Peony diseases can significantly affect the health and beauty of these ornamental plants. Here are some common peony diseases along with their symptoms and control methods:
1. **Leaf Spot (Erythema):** This disease starts with small, purple-brown spots on the leaves that gradually grow into irregular, larger spots. These spots often develop a ring-like pattern, and as the disease progresses, moldy material may appear on the affected areas.
2. **Botrytis Blight (Gray Mold):** Gray mold commonly affects the leaves, stems, and flowers. It causes brown, round spots on the leaves with irregular patterns. In wet conditions, a gray mold develops on these spots. On the flowers, a brown pattern appears, and the buds may fail to open or rot, turning brown after damage.
3. **Brown Leaf Spot:** Initially, small purple-brown spots appear on the leaves. As the disease progresses, these spots expand into light brown or even dark brown rings.
4. **Powdery Mildew (Rust):** During flowering, yellow-brown spots appear on the leaves, which soon develop into orange-yellow pustules. When these pustules rupture, they release orange-yellow spores. A fine, woolly growth may also be seen on the underside of the leaves.
5. **Anthracnose:** The leaves show round or irregular yellow-brown depressions with dark brown edges and black dots in the center.
6. **White Root Rot (White Peony Disease):** This disease affects the root neck area. At first, white mycelium appears on the surface of the roots and neck, followed by water-soaked brown spots. Later, brown sclerotia form, causing the above-ground parts of the plant to weaken and eventually die.
To prevent these diseases, it is recommended to dip the roots in a 70% thiophanate solution diluted at 500 times for 10 minutes before planting. If an infection occurs, you can water the roots with a 50% dextrocam solution diluted at 400 times or spray the plants with a 50% carbendazim solution diluted at 800 times. For rust, applying a 300-times dilution of mancozeb is particularly effective.
In terms of pests, peonies are not heavily affected, but some common pests include scale insects, cockroaches, and leaf roller moths. Damage to the roots and neck is especially common. To control underground pests like larvae, applying 5% phoxim granules (2 kg per acre) evenly on the soil surface and then incorporating them into the top 20 cm of soil can provide effective control. Regular monitoring and early intervention are key to maintaining healthy peony plants.
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