Answer: Peonies are occasionally subject to foliage problems. The best defense is to clean up the peony bed each fall, carefully removing all the old stems and foliage and replacing any old mulch with fresh mulch. This should help a lot to stop the reinfection next year. During the growing season, remove any foliage that begins to show signs of infection and avoid overhead watering, particularly in the late afternoon, evening, or at night as damp foliage can encourage the problem to spread.
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