EN

Black spot of rose: how to recognise and treat it

Disease

Black spot of rose — Photo: Stephen James McWilliam, CC BY 4.0, Wikimedia Commons

Symptoms

Purple to black spots with feathery, radiating edges on the upper side of leaves, often with yellowing around them.
Spotted leaves drop early, even when the rest of the leaf is still green; badly affected bushes lose almost all their leaves by midsummer.
Purple-red blotches or small black scabby lesions on young canes.
Weakened plants that grow less and flower less.

Organic treatment

Collect and destroy fallen leaves, or bury them under mulch; remove spotted leaves as they appear.
Prune out canes with lesions in spring before the leaves appear.
Spray neem oil, potassium bicarbonate or sulphur, which reduce black spot; follow the label.

Chemical treatment

The RHS advises against fungicides. If you use one, myclobutanil, propiconazole or chlorothalonil, where approved for home use, protect new leaves when sprayed from the start of the season; follow the label.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Prevention

Keep leaves dry — water at the base, and if you wash or water plants, do it in the morning so leaves dry before evening.
Plant roses in full sun with enough space for air to move around them.
Newer cultivars sold as resistant give only a few years' respite; old species roses are little affected.
Pick off any leaves that stay on the plant over winter — the fungus overwinters on leaves and young stems.

Plants it affects

Rose

Sources

Figures checked against these sources.