Use of fungicides is usually not necessary. However, applications can be made as soon as symptoms are visible. Among the compounds registered for use in Connecticut are horticultural oil, sulfur, potassium bicarbonate, and thiophanate-methyl. Consult the label for dosage rates and safety precautions. Gray mold, Botrytis cinerea .
Flowers turn a papery brown and become covered with gray, fuzzy masses.
Senescing flowers are particularly susceptible. Tan to brown spots with a target-like appearance can also develop on the leaves. These patches are often associated with flowers which have dropped onto the leaf surface. This disease is particularly troublesome during periods of extended cloudy, humid, wet weather. Good sanitation practices including grooming the plants and removing spent or senescing flowers can minimize the potential for infection.