Detailed Tutorial on the Latest Cultivation Techniques for Napa Cabbage
Cabbage originated in northern China and is a leafy vegetable of the genus Brassica in the family Brassicaceae, usually referring to napa cabbage; it also includes bok choy and the cultivated variety of cabbage known as head cabbage, i.e. “round cabbage” or “Western cabbage”. It was introduced to the south, and is now cultivated throughout both northern and southern regions. Cabbage has broad adaptability and can be cultivated in all four seasons, but is grown most in autumn and winter. This article focuses on autumn and winter cabbage cultivation techniques.
Selection of Garden Plot and Variety
Although napa cabbage has strong adaptability, to achieve high yield, high quality and high efficiency, one must select a plot with loose soil, deep soil layer, good aeration, medium fertility, no water accumulation, convenient drainage and irrigation, no “three wastes” pollution, and convenient transportation. At the same time, according to different cultivation seasons, select varieties with high yield, high quality and good market sales. For summer and autumn, generally select varieties tolerant to high temperature and humid heat such as “Gaokang No. 2”, “Xingdian No. 1”, “83—1”, etc.; for winter and spring, varieties such as “Xiaoza 56” and “Zao Huangbai” can be selected.
Planting Season
Napa cabbage can be sown and cultivated all year round in Wenshan Prefecture, but August—October is best; for spring napa cabbage sown in February—March, plastic film mulching cultivation is used; for summer and autumn sowing in April—July, attention should be paid to selecting heat-tolerant, disease-resistant varieties; for sowing from November—the following January, insulated cultivation should be carried out. At the same time, according to market demand and variety market trends, select varieties that are well-suited to the market.
Land Preparation and Ridge Formation
After the previous crop is harvested, plow and sun the soil in time, harrow fine, remove weeds, and level the land. Whether winter sowing for spring harvest or summer and autumn sowing, high ridges should be made, with a ridge width of 2 m, a ditch depth of 0.3 m, and a ditch width of 0.3 m.
Sowing
1. Seed treatment. Before sowing, soak the seeds in 55°C warm water for 15 minutes, then air-dry and dress the seeds with carbendazim, or dress with 0.3%—0.4% thiram, chlorothalonil or ridomil. Alternatively, sunning the seeds for 1—2 days before sowing can prevent some diseases.
2. Soil disinfection and seedling-stage prevention. In continuous cropping land or areas with frequent disease, 70% dexon powder can be mixed evenly with 20 times dry fine soil and some insecticides (such as chlorpyrifos, deltamethrin, etc.), and spread into the sowing holes. At the seedling stage, spray with 75% chlorothalonil wettable powder at 500 times dilution or 20% Kuaike wettable powder at 900—1000 times dilution for prevention.
3. Sowing method and density. Direct seeding is adopted; after ridge formation, make holes and sow in spots according to variety characteristics and soil fertility. Density should be reasonably set according to the characteristics of the variety. For example, “83—1” generally has a plant-row spacing of 40×40 cm, with about 4,000 holes per mu; the Xiaoza series has a plant-row spacing of 35×35 cm, with about 5,000 holes per mu; sow 5—6 plump seeds per hole, cover the holes with fine manure soil after sowing, and keep the soil moist.
4. Apply sufficient base fertilizer. Mainly organic fertilizer, supplemented by chemical fertilizer; apply 3,000 kg of high-quality decomposed farmyard manure per mu plus 40—80 kg of compound fertilizer, compost them together, and apply once into the holes as base fertilizer.
Field Management
1. Timely thinning and final singling of seedlings. For plastic film mulching, after emergence, timely break the film to expose the seedlings, and seal and press the film openings with fine soil. When the seedlings grow to 2—3 leaves, thin out weak, diseased and mixed seedlings, leaving 2—3 plants per hole; when there are 4—5 true leaves, combine with the second thinning to carry out final singling, keeping 1 healthy seedling.
2. Intertillage and weeding. Combine intertillage and weeding with thinning and final singling; carry out shallow intertillage; in the rainy season, increase the number of intertillage operations to prevent soil compaction.
3. Irrigation and drainage. In winter and spring, drought makes water shortage likely, so watering should be done in a timely manner to keep the soil moist, especially during the head-forming stage, where moderate watering should be paid even more attention. In summer and autumn, with high temperature and abundant rain, attention should be paid to clearing ditches after rain, earthing up, and draining waterlogging, promptly removing accumulated water in the ditches to prevent root rot and dead seedlings and invasion by pathogens. Due to the particularity of our prefecture's geographical location, intermittent drought can also occur in summer and autumn. Because high temperatures cause large evaporation, timely watering should also be carried out, using early and late watering to lower soil temperature and prevent high-temperature damage.
4. Topdressing. Generally, the two key topdressings should be grasped: the rosette stage and before head formation. This is the key to ensuring high yield of napa cabbage. At this time, napa cabbage is in a rapid growth period and requires increased topdressing amounts, mainly nitrogen fertilizer, supplemented with phosphorus and potassium fertilizer, or regular application of diluted human, livestock and poultry manure. The specific topdressing measures are: the first, after final singling, use 1,000 kg of decomposed clear manure water; the second, at the rosette stage, use 1,000 kg of decomposed clear manure water per mu plus 20 kg of urea; the third is the key topdressing period, namely the beginning of head formation, using 1,000 kg of decomposed clear manure water per mu plus 20 kg of urea. In the middle of head formation, spray 1:250 times monopotassium phosphate to enhance plant resistance, produce vegetables with excellent appearance and internal quality, and increase commodity value.
Pest and Disease Control
Pest and disease control adopts the policy of prevention first and integrated control. When pests and diseases are found in the field, select biological pesticides and efficient, low-toxicity, targeted pesticides for control.
1. Viral disease
Viral disease mainly includes cucumber mosaic virus, tobacco mosaic virus, turnip mosaic virus, and viruses transmitted by aphids.
Symptoms: When disease occurs at the seedling stage, the heart leaves show clear veins and vein chlorosis, then produce uneven dark green mottling or mosaic; in the adult plant stage, early-infected leaves are severely wrinkled, hard and brittle, often with many small brown spots, and brown slightly sunken necrotic streak spots on the main veins of the leaf underside; the plant is obviously dwarfed and deformed, and does not form heads or forms loose heads.
Main control measures: select disease-resistant varieties; adjust vegetable layout, carry out reasonable crop rotation, and promptly remove diseased plants when found; sow early at the appropriate time to avoid high temperature and the peak season of aphids; aphid control at the seedling stage is very important, and every possible effort should be made to control virus-transmitting aphids; at the early stage of disease, spray with Virus No. 1 emulsion at 500 times dilution, or Virus No. 2 emulsion at 1000 times dilution, or 20% Kuaike wettable powder at 900—1000 times dilution, or 3.95% Bingdubike at 600—800 times dilution for control.
2. Soft rot
Soft rot is a bacterial disease, occurring from the rosette stage to the heading stage. The pathogen overwinters in diseased plant residues and in the bodies of pests, and spreads through rainwater, irrigation water, contaminated fertilizer, and insects.
Symptoms: There are commonly 3 types: outer leaves appear wilted; at the rosette stage, the plant can be seen wilting at noon on sunny days, but recovering in the morning and evening; after lasting several days, the outer leaves of the diseased plant lie flat on the ground, the heart or head is exposed, and the pith tissue at the petiole stem or root stem rots; the pathogen invades through wounds at the leaf base, forming a water-soaked infiltration area, which gradually expands and turns light grayish brown, with the diseased tissue becoming slimy and soft-rotted; the pathogen invades through wounds at the leaf base, forming a water-soaked infiltration area, which gradually expands and turns light grayish brown, with the diseased tissue becoming slimy and soft-rotted; the pathogen invades through wounds on the petiole or outer leaf edges, or at the top of the head, causing rot. Under dry conditions, the rotted diseased leaves gradually lose water and dry out in the sun, becoming thin-paper-like and clinging tightly to the head. The diseased and rotted areas all produce a hydrogen sulfide stench, which is an important feature of this disease.
Main control measures: as far as possible, choose fields with previous crops of wheat, rice, or legumes for planting cabbage, and avoid continuous cropping with Solanaceae, cucurbits and other Brassicaceae vegetables; clear the land and plow early to promote decomposition of diseased residues; adopt deep-ditch and high-bed planting; select disease-resistant varieties; sow at the appropriate time; treat seeds with chemicals; spray streptomycin sulfate or 72% agricultural streptomycin soluble powder at 3000—4000 times dilution, or 47% Kasugamycin-copper wettable powder at 700—750 times dilution. Spray once every 10 days, for 3 consecutive sprays.
3. Black spot
Black spot is a fungal disease. The pathogen mainly overwinters as mycelium on diseased plants and seeds, and the following year produces spores that enter through stomata or directly penetrate the epidermis.
Symptoms: It mainly harms cotyledons, true leaves, leaf blades and petioles. When leaves are infected, nearly circular chlorotic spots first appear, then gradually expand, with edges from light yellow to dark brown; after a few days the spots enlarge and have obvious concentric rings; some spots have a yellow halo, and perforate under high temperature and high humidity.
Main control measures: select disease-resistant varieties, disinfect seeds, eliminate diseased plant residues and weeds, apply sufficient base fertilizer, increase phosphorus and potassium fertilizer, and improve plant disease resistance. When diseased plants are found, promptly spray 75% chlorothalonil wettable powder at 500—600 times dilution, or 64% Sandofan wettable powder at 500 times dilution, or 58% metalaxyl-mancozeb wettable powder at 500 times dilution for control.
4. Napa cabbage tipburn
Napa cabbage tipburn is a physiological disease, mostly occurring during the head-forming stage and storage period. The causes of the disease are mostly improper application of chemical fertilizers, saline-alkali soil, poor irrigation water quality, dry weather, improper cultivation management and other factors.
Symptoms: The appearance of the napa cabbage head is normal, but after peeling open the head, some leaves can be seen turning dry and yellow from the leaf edges, with the leaf mesophyll becoming dry-paper-like. In severe cases, it can gradually develop toward the center, losing commodity value and edible value.
Main control measures: select disease-resistant varieties; strengthen cultivation management (increase organic fertilizer, pay attention to crop rotation, rationally apply nitrogen fertilizer, increase phosphorus and potassium fertilizer); increase calcium fertilizer; spray “Napa Cabbage Tipburn Control Feng” at the seedling stage, rosette stage or head-forming stage respectively for control.
5. Aphids
Aphids harm the undersides of vegetable leaves or the tender shoots and leaves of seed plants, and transmit viral diseases. Main control measures: use 50% pirimicarb wettable powder at 2000—3000 times dilution, or 40% dimethoate at 1000—2000 times dilution for control.
6. Cabbage caterpillars, striped flea beetles and underground pests
Cabbage caterpillars, striped flea beetles and underground pests are controlled with deltamethrin at 2000 times dilution, or 50% parathion emulsion at 1000 times dilution.
7. Diamondback moth
Diamondback moth is controlled with 5% fipronil suspension concentrate at 50—100 mL per mu mixed with 50 kg of water; or 5% chlorfluazuron emulsion at 2000 times dilution, 5% cascade at 2000 times dilution, or 5% lufenuron emulsion at 2000 times dilution. Diamondback moth is phototactic; during the adult occurrence period, set up one black light lamp every 10 mu to kill adults and reduce the insect source.
8. Wild slugs (mole crickets)
Wild slugs are mollusks, shaped like snails, with a degenerated shell; their bodies can secrete mucus, often leaving silvery-white traces after crawling, and they are very harmful to vegetables. Wild slugs hide by day and come out at night, causing damage at dusk. Place tiles, vegetable leaves, or bundles of vegetable stalks or branches in the middle of the field; after the sun comes out, they often hide among them and can be gathered and killed. Use snail bait or fenbutatin oxide, calcium arsenate and other drugs mixed with rice bran, bean bran, green grass, etc., to make poisoned bait for killing. Use 0.5 kg of 5% snail bait mixed with 5 kg of fine soil and scatter in the field in the evening; use 0.7 kg of 6% Mita granules per mu or 1—2 kg of 3% Miewoling granules, crush and mix with 5—7.5 kg of fine soil, and scatter in the rows near the roots of affected plants on a warm evening when the soil surface is dry; after 2—3 days, wild slugs that contact the pesticide secrete large amounts of mucus and die.
Harvest
When napa cabbage heads are firm, it indicates that growth has matured, and it should be harvested and marketed in time. The buffer period from maturity to harvest is 7—10 days; if it exceeds 10 days, it will form broken heads and bolting, or cause leaf loss and rotting, reducing commodity value in mild cases and leading to total crop failure in severe cases.