Rose Black Spot

Symptoms: Black spots on leaves. They can be seperate or enlarge and join together. As seen in the photo, the leaves can turn yellow. They can also fall prematurely.

Cause: This is caused by the fugus Diplocarpon rosae. This seems to overwinter in the lesions on stems, bud scales and on fallen leaves.

Control: Dispose of infected leaves promptly. During spring prune out stems with lesions. Fungicide treatment is available, but if the infection isn't too bad then the plant isn't affected too much.