Peony diseases are common and can significantly affect the health and beauty of the plants. Here are some of the most prevalent ones:
1. **Leaf Spot (Erythema):** This disease starts with small, purple-brown spots on the leaves that gradually expand into irregular, larger lesions. Over time, these spots may develop a distinct ring-like pattern, and mold may appear as the infection progresses.
2. **Gray Mold:** Gray mold affects the leaves, stems, and flowers. On the leaves, it causes brown, round spots with irregular edges. When humidity is high, gray mold develops on the affected areas. On flowers, it creates brown patterns, and the buds may fail to open or rot and turn brown after damage.
3. **Brown Spot:** Initially, small purple-brown spots appear on the leaves, which then grow into larger, light to dark brown lesions with ring-like patterns.
4. **Rust:** During flowering, yellow-brown spots appear on the leaves. These spots soon develop into orange-yellow pustules. When they rupture, they release orange-yellow spores. The underside of the leaves may also show fine, wooly hairs.
5. **Anthracnose:** This disease shows up as round or irregular yellow-brown spots on the leaves. The edges of the spots are dark brown, and black dots may appear in the center.
6. **White Peony Disease:** This disease primarily affects the root neck area. In the early stages, white mycelium forms on the surface, and water-soaked brown spots appear. Later, brown sclerotia develop, causing the above-ground parts of the plant to weaken and eventually die.
To prevent and control these diseases, it is recommended to dip the roots in a 70% thiophanate solution diluted at 500 times for 10 minutes before planting. Once the disease occurs, you can water the roots with a 50% dextroxycholine solution diluted at 400 times or spray the plants with a 50% carbendazim solution diluted at 800 times. For rust, a 300-times dilution of diniconazole sodium is particularly effective.
In terms of pests, peonies are not heavily affected, but common pests include scale insects, cockroaches, and leaf roller moths. Root and neck damage from larvae is more frequent and severe. To manage underground pests, apply 5% phoxim granules (2 kg per acre) evenly on the soil surface and mix them into the top 20 cm of soil. This method has proven to be highly effective in controlling pest infestations.
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