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Peony Diseases

Informational table showing disease name, symptoms, pathogen/cause, and management of Peony diseases.
Diseases Symptoms Pathogen/Cause Management
Bacterial blight Spotting may be accompanied by rings of dark red pigment or sometimes yellow haloes. Xanthomonas Maintain good air circulation. Promptly remove and destroy plant debris at season end. Avoid overhead irrigation.
Botrytis blight Young shoots discolor, wilt, and fall over. Later, browned buds and blighted leaves may develop masses of gray, fuzzy fungal spores. Botrytis cinerea or Botrytis paeoniae Avoid overhead irrigation. Maintain low humidity. Remove infected plant parts. Clean up debris at season end. Apply a fungicide to protect plants.
Crown gall Galls or overgrowth of tissue form at the soil line or along the stems Agrobacterium tumefaciens Remove infected plants and surrounding soil. Avoid wounding plants at or near the soil line.
Leaf blotch or measles Small, reddish spots that can coalesce to form large, irregular purple blotches on leaves and stems. Lesions are also formed on stems. Cladosporium paeoniae Avoid overhead irrigation. Maintain low humidity. Remove infected plant parts. Clean up debris at season end. Apply a fungicide to protect plants.
Nematodes Plants are stunted and yellowed. Small galls occur on roots or roots have little branching Meloidogyne, Rotylenchus, Ditylenchus Remove infected plants and do not replant there for one year. Till the soil to keep it weed free for one year before replanting.
Phytophthora blight Infected parts become dark brown to black and somewhat leathery, and shoots may die. Crowns may also develop a dark, wet rot. Phytophthora Avoid planting in wet or poorly drained areas. Remove and destroy infected plants.
Powdery mildew Foliage becomes coated with white mycelium. Erysiphe When mildew is observed, apply a fungicide to protect plants.
Root rot Plants are stunted, yellowed, wilt, and die. Fusarium, Rhizoctonia, or Thielaviopsis Remove infected plants.
Southern blight Stems turn water-soaked at the base, then wilt. The base of diseased stems will often show fans of thick, ropy-textured fungal mycelium and numerous, tiny, spherical sclerotia that turn from white to brick red as they mature. Sclerotium rolfsii Destroy infected plants.
Verticillium wilt Wilting of shoots in the absence of damage to the crown. Verticillium albo-atrum, V. dahliae Remove and destroy infected plants, and do not replant peonies.
Viruses, Ringspots, light and dark green mottling on the leaves, stunting, curled leaves, and poor growth. Tobacco rattle, Tomato spotted wilt, Alfalfa mosaic viruses No treatment is recommended if plants are only mottle but are growing well. Stunted plants and those not growing well should be removed.
White mold Can cause stem rot on peony. The entire plant may wilt, or only a portion of it. Infected areas of the stem turn a light tan color and may become withered and stringy. Under wet conditions, fluffy white fungal growth (mycelium) often appears. Sclerotinia sclerotiorum Do not replant in infested areas. Maintain good air circulation.

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Peony Diseases

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