From my perspective as a peony plant, the first sign of trouble often begins at the soil line in early spring. A fuzzy, grayish-brown mold, known to gardeners as Botrytis cinerea, attacks my young, succulent red shoots as they emerge from the ground. This fungus thrives in the cool, wet conditions of spring. The infection causes these tender shoots to wilt and collapse suddenly, as if they have been rotted at the base. It is a frightening feeling, as this attack can kill the shoot before it even has a chance to mature and produce leaves.
If the infection is not checked, the botrytis blight moves upward, traveling along my stems. You might notice dark brown, sunken lesions or cankers forming on the stems. These lesions effectively girdle me, cutting off the flow of water and nutrients to the parts of the plant above the infection. This causes the stems to wilt and the leaves to turn black and die. The leaves themselves may develop large, irregular brown spots, especially along the margins or tips. In high humidity, you will see the characteristic gray, fuzzy fungal growth on these affected areas.
The most devastating stage of this disease, from my viewpoint, is the assault on my flower buds. I work all season to produce these beautiful blooms, and botrytis blight can destroy them in a matter of days. The fungus causes the buds to turn brown and blacken, becoming dry and brittle. They either fail to open entirely or, if they do manage to open, the flowers are distorted and covered in the same fuzzy gray mold, quickly turning into a slimy, rotten mess. This is often accompanied by a complete collapse of the peduncle (the flower stalk).
To help me fight this disease, I need you to create an environment where the botrytis fungus cannot thrive. My most urgent need is for excellent air circulation around my leaves and stems. Please ensure I am not overcrowded by other plants. I also require well-draining soil; I despise having my crown and roots sitting in constant moisture. When you water me, please do so at the base in the morning so my leaves have time to dry completely before nightfall. In the fall, after my foliage has died back, it is critical that you cut my stems down to the ground and remove all leaf debris from the area. Do not compost this material, as the fungus will overwinter there. This sanitation is my best defense for a healthy emergence next spring.
