As the common cold is to humans, this must be the most common rose disease and there are very few cultivars totally resistant to it, although some fair better than others. A few black spots are not that unsightly and the fact that a rose may get black spot should not be a reason for not growing it.

The disease is usually most noticeable from mid-summer onwards although the odd variety may succumb badly before this, especially after a mild winter as Black spot spores can be air borne and are occasionally carried from one plant to another on the blades of secateurs. When they find a suitable leaf to settle on they will not be seen until small round-ish patches of black or dark brown appear, these will soon multiply; the areas not spotted will become yellow and eventually the leaf will fall.

Fallen leaves should be collected and burnt where possible, as the spores will over-winter in shallow soil where they will remain ready to begin their destruction the following year. In the worst scenario the spores will infect branches and unless tackled this is when the whole plant is at risk. Cut away what you can and apply a winter wash with a mild sterilant, there are now several available that will successfully deal with fungal diseases such a black spot. A regular wash with the hose is also recommended as this will wash the spores away from the plant on which it is harbouring. Some say that black spot can be deterred by spraying the plant with a solution of skimmed milk, but I have never tried doing so.