Black spot of roses
How to get rid of the fungus
The fungus mainly attacks roses, but also laurel. Small, black-brown spots spread in a star shape on the leaves, which turn yellowish and fall off.
Treatment
To control the fungus, remove the affected leaves early. Spraying with horsetail tea on several consecutive days can also reduce the spread.
Clemson University - USDA Cooperative Extension Slide Series, CC BY 3.0 US https://creativecommons.org/licenses/by/3.0/us/deed.en, via Wikimedia Commons