From our perspective as peony plants, the first signs of this fungal invasion, caused by the pathogen *Botrytis paeoniae*, are often subtle and easily mistaken for physical damage or environmental stress. The attack typically begins on our tender new shoots in early spring. You may notice that our emerging reddish shoots suddenly wilt and collapse, appearing as if they have been scorched. This is the fungus girdling and killing the tissue from within. As the disease progresses, small, water-soaked, dark brown or black lesions appear on our stems, leaves, and flower buds. These spots rapidly enlarge under cool, wet conditions, causing stems to soften and buckle, often at a point near the soil line.
When the fungus sets its sights on our prized blossoms, the results are particularly disheartening. Small, unopened buds may turn black and wither, never having a chance to unfurl. Larger buds might appear blighted and fail to open properly. If they do manage to open, the petals will exhibit unsightly brown spots and quickly become slimy and matted together with a fuzzy, grayish-brown mold—this is the defining sign of the pathogen sporulating. This fuzzy growth releases countless new spores into the air, ensuring the disease's spread to other parts of our structure and to neighboring plants.
Our most fervent request for treatment is preventative and cultural. *Botrytis cinerea* thrives in moisture, so your first line of defense is to keep us dry. Please ensure we are planted in a location with excellent air circulation and full sun, which helps our foliage dry quickly after dew or rain. In the fall, after our top growth has died back, it is crucial that you cut our stems down to the ground and remove all foliage and debris from the area. Do not compost this material; destroy it. This removes the fungal sclerotia (overwintering structures) from the garden, drastically reducing the source of infection for the next spring. Please also avoid mulching too early in the fall or piling mulch against our crowns, as this creates a damp, perfect environment for the fungus.
If the infection is severe or recurrent, we may require the application of a registered fungicide. This is a measure we prefer to avoid but acknowledge is sometimes necessary for our survival. At the first sign of disease in spring, you can apply a protectant fungicide containing chlorothalonil or mancozeb. For more active infections, systemic fungicides containing thiophanate-methyl or a combination of active ingredients can be more effective. It is absolutely vital that you follow the label instructions precisely, both for our health and for the safety of the surrounding environment. Always rotate between different chemical classes (FRAC groups) to prevent the botrytis from developing resistance. The best strategy is to combine chemical controls with rigorous cultural practices for a holistic approach to our well-being.
