Plant Health Problems See Perennials for a detailed discussion of problems that may occur and are common to most herbaceous ornamentals.
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.