In spring, temperatures gradually rise, rainfall increases, and pests and diseases begin to emerge. At the same time, some sensitive seedlings start to grow. Therefore, it's essential to intensify nursery management during this period. Here are four key points to consider:
Early spring weather is highly unpredictable, with significant temperature fluctuations. Especially during rainy or snowy days, frost can occur unexpectedly, which may damage young seedlings. To prevent this, frost protection measures must be implemented. For seedlings grown in protected areas, large greenhouses should be covered before cold spells. If needed, additional coverings like straw mats can be placed over the greenhouse film. Valuable seedlings can be placed under smaller arch-shaped covers to maintain warmth. On sunny days, these covers can be removed to allow sunlight exposure. However, on clear days when temperatures rise quickly, attention must be paid to controlling greenhouse temperatures to avoid overheating. In open nurseries, wind barriers should be set up in the north to protect against strong cold waves.
Spring often brings wet and muddy conditions due to rain and snow. Poor drainage in low-lying areas can lead to waterlogged soil, which lowers soil temperature and reduces oxygen availability, hindering root growth. In severe cases, this can cause seedling death and delay recovery. To prevent this, trenching should be done around the nursery before the rainy season, and existing drainage ditches should be cleaned. If no drainage system exists, new ditches should be dug and existing ones deepened. This helps drain excess water and filter out standing water, ensuring the nursery remains dry after rain. For drought-resistant species like acacia, locust, and clove trees, timely drainage is crucial to avoid high groundwater levels. Using a shallow, well-aerated soil mix combined with ash application can improve moisture retention and promote healthy seedling growth.
In early spring, some seedlings can be sown or cut. When applying base fertilizer, organic material is recommended. Without it, seedlings may suffer from root damage as temperatures rise. For newly emerging seedlings, it's important to avoid over-concentrated fertilizers. Diluted human or animal manure is best, as concentrated chemical fertilizers can burn roots and harm the plants.
Common diseases in spring include damping-off, blight, root rot, and anthracnose. Damping-off and blight are particularly prevalent, spreading rapidly as temperatures and humidity increase. These fungal diseases can kill many seedlings, especially since they're young and vulnerable. The optimal soil temperature for Pythium is 12°C to 20°C, while Rhizoctonia and Fusarium thrive around 20°C. High humidity (10%–100%) accelerates their spread. To manage these issues: 1) Improve drainage by deepening or creating new ditches to lower the groundwater level and reduce moisture; 2) Remove and destroy any infected seedlings immediately, and sprinkle lime powder around the affected area to prevent re-infection; 3) Spray the nursery every 10–15 days with 0.5%–1% Bordeaux mixture (50–75 kg per acre) or a 65% zinc sulfate solution (500 times diluted) to create a protective layer that prevents bacterial infection and kills pathogens.
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