Detailed Explanation of Pollution-Free Cultivation Techniques for Cauliflower

I. Variety selection. Choose varieties with strong stress resistance, wide adaptability and good market quality. For spring cultivation, choose varieties such as 'Holland Spring Early', 'Swiss Snowball' and 'Snow Peak'; for autumn cultivation, choose varieties such as 'White Peak', 'Japan Snow Mountain' and 'Holland Snowball'.
II. Raising strong seedlings:
1. Seedling raising method: According to the cultivation season and method, seedlings can be raised in cold frames, plastic arched sheds, solar greenhouses or open fields. Open-field seedling raising should have rainproof, insect-proof and shading facilities.
2. Seed quantity: 50-100 kg of seed per mu.
3. Seed treatment: Soak the seeds in 50°C warm water for 20 minutes while stirring constantly, then continue soaking at room temperature for 3-4 hours; or treat the seeds with 50% thiram wettable powder.
4. Germination acceleration: Remove the soaked seeds, wash them clean, air-dry them slightly, wrap them in a damp cloth, and place them at 20-25°C to germinate, rinsing once a day with clean water; sow when 60% of the seeds have sprouted.
5. Seedbed preparation: (1) Bed soil mixing. Select fertile garden soil that has not grown cruciferous vegetables for the past 3 years and thoroughly decomposed, sieved barnyard manure, mix them evenly in a 2:1 ratio, and add 1 kg of NPK compound fertilizer per cubic meter. Spread the bed soil into the seedbed to a thickness of 10-12 cm. (2) Bed soil disinfection. Mix 50% carbendazim wettable powder and 50% thiram wettable powder in a 1:1 ratio, or mix 25% metalaxyl wettable powder and 70% mancozeb wettable powder in a 9:1 ratio, use 8-10 g of the mixture per cubic meter, mix with 4-5 kg of sieved fine soil; at sowing, spread 2/3 on the bed surface and cover the seeds with the remaining 1/3.
III. Sowing. For early spring plastic arched sheds, sow in mid-to-late November; for open-field spring crops, sow from late December to early January; for open-field autumn crops, sow in mid-to-late June; for autumn delayed cultivation, sow in early-to-mid July. Water thoroughly to saturate the bottom soil; after the water infiltrates, cover with a layer of fine soil (or medicated soil), evenly broadcast the seeds on the bed surface, and cover with fine soil (medicated soil) 0.6-0.8 cm thick. For open-field seedling raising in summer and autumn, dry seeds can also be sown.
IV. Seedling stage management:
1. Temperature management: From sowing to full emergence, the suitable daytime temperature (℃) is 20-22°C and the suitable nighttime temperature is 15-18°C; from full emergence to pricking out, the suitable daytime temperature is 16-20°C and the suitable nighttime temperature is 8-12°C; from pricking out to seedling recovery, the suitable daytime temperature is 18-22°C and the suitable nighttime temperature is 12-15°C; from seedling recovery to 10 days before planting, the suitable daytime temperature is 15-18°C and the suitable nighttime temperature is 6°C; from 10 days before planting to planting, the suitable daytime temperature is 5-8°C and the suitable nighttime temperature is 4-6°C.
2. Thinning: Thin 1-2 times before pricking out, with a seedling spacing of 2-3 cm, removing diseased, weak and off-type seedlings, and cover with soil once after thinning.
3. Pricking out: When the seedlings have 3 true leaves and 1 heart leaf, prick out at a row and plant spacing of 10 cm on the pricking-out bed by opening furrows and planting seedlings in water, or prick out directly into 10 cm × 10 cm nutrition pots; after seedling recovery, hoe and loosen the soil 2-3 times; do not water if the bed soil is not dry; when watering, use small amounts or spray water; water thoroughly 7 days before planting, lift and hold the seedlings 1-2 days later, and carry out low-temperature hardening; for open-field seedling raising in summer and autumn, if the temperature is too high, methods such as watering and shading can be used to cool down; prevent the bed soil from becoming too dry, and at the same time prevent rainstorms from washing away the seedbed, and drain accumulated water from the seedbed in time. After pricking out, provide appropriate shading, and if conditions permit, cover with nylon mesh to prevent insects.
4. Strong seedling standard: The plant is robust, 12 cm tall, with 6-7 leaves, thick leaves, a well-developed root system and no pests or diseases.
V. Preparation before planting:
1. Land preparation and fertilization: The preceding crop is a non-cruciferous vegetable. For open-field cultivation, use level beds; for protected cultivation, semi-high beds can also be used. Apply fertilizer in combination with land preparation: 5000 kg of high-quality decomposed barnyard manure, 9 kg of urea, 75 kg of superphosphate and 12 kg of potassium sulfate per mu.
2. Insect prevention and disinfection in sheds and greenhouses. (1) Install insect-proof nets to block insects. Seal the ventilation openings of the shed or greenhouse with 20-30 mesh nylon gauze to prevent aphids from entering. (2) Lay aphid-repellent film. Cover with silver-gray plastic film to repel aphids. (3) Disinfection of sheds and greenhouses. Use 2-3 kg of sulfur powder plus 0.25 kg of 80% dichlorvos emulsifiable concentrate per mu, mix with sawdust, pile it in separate heaps, ignite, seal for 24 hours, ventilate until there is no odor in the shed or greenhouse, and then plant.
VI. Planting: 1. Planting period: For early spring plastic arched sheds, mid-to-late February to early March; for open-field spring crops, late March to early April; for open-field autumn crops, late July to early August; for autumn delayed cultivation with temporary planting, mid-to-late August. 2. Method: Open furrows or dig holes according to the required row and plant spacing, plant seedlings in water, or water after earthing up. 3. Density: For early-maturing varieties, 2700-4000 plants per mu, with a row and plant spacing of 50-60 × 33-40 cm; for mid-to-late maturing varieties, 1500-2700 plants per mu, with a row and plant spacing of 60-70 × 40-60 cm.
VII. Management after planting: 1. Early growth stage (from seedling recovery to rosette stage): Water to help seedling recovery 4-5 days after planting, then combine with cultivating and earthing up 2-3 times. Keep the soil alternating between dry and moist; after watering twice, start seedling squatting: 7-10 days for early and mid-maturing varieties, and 10-12 days for late-maturing varieties. After seedling squatting ends, apply 3 kg of urea per mu as a top dressing combined with watering. The suitable temperature in the shed or greenhouse is 15-20°C. 2. Mid and late growth stages (curd formation stage): Water according to the principle of keeping the soil moist. When the curd diameter is 3-4 cm, apply 6 kg of urea per mu as a top dressing combined with watering; for mid-to-late maturing varieties, add 1 more top dressing. When the curd diameter is 8-10 cm, tie or fold the leaves to cover the curd to keep it white. The suitable temperature in the shed or greenhouse is 15-20°C. For autumn delayed cultivation, promptly cover the shed with film or carry out temporary planting storage according to weather changes.
VIII. Pest and disease control. The use of each pesticide variety must strictly comply with the pre-harvest interval.
1. Physical control: Yellow sticky boards can be used to trap and kill aphids and whiteflies. Use rectangular cardboard boards of 60 × 20 cm, coat them with yellow paint, then coat with a layer of machine oil, and hang them in the field, 30-40 boards per mu; when the yellow boards are covered with aphids, whiteflies and other pests, coat them with another layer of machine oil; silver-gray plastic film strips can also be hung to repel aphids.
2. Chemical control of diseases: In protected cultivation, priority should be given to dust and fumigation methods; in dry and clear weather, spray control can also be used, taking care to rotate pesticides and mix them reasonably.
(1) Downy mildew. Use 110-180 g of 45% chlorothalonil smoke agent per mu, fumigate in a closed shed in the evening, once every 7 days, for 3-4 consecutive times; after finding central diseased plants, spray with 150-200 times dilution of 40% fosetyl-aluminium wettable powder, or 600-800 times dilution of 72% propamocarb (Previcur) aqueous solution, or 500 times dilution of 75% chlorothalonil wettable powder, alternating and rotating use, once every 7-10 days, for 2-3 consecutive sprays.
(2) Black spot. In the early stage of disease, use 500-600 times dilution of 75% chlorothalonil wettable powder, or 1500 times dilution of 50% iprodione wettable powder, once every 7-10 days, for 2-3 consecutive sprays.
(3) Black rot. In the early stage of disease, use 600 times dilution of 14% copper ammonia complex aqueous solution, or 1500 times dilution of 77% copper hydroxide wettable powder, or 4000 times dilution of 72% agricultural streptomycin sulfate soluble powder, once every 7-10 days, for 2-3 consecutive sprays.
(4) Gray mold. In the early stage of disease, use 200-250 g of 10% procymidone smoke agent per mu, or spray 6.5% dimethirimol ultra-fine dust or 5% kasugamycin-copper dust, 1 kg per mu; after disease onset, spray with 2000 times dilution of 50% procymidone wettable powder, or 1000-1500 times dilution of 50% iprodione wettable powder, or 600 times dilution of 40% carbendazim-sulfur suspension, once every 7-10 days, for 2-3 consecutive sprays.
(5) Black leg. In the early stage of disease, spray with 600 times dilution of 60% carbendazim-thiram wettable powder, or 500-600 times dilution of 40% carbendazim-sulfur suspension, or 600 times dilution of 70% chlorothalonil wettable powder, once every 9 days, for 1-2 consecutive sprays.
(6) Bacterial black spot. For the application method, see black rot.
3. Chemical control of insect pests:
(1) Cabbage caterpillar. At the peak of egg hatching, choose 200 times dilution of BT emulsion, or spray 2500 times dilution of 5% chlorfluazuron emulsifiable concentrate; before the larvae reach the 2nd instar, spray 5000 times dilution of 2.5% cyhalothrin emulsifiable concentrate, or 1000 times dilution of 10% bifenthrin (cypermethrin) emulsifiable concentrate, or 1000 times dilution of 40% phoxim emulsifiable concentrate.
(2) Diamondback moth. At the peak of egg hatching, use 5% fipronil suspension concentrate, 17-34 mL per mu, diluted with 50-75 L of water, or 2000 times dilution of 5% chlorfluazuron emulsifiable concentrate, or before the larvae reach the 2nd instar, spray 3000 times dilution of 1.8% abamectin emulsifiable concentrate, or 200 times dilution of BT emulsion. The above pesticides should be rotated and used alternately; never use a single type of pesticide continuously year after year.
(3) Aphids. Use 2000-3000 times dilution of 50% pirimicarb wettable powder, or 1500 times dilution of 10% imidacloprid wettable powder, once every 6-7 days, for 2-3 consecutive sprays. Adding an appropriate amount of spreader-sticker improves the effect.
(4) Beet armyworm. At the peak of egg hatching, use 2500-3000 times dilution of 5% chlorfluazuron emulsifiable concentrate, or before the larvae reach the 3rd instar, spray 1000 times dilution of 52.25% chlorpyrifos-cypermethrin emulsifiable concentrate; apply on clear evenings, and all day on cloudy days.
IX. Harvesting. It is suitable to harvest when the curd has fully grown and is compact, with a smooth surface and basal flower branches slightly loose; it can also be harvested in time according to market demand.