black sooty deposit on holly leaves
My 5 year old standard holly has a sooty like deposit on the leaves, black and very clumpy. It will wash off but under the leaf are white strips with a brown dot, and these do not wash off. It is standing with ivy and clematis in a pot. Any idea or is it bin time?
Sounds like sooty mold, which you can learn about here: https://www.gardeningknowhow.com/plant-problems/disease/how-to-get-rid-of-sooty-mold.htm
The white strips and brown dot bit sounds like it might be scale insects, which are causing the sooty mold in the first place. When you're treating the sooty mold, you're actually getting rid of the honeydew-producing insects.