Black Spot is a fungus that most commonly affects roses. You can identify Black Spot by the round, black spots – with fringed, often yellow, margins. The spots begin on the upper sides of leaves, gradually turning the leaves yellow before they drop. The spots can be up to ½ inch in diameter. Spots can also occur on stems, and plants can be completely defoliated. Black Spot is most prevalent in warm, humid weather with frequent rain.
- Plant resistant rose varieties.
- Avoid watering from above and prolonged wet foliage.
- Prune to keep plants open for good air circulation.
- Clean up and dispose of fallen leaves and prunings in winter.