When peony buds don’t develop, you can still assign the problem the name of bud blast. Also, follow good sanitation practices, such as removing dead or infected blooms and buds. Peony Plant Diseases. 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. 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. Treatment of leaf blotch includes removal of infected parts, application of appropriate fungicide and watering only at the base of the plant. There are fungicides that can help protect your plants from Botrytis blight. Although there are several species of the fungus Botrytis which can cause blights; the most common is Botrytis cinerea. Experts used to say that this condition, termed bud blast of peonies, was caused by botrytis blight, a fungal disease. Powdery mildew is another of the common peony diseases which covers leaves with a white powdery coating. Now it is recognized that these problems with peonies are often caused by improper cultural care. What disease are you trying to control in your peonies? Peonies with mildew and leaf blotch disease Botrytis is a fungus that affects peonies, especially in a rainy year. Make sure your peonies have good air circulation, are in well-drained soil, and receiving sunlight. In this case, it could also be caused by Botrytis paeoniae, which only infects peonies. 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. 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. Botrytis blight. What Causes Peony Bud Blast? Powdery Mildew? This disease generally appears in spring or early summer when the shoots of affected herbaceous paeonies wilt and turn brown for no apparent reason. Phytophthora Blight. 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. Eventually, if left untreated, botrytis will … 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. 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. Botrytis Blight? 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. 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.