Pest
Management Home Page Dr. John F. Baniecki The most common disease of the garden peony is Botrytis blight which is often called gray mold. This disease is caused by two species of fungi, Botrytis paeoniae and B. cinerae that produce numerous spores on the plants giving the characteristic gray color--hence the name "gray mold." Stems, buds, and leaves of peony are affected by the disease that causes the young stalks to suddenly wilt and fall over in the early spring. Young buds turn black and dry up, whereas the older buds that become infected later, turn brown and become covered with a gray mass of fungus spores. Even opening buds may be destroyed. Leaf blight usually occurs sometime after the blooming season with large irregular brown areas appearing on the leaves and spreading widely. Usually the stalk below the infected buds is decayed for a short distance below the neck, and in severe cases, crown and root rots may occur. At the base of infected stalks, small, black hard bodies can be found that are called sclerotia. This sclerotial stage is the means of overwintering for the fungus and can be found in infected plant parts that fall to the ground. |
