The success of high-quality grape seedlings largely depends on effective summer and autumn management. With over 20 years of experience in cultivating grape seedlings, the Institute has established a large-scale nursery covering a million vines. This extensive experience has led to refined techniques for managing grape seedlings during critical growth periods. Here’s a detailed guide to help growers achieve better results.
**1. Shoot Management**
- **Pruning:** By mid-July, cuttings typically reach 40–50 cm in height, often with multiple shoots. In dense nurseries, it's essential to remove weaker shoots to encourage the growth of stronger ones. Only one strong shoot should be left per plant.
- **Tip Pinching:** When shoots reach about 50 cm, the top 10–15 cm is removed. Any side shoots that emerge after this should be eliminated, except for the one at the top. When the main shoot has 5–6 leaves, leave 2–3 leaves and pinch off the rest. All new shoots that appear on these secondary tips must also be removed.
- **Supporting Growth:** For certain premium varieties, shoots may need to be trained to grow vertically. Two methods are commonly used: either inserting bamboo poles between rows every 3–4 meters and securing them with ropes, or using individual bamboo stakes for each plant. A crossbar at the top helps prevent damage from wind or accidental knocks.
**2. Soil and Fertilizer Management**
- **Fertilization:** Two main approaches are used—top-dressing and foliar spraying. Urea is commonly applied when seedlings have 7–8 leaves, at a rate of 15–20 kg per acre. This can be repeated every 15 days, usually three times. Foliar sprays include 0.5% urea in summer and 0.3% potassium dihydrogen phosphate in autumn, applied twice each season.
- **Watering:** Before new shoots emerge, water every 7 days. Once they reach 10–20 cm, watering should occur every 15 days. After reaching 30–40 cm, watering can be reduced to every 20 days. Avoid watering if it rains heavily or if the soil is already moist. When seedlings reach 50 cm, water should be controlled. If plants remain in the nursery until winter, a final watering is necessary before cold weather sets in.
- **Weeding:** Most nurseries use plastic mulch, which reduces the need for mechanical weeding. However, manual removal of weeds is still required around the base after each watering to prevent competition for nutrients.
**3. Pest and Disease Control**
Pest and disease management is crucial for producing healthy, virus-free seedlings. Key diseases include downy mildew and black rot, while pests such as cotton bollworms, beet armyworms, and grape hawk moths require attention. Integrated pest management through spraying is recommended.
- Begin spraying when seedlings have 7–8 leaves, using a 500-fold solution of carbendazim (50%) and 600–800-fold solution of mancozeb (80%) after two weeks. After transplanting, apply a 1:0.7:200 Bordeaux mixture. If downy mildew appears, use 600-fold Kepo or 80% chlorothalonil at 300–500 times dilution.
- In autumn, switch to a 1:1:180 or 1:1.5:180 Bordeaux mixture. During pest seasons, add insecticides like dichlorvos (1000–1500 times) for hawk moths or Longwei 1 (1000–1500 times) for bollworms. Spraying should be done in the late afternoon to avoid high temperatures.
**4. Variety Purity Management**
Each grape variety has unique characteristics. Once new shoots have 7–8 leaves, their identity becomes clear. Any hybrid plants must be removed immediately. In large nurseries, mark different varieties with bamboo sticks or plastic ropes. Maintain a detailed record of each variety’s location and quantity to prevent mixing. Even a small amount of mixed variety can reduce quality and cause future losses.
**5. Timely Removal**
After the fall season, do not remove seedlings immediately. Allow the roots to store nutrients. It is best to transplant them before or after the "Minor Snow" period, ensuring they are ready for planting in the next growing season.
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