Botrytis blight causes leafy shoots to wilt suddenly and fall over. The stem is covered with gray mold just above the soil. Spores are carried to young leaves and flower buds causing leaf blight and bud rot. The leaf blight stage occurs sometime after flowering. Recently opened flowers are also attacked. All infected parts turn brown and are later covered with gray mold. Cut and remove old growth. Do not plant peonies in basins that collect water. Do not heap soil around the base of plants. Sprays of benomyl control the disease.
Downy mildew causes entire shoots to blacken and die. Cankers form on the stem causing them to fall over. The crown may rot. Infected plants should be destroyed. No chemical control is listed.
Leaf spots may be a problem. Destroy plant residues in the fall. No chemical control is listed.
Peony leaf blotch is also known as red spot or measles. Small circular discolored leaf spots run together causing irregular blotches. The upper surface becomes dark purple, the lower surface light brown. On young stems the spots appear as reddish brown streaks. All parts of the plant may be spotted. Remove diseased residues at the end of the season. No chemical control is listed.
Crown gall causes the formation of rounded, rough galls. The galls are usually found at the soil line. Destroy infected plants and avoid infested soil. No chemical control is listed.
Anthracnose causes sunken stem lesions. The lesions may girdle and kill the stalk. No chemical control is listed.
Stem rot is worse in humid summers. The stalks are killed and a cottony mold form on the stems. Remove and destroy infected plants and plant parts. Drenches of benomyl may control the disease caused by Sclerotinia sclerotiorum.
Verticillium wilt causes plants to decline and die. Remove infected plants and avoid infested soil. No chemical control is listed.
Bud Blast is a noninfectious problem. The flower buds reach the size of a pea and fail to open. The problem is associated with lack of potassium, dry weather, low temperatures in early spring, excessive shade, deep planting and infertile soil.
Odema is caused by excessive atmospheric and soil moisture. Numerous small brown or purple spots develop on all parts on the plant above ground. This problem is usually not serious.
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|Botrytis on peony - 42K||Cladosporium on peony - 43K|