pests on the plant and treat the sooty mold as well. These articles will help: https://www.gardeningknowhow.com/problems/pests/neem-oil-uses.htm