🍄Fungal diseasesModerate
Black Spot (Roses)
Risk near you, next 48h
See whether your local forecast favours this disease right now.
When it strikes
Temperature
18–27°C
Humidity
≥85%
Leaf wetness
Required
Season
Spring, Summer
About
Black spot (Diplocarpon rosae) is the most common and serious disease of roses worldwide, defoliating bushes through warm, wet summers and weakening them before winter.
Symptoms
Rounded black spots with feathery, fringed margins on leaves, surrounded by yellowing; affected leaves drop early, leaving bare canes.
Organic Treatment
Remove infected leaves and prunings, spray sulfur, copper or a baking-soda solution weekly in wet weather, and mulch to reduce splash.
Chemical Treatment
Myclobutanil, tebuconazole or chlorothalonil every 7–14 days during the infection season.
Prevention
Grow resistant varieties, space bushes, prune for an open centre, water at the base early in the day, and clear fallen leaves.