The first two pictures look like predominantly powdery mildew, although there may be some leaf blotch present. The third photo looks like leaf blotch, also called red spot and measles, a common disease of peony caused by the fungus Cladosporium paenoiae.The symptoms vary from tiny red spots (“measles”) to larger brown or purple blotches on leaves and stems. The fungus overwinters on infected plant debris, and produces spores in the spring which are splashed onto young foliage and stems through rainfall or overhead irrigation. despite its appearance, this disease does not have a major impact on plant health and survival.

For both diseases the most important control measures are sanitation (cut the dead plant residues down to the ground and remove them in late fall or early spring before plants break dormancy) and using drip irrigation instead of overhead sprinklers when watering peony plants. You want to avoid wetting the foliage and providing a favorable environment for disease development.

a fungicide containing mancozeb ( Bonide mancozeb Flowable with zinc and Southern Ag Dithane M-45 are tow examples) applied  when new shoots are 2-4 inches high and again weekly until the flowers open can be used if the disease has been severe, but be sure to include sanitation and attention to proper watering. for powdery mildew, use a fungicide with the active ingredient potassium bicarbonate or horticultural oil.