The Latest Lettuce Cultivation Techniques and Methods Tutorial

Lettuce (celtuce) is a 1-2 year crop of the Asteraceae family, Lactuca genus, with shallow and dense roots mostly distributed within the 20-30 cm soil layer. Lettuce prefers a cool climate; short-day conditions and low temperatures favor its growth and development, while long-day conditions and high temperatures easily cause bolting and flowering. Lettuce tissue is crisp and tender and high in water content, and the entire growth period requires a uniform and fairly sufficient water supply.

Planting Season

Lettuce has wide adaptability. According to market demand, different varieties can be selected to achieve staggered sowing and balanced year-round production and supply. In Tonghai (main season), sowing is mainly in autumn and winter, with harvest in winter and spring; the main varieties are Yubang No. 1, No. 5, Round Leaf No. 1, Four-Season Round Leaf hybrid, etc. In summer, Large Flower Leaf and Bamboo Leaf Green are the main varieties.

Land Preparation and Fertilization

Choose soil that is loose, well-drained, rich in organic matter, and with strong water and fertilizer retention as suitable. Deep plow and sun the land, apply 2-3 tons of decomposed farmyard manure per mu, sun the clods for 7-10 days, then finely prepare the land, forming beds 1.8-1.9 m wide; flat beds are used for main-season planting and raised beds for off-season planting.

Sowing

After the seedling bed is prepared, sow the seeds directly on the seedling bed, water, then drench the seedling bed with 4.5% Baishida emulsifiable concentrate at 3000 times dilution and 5% Kungfu emulsifiable concentrate at 3000 times dilution to prevent underground pests. Each mu of field requires 15-20 sq m of seedling bed; generally, 25-30 g of seed is used per mu of field, covered with shade netting, then compacted.

Generally, transplant at a spacing of 32×35 cm between plants and rows, planting 4800-5200 plants per mu. When transplanting, discard seedlings whose stems have already swollen, to avoid early bolting.

Field Management

Water promptly after transplanting. After the transplants have taken, drench with ammonium bicarbonate at 8-10 kg per mu plus 10 kg of calcium superphosphate diluted in water. Afterward, control water and fertilizer and strengthen cultivation; from the rosette stage until the leaves close over the rows, water and topdress, applying 10-15 kg of urea and 5 kg of potassium sulfate per mu, and thereafter alternate between drying and moistening. When the stem begins to thicken, apply the third topdressing, with 50 kg of ternary compound fertilizer, 10 kg of potassium sulfate, and 15 kg of urea per mu applied in holes.

Pest and Disease Control

1. Diseases

① Downy mildew: Downy mildew is especially severe on lettuce and easily occurs under high temperature and high humidity. Apply metalaxyl-mancozeb or Sandofan 20 days after transplanting. In the early stage of disease, downy mildew can be controlled with 687.5 g/L Infinito suspension concentrate at 1000-1500 times dilution, 66.8% Mieduoke wettable powder at 1000-1500 times dilution, or 77.2% propamocarb aqueous solution at 1000-1700 times dilution.

② Leaf spot and brown spot: Can be controlled with 75% chlorothalonil (Daconil) wettable powder at 1500-2000 times dilution; 10% Score (difenoconazole) water-dispersible granules at 3000-3500 times dilution.

③ Sclerotinia rot: In recent years, sclerotinia rot has also caused fairly serious damage; it is a low-temperature, high-humidity disease. When the temperature is around 5-15°C and the relative humidity is above 85%, it favors the occurrence and invasion of the pathogen. It can be controlled with 50% iprodione wettable powder at 1500-2000 times dilution, 50% procymidone wettable powder at 2000-2500 times dilution, thiophanate-methyl, etc. In addition, viral diseases can be controlled with Duxiao, Haopu, etc.

2. Insect pests

① Aphids: 50% imidacloprid emulsifiable concentrate at 3500-4000 times dilution.

② Leafminers: For adults, 1.8% abamectin emulsifiable concentrate at 4000-5000 times dilution can be used; for larvae, 75% Qianke (cyromazine) wettable powder at 4500-5000 times dilution can be used for control.

Harvest

When the top of the main stem of the lettuce is level with the tip of the highest leaf, it can be harvested. At this time, the tender stem has reached full length, is crisp and tender, and of good quality; remove the old leaves and it is ready for market.