Remove and destroy all infected leaves, including those on the ground. Avoid overhead watering because the fungus spreads in water. To prevent the disease, spray with a fungicide every 7 to 10 days in cool, wet weather. A clear, sticky substance that attracts ants appears on foliage. They suck the juice from the plant and secrete the sticky substance.
Aphids can carry and spread diseases.
Aphids may be knocked off plants with a stream of water. In severe infestations, spray with an insecticide or an insecticidal soap. Small, rounded holes appear in leaves. Eventually, the entire leaf surface between the veins disappears. Rose slugs, the larvae of sawfly wasps.