Cultivation technology

Seedling cultivation method

Sweet potato seedlings need to be cultivated 2 months before transplanting and planting, that is, spring potatoes start to breed in late January, and autumn potatoes start in late January. Seedlings are raised in mid-to-late June, and early winter potatoes are raised in early to mid-August. The seedlings can be raised in one time or propagated in batches. Selection and breeding of seedlings, purification and rejuvenation are carried out every year. Seeds should be selected in fields free of viral diseases and scab disease and of the same variety. Choose medium-sized seed potatoes with long, even shapes, no ridges, straight skin, smooth skin, and no spots or scars for planting. Soak the seed potatoes in 1.0% copper sulfate solution or 2% sodium hydroxide solution for 5 to 10 minutes. You can also soak the seed potatoes for 2 hours with Bt, Beauveria bassiana and other biological agents allowed for organic production. It is best to use gauze greenhouses for breeding under insect-free conditions. Virus-free vaccine.

Adequate base fertilizer should be applied to the seedbed. Generally, 500 to 1000kg of self-retting organic fertilizer and 50kg of mineral potassium and magnesium fertilizer are applied per 667 square meters. Use lime sulfur mixture or lime to disinfect the seedbed or shed before sowing.

Seedling management

During the sweet potato seedling cultivation period, top-dress fertilizer according to the seedling condition. The fertilizer should be organically certified or bio-organic fertilizer approved by the organic certification agency (NPK total nutrient content ≥ 6 %, organic matter content ≥40%), the total amount of top dressing during the seedling period is generally 250kg per 667 square meters. In the first "red bud" stage, thin fertilizer and water are generally applied; when the seedlings are 10 to 13 cm tall, the second top dressing can be carried out. After each application of fertilizer, the seedlings should be washed with clean water to prevent fertilizer from adhering to the seedlings and causing seedling burning.

The soil cultivation can be carried out in 2 to 3 times. When the seedling height is about 10cm, the first soil cultivation can be carried out. The second soil cultivation can be carried out every 7 days, and the final soil cultivation is 3 to 5cm. To cultivate the soil, it is best to mix fertile loose fine soil with burnt marl or decomposed compost and spread it evenly into the seedbed. Soil cultivation can be combined with the application of liquid fertilizer. The soil should be cultivated first and then fertilized, so that the soil and the base of the seedlings are closely combined to facilitate early and multiple new roots.

After planting, spray Bt and other organic production-licensed biological inoculants and 300 times tea bran water once every 15 days, sprinkle plant ash once; and place sex hormone traps around the seedbed or outside the nursery shed. .

In seedbed management, measures such as heat preservation, moisture retention, and ventilation should also be taken, focusing on temperature. Before the seedlings emerge, cover them with straw curtains at night and keep the bed temperature at 25-35°C. After emergence, the temperature should be controlled at 20-25°C to prevent the seedlings from burning due to high temperature. If the temperature inside the film exceeds 30°C, ventilation and heat dissipation should be carried out in time to prevent the seedlings from burning. When the cold wave comes, insulation work should be done well.

Seed potatoes are generally not watered before emergence to facilitate high temperature germination, disease prevention and emergence. If the seedbed is too dry, use a sprayer to spray clean water on the seedbed. After emergence, pay attention to the humidity of the seedbed. When the seedbed turns white, water it in time to moisten the bed soil and sprinkle thin fertilizer water to promote the growth of potato seedlings; when the seedbed is too wet, remove the film in time for ventilation. ?

Soil preparation and ridging

Choose plots of Brassicaceae, Liliaceae, and Gramineae crops for the previous crop, preferably leguminous crops, and manually remove the field after the previous crop is harvested. Weeds, dead leaves. Use machines or animal power to deeply plow the soil and dry the soil. At the same time, apply 500kg of bio-organic fertilizer, 300kg of plant ash, 50kg of mineral potassium and magnesium fertilizer, and 25kg of phosphate rock powder every 667 square meters. ?[6]?. The base fertilizer should be applied about 30cm deep, and the distance between the base fertilizer and the seedlings should be more than 16cm.

Riding specifications: For spring and autumn planting, the ridge width is 100cm and the furrow is 30cm high; for winter planting, the ridge width is 120cm and the furrow is 120cm wide, and the ridge height is 25-30cm. It requires thick ridges and narrow and deep furrows. ?

Fertilizer and water management

The requirements of sweet potatoes for the three elements nitrogen, phosphorus and potassium vary depending on the growth period. Nitrogen fertilizer is absorbed more during the growth period of stems and leaves, and less is absorbed during the period of root expansion; phosphorus fertilizer is absorbed less during the middle growth period of stems and leaves, and more is absorbed during the period of root expansion; while potassium fertilizer is absorbed more than nitrogen and phosphorus from planting to harvest. The root expansion period is more significant. Therefore, sweet potato fertilization should be based on this characteristic, N:P:K=5:6:20. It is best to use soil testing and formula fertilization technology.

It is forbidden to use any chemical fertilizers in the organic planting of sweet potatoes. The application of base fertilizer is the main one. Generally, the amount of base fertilizer accounts for 60% to 80% of the total fertilizer amount. The base fertilizer is applied in combination with land preparation and ridge removal. After the transplanted seedlings are alive, apply biogas slurry or fully decomposed thin manure once as a fertilizer for seedlings. The second time is during the sweet potato fruiting period, that is, about 60 days after planting in spring and autumn, and a top dressing of potato fertilizer once about 70 days after planting in winter.

Potassium fertilizer is mainly used for potato fertilization. Generally, 500kg of homemade organic fertilizer (or organic certified organic fertilizer), 250kg of plant ash or 25kg of mineral potassium and magnesium fertilizer are applied per 667 square meters. The application method is generally to use a plow to break both sides of the ridge, or use a small hoe to create a small ditch at the waist of the ridge, then mix the fertilizer and probiotics thoroughly and apply them in strips. Watering should be done once after application to promote the fertilizer effect as soon as possible. . At the same time, after fertilizing, artificial weeding can be combined with soil cultivation.

After the sweet potatoes are watered with seedling water when planting, they will begin to branch and drag vines 30 to 40 days after planting, and the water demand will increase. If there is a drought at this time, water should be watered in time. You can take Furrow irrigation method, but the irrigation amount cannot exceed 1/2 of the ridge height. Overall, it is advisable to keep the soil basically moist during water management. In case of rainy days, waterlogging should be drained in time to prevent the accumulation of water from causing the potato seedlings to grow excessively, causing only firewood roots but no potatoes.

Pest and disease control

Disease control

Viral diseases, leaf spot, scab, sweet potato blast, sweet potato vine cutting disease, sweet potato soft rot, etc.

Disease prevention and control methods

The first is to use virus-free seedlings to disinfect the seedlings; the second is to carry out chemical control according to different diseases.

Control and prevention of physiological diseases: Due to factors such as soil deficiency, physiological deficiency, poor environment (too dry, too wet, sunburn, high temperature, low temperature), deficiency diseases, Sunburn, aging, weakness, wilting and other physiological diseases.

Prevention and control methods: Choose resistant varieties or insensitive varieties; choose robust varieties with strong growth potential; water appropriately to keep the surface and plants dry; maintain appropriate density; maintain crop rotation in planting plots. Reduction occurs.

For non-infectious diseases, use sulfur and copper preparations to control them. For bacterial diseases, such as soft rot, water appropriately and at the same time to keep the surface and plants dry. Fungal diseases, such as downy mildew, rust and other soil-borne diseases, can be controlled by adopting film mulching and drip irrigation measures to keep the environment dry.

Viral diseases can be controlled by controlling aphids.

Pest Control

Stem borers, horn moths, leaf rollers, leaf beetles, small beetles, wireworms, chafers, mole crickets, cutworms, Spodoptera litura, aphids and white powder Lice etc.

1. Crop rotation. The paddy field implements a rotation of paddy and drought. Rice is planted in the early crop and sweet potatoes are planted in autumn or late rice is planted in winter. Or aquatic vegetables are planted in spring and summer and sweet potatoes are planted in autumn and winter.

2. Adopt tissue culture and virus-free seedling cultivation method.

3. Lighting kills insects. Install one frequency vibration insect trap lamp every 20,000 square meters.

4. Comprehensive control measures for underground pests such as weevils, cutworms, mole crickets, wireworms, and leaf beetles. Spray 500 times probiotic liquid every 15 days after planting; spray Beauveria bassiana or tobacco leaf (tobacco stem) water once 2 to 3 months after planting; the spraying time should be staggered by 15 days; every 667 square meters Place 15 to 20 small weevil sex attractant traps.

5. Prevention and control of stem borer. Spray azadirachtin or rotenone once 20 days after planting to control sweet potato stem borer, spray once every 10 days, and spray 2 to 3 times continuously.

Reference: Baidu Encyclopedia Sweet Potato