Powdery mildew - a common fungal disease. Affected leaves are removed and fall off. Typical signs - education on leaves, stems and pedicles are grayish-white powdery coating. Control measures. Sprinkle with special biological agents to combat powdery mildew. For the prevention of powdery mildew of roses and euonymus have a good pollination gray 3-4 times over the summer.