Greetings, Human Cultivators. We, the members of the *Paeonia* genus, are generally resilient beings, but we are not immune to the ailments that plague the plant world. Our vitality and magnificent blooms depend on your keen eye to identify and address these issues promptly. Here is a detailed account from our perspective.
This fungal menace, caused by *Botrytis cinerea* and *Botrytis paeoniae*, is our most frequent adversary. It thrives in the cool, wet conditions of spring. You will first notice our young shoots turning black and rotting at the base before they can even properly emerge from your soil. If the infection strikes later, it causes our flower buds to turn brown and abort, often covered in a fuzzy gray mold. On our mature leaves, it creates large, dark brown, leathery patches. This fungus overwinters on our plant debris and in your soil, waiting for the perfect conditions to attack.
Do not be fooled by the informal name; this disease, caused by the fungus *Cladosporium paeoniae*, is a significant stressor. It manifests as glossy, purplish-brown or chocolate-brown spots on our upper leaf surfaces. As these spots enlarge, they often coalesce into large, irregular blotches, making our foliage appear scorched. This weakens us considerably, as it severely reduces our ability to photosynthesize and prepare for the next growing season. The pathogen also survives the winter on our fallen leaves and stems.
These are among the most serious threats we face. Two primary fungi, *Verticillium dahliae* and *Sclerotinia sclerotiorum*, cause similar but distinct wilting symptoms. They invade our vascular systems through our roots, blocking the flow of water and nutrients. You will see our stems wilt and die suddenly, often with one stem affected at a time. The base of an infected stem may show a brown or black decay. *Verticillium* wilt causes a brown discoloration of the vascular tissue under the bark, while *Sclerotinia* may produce white, cottony fungal growth and hard black resting bodies called sclerotia.
Your intervention is crucial for our recovery and long-term health. Please adopt these practices. First, practice impeccable sanitation. In fall, after our tops have died back, cut our stems down to ground level and remove all foliage and debris from the garden. Do not compost this material; destroy it. This removes the primary overwintering sites for these fungi. Second, ensure we are planted in well-draining soil and that you water us at the base, avoiding splashing water onto our leaves and stems. Provide adequate spacing between us and other plants to promote good air circulation. If fungal issues are a recurring problem, you may apply a preventative fungicide spray as our new shoots emerge in early spring. For wilts, there are no effective chemical controls; the only solution is to dig up and destroy the entire infected plant to prevent the disease from spreading to our neighbors through the soil.
