Careful pruning of old canes helps to eliminate rust carry-over on the canes and promotes air movement and drying of leaves. Hybrid teas, as well as old-fashioned varieties, are susceptible. Worldwide, this disease seems to be of little importance, as there is virtually no documentation of it in the literature. Symptoms occur as leaf spots, sometimes running together. Newly formed spots are red or purple.
Older spots have white centers with a dark red margin.
Defoliation may occur if the disease is severe. Botrytis blight mainly affects hybrid tea roses. The fungus attacks leaves and canes, prevents blooms from opening, and often causes flower petals to turn brown and shrivel. To diagnose it, look closely at cankered stems, brown leaves and flowers. If the fungus is present, the affected areas often are covered with a grayish-brown fuzzy growth.