Make sure your peonies have good air circulation, are in well-drained soil, and receiving sunlight. When botrytis appears, it’s very important to clean up the peony patch of all plant debris in fall, putting it out with the trash. What disease are you trying to control in your peonies? Botrytis blight. Spots on peony leaves or mold on the plants is usually caused by one of two peony fungal diseases, botrytis blight (gray mold) or leaf blotch. Although there are several species of the fungus Botrytis which can cause blights; the most common is Botrytis cinerea. Botrytis is a fungus that affects peonies, especially in a rainy year. Eventually, if left untreated, botrytis will … Powdery Mildew? These diseases tend to flare up in wet weather and plants that are infected early in the season may have severe leaf damage by late summer. Also, follow good sanitation practices, such as removing dead or infected blooms and buds. You need to look for a product that says on the label that it can be used on the specific type of plant, peony, and the specific disease, for instance, Botrytis blight. There are fungicides that can help protect your plants from Botrytis blight. When peony buds don’t develop, you can still assign the problem the name of bud blast. Botrytis Blight of Peony: Botrytis paeoniae Symptoms and Signs Management Strategies Disease Cycle Botrytis blight or gray mold is a fungus disease which infects a wide array of herbaceous annual and perennial plants. Peonies with mildew and leaf blotch disease What’s worse, the fungus can strike invisibly, turning a shipped box of seemingly perfect flowers into a brown-streaked mess, leading to upset customers and cancelled payments. By: Carla Locke ... Botrytis blight is a fungal disease that is caused by wet spring and summer weather. This disease generally appears in spring or early summer when the shoots of affected herbaceous paeonies wilt and turn brown for no apparent reason. Stippling the peony’s emerald leaves with unsightly blotches of brown and purple, Botrytis can ruin up to half of growers’ crops long before they’re ready to sell. What Causes Peony Bud Blast? Phytophthora Blight. Botrytis Blight? Experts used to say that this condition, termed bud blast of peonies, was caused by botrytis blight, a fungal disease. Symptoms include blackening of flower buds that then fail to open as well as blackening of leaves, starting at the edges and moving backwards to the stem. Treatment of leaf blotch includes removal of infected parts, application of appropriate fungicide and watering only at the base of the plant. Now it is recognized that these problems with peonies are often caused by improper cultural care. Peony Plant Diseases. Powdery mildew is another of the common peony diseases which covers leaves with a white powdery coating. Peony wilt is an infection of the leaves and stems of peonies and tree peonies by the fungus Botrytis paeoniae, which is closely related to the grey mould pathogen Botrytis cinerea. In this case, it could also be caused by Botrytis paeoniae, which only infects peonies.