Squatting disease and blight are two serious threats to the seedling stage of Qiuyan solanaceous vegetables. If pesticide control is not implemented in a timely manner, severe seedling death can occur, leading to reduced yield quality and significant losses for farmers. These diseases not only affect plant health but also impact overall productivity and profitability.
First, let’s understand the main symptoms. 1. **Damping-off disease**, caused by fungi, typically affects seedlings from germination up to the stage when they have 3–4 true leaves. Before emergence, infected seeds may rot, and after germination, the seedlings show water-soaked lesions at the base of the stem. These lesions rapidly expand, then narrow into a linear shape, soften, and fold. The young leaves remain green, but the plant eventually collapses.
2. **Blight disease**, also fungal in nature, usually occurs later during the seedling stage. Initially, dark brown oval spots appear at the base of the stems. Affected plants wilt during the day but recover at night. As the disease progresses, the lesions expand, and the plants become stunted and eventually die.
Second, here are effective prevention and treatment methods:
1. **Seed disinfection**: Treat seeds with a new high-fat membrane before sowing. This helps protect against underground pests, isolate virus infections, and does not interfere with germination or swelling. It enhances respiration and increases germination rates.
2. **Greenhouse hygiene**: Regularly remove diseased plants, old leaves, and weeds. Clean up dead leaves, roots, and other debris to eliminate pathogen sources. Spraying tree guards and destroying infected materials can significantly reduce the spread of disease.
3. **Improved management**: Seedlings are vulnerable to extreme weather like heavy rain or intense sunlight, which weakens them and lowers their resistance. Strengthening management practices—such as proper watering, ventilation, and using a new high-fat film—can help retain soil moisture, prevent excessive transpiration, and improve seedling resilience.
4. **Physical regulation**: Applying strong-stem sprays during the growing season can promote thicker stems and healthier foliage. This not only enhances the plant’s natural flavor but also improves its ability to withstand environmental stress and reduces the need for chemical inputs.
5. **Pesticide application**: It is advisable to use low-toxic, non-residual **bio-pesticides**. In early stages of infection, a mixture of 72.2% Plectranthus water agent diluted 400 times and new high-fat film diluted 600 times (2–3 liters per square meter) works well. Alternatively, 15% carbaryl water agent diluted 450 times can be used. For mixed infections, a combination of 72.2% Plectranthus water agent (800 times), 50% thiram WP (800 times), and new high-fat film (600 times) can enhance effectiveness.
By following these measures, farmers can significantly reduce the risk of disease, ensure healthier crops, and maintain sustainable agricultural practices.
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