Autumn lettuce planting techniques and field management methods
I. Land preparation and planting
The plot for planting autumn lettuce requires fertile soil with strong water and fertilizer retention capacity, and fine tillage. When plowing, apply 3-5 cubic meters of farmyard manure per mu, 30-50 kg of compound fertilizer with a high-nitrogen, low-phosphorus, medium-potassium ratio, 20-30 kg of biological bacterial fertilizer, and 200-400 grams of trace element fertilizer. After plowing and leveling the back, make flat beds. Then use a hoe to dig holes. The hole spacing (plant and row spacing) is 35-40 cm, with about 5,000 holes dug per mu. When the autumn lettuce seedlings grow to 5-6 true leaves, they can be planted. When planting, try to choose cloudy or rainy days, as this helps rapid seedling recovery and improves the survival rate. When transplanting, try to keep the seedlings upright and avoid tilting. Water promptly after planting.
II. Field management
After watering for seedling recovery, while the ground is not yet dry, hoe and loosen the soil twice, following the principle of shallow on the first pass and deep on the second. Note that when hoeing and loosening the soil, if any seedlings are tilted or fallen over, promptly earth up and straighten them, because tilted seedlings will produce curved lettuce, commonly known as "stick lettuce," which greatly reduces the marketability of the lettuce and further affects income. If there is heavy rainfall, after the rain stops and the sky clears, promptly hoe and loosen the soil again. Lettuce likes moist soil, so it should be watered appropriately to keep the soil moist. About 15 days and about 10 days after planting the lettuce, respectively, combine with watering and apply 20 kg of Cailele per mu and 20 kg of calcium ammonium nitrate plus 1 kg of potassium dihydrogen phosphate per mu.
III. Timely harvesting
If autumn lettuce is harvested too early, it affects yield and income; if harvested too late, it will become hollow and bolt. It should be harvested before bolting, when the outer leaves are level with the growing point.
IV. Pest and disease control
The main diseases of autumn lettuce are downy mildew, soft rot, black rot, and sclerotinia rot. In the early stage of disease, use 72.2% propamocarb 1000-fold solution or 70% Antaisheng 600-fold solution to spray for downy mildew control, spraying 3-4 times consecutively. Use 30% copper nitrohumate 500-fold solution or 14% copper ammonia complex aqueous solution 300-fold solution to spray for soft rot and black rot control, spraying twice consecutively at 7-10 day intervals. Use 50% vinclozolin 1000-fold solution or 50% iprodione 1000-fold solution to spray for sclerotinia rot control, spraying twice consecutively at 7-10 day intervals. The main insect pest of autumn lettuce is the American serpentine leafminer, which can be controlled by spraying 40% Wanling 1300-fold solution.