Peony shrubs bloom in late spring to early summer. The peonies used to fall apart after blooming but new types of peonies live long and produce red, pink, white and yellow flowers up to over 10 inches in diameter. The peonies, however, are subject to diseases.
Wilt causes stem tissue to discolor and shrink inwardly at the shrub’s base or below its flower buds. Fuzzy gray and black fungus grows on or in the stems.
Gray mold grows on leaves, often leaving a brown or orange slime on the stem, and in extreme cases the plant completely deteriorates under the dense fungi.
Some plant parts contain yellow or dark brownish-black markings in streak, fleck, mottle, mosaic or ring patterns. Viruses can lead to the stunting or distortion of the entire plant.
Similar to botrytis, this fungus affects stems, leaves and buds; however, fuzzy growth doesn’t develop. Instead, affected plant parts turn dark brown or black and leathery. Cankers may develop on the stem, causing them to fall, and the entire plant may eventually turn black and die.
Small red or purple spots develop on the top surfaces of leaves before blooming, then appear on the underside of leaves later. Despite how horrible they look, red spots don’t significantly affect the vitality of the plant.