Rose black spot is a fungal disease of roses – the commonest and the most serious and devastating.
The symptoms can vary from rose to rose and from year to year.
It usually starts as black or dark purplish spots or blotches on the leaves, which rapidly spread across the leaf. These are usually followed by the leaf turning yellow around the spots/blotches. The affected leaves usually drop prematurely from the plant, and badly affected roses can shed nearly all their leaves. If lots of leaves drop, then this seriously weakens the plant and subsequently can reduce flowering.
Attacks year after year will seriously weaken the plant, causing severe dieback and greatly reduced glowering performance.