The upper surface of the leaves on my mature holly bush Golden King is covered with a black sooty mould, which can be washed off.A young small holly alongside is now similarly affected. Other evergreen shrubs alongside are NOT affected.Under surfaces of leaves have browny ? mites, and/or raised white patches. Can you suggest cause and solution please ?
The moulds are just a symptom and the insects are the cause and the problem can be solved by waiting until natural predators and parasites build up, or by spraying with a garden insecticide. This cna be difficult to acheive with a tall bush.