Key Technical Points for Green Food Sweet Potato Cultivation

I. Selection of Production Site for Green Food Sweet Potato

The production base for green food sweet potato should be established in areas with fresh air, pure water, uncontaminated soil and a sound agricultural ecological environment; well-drained, deep soil with loose structure, rich in organic matter, good water and fertilizer retention, and a pH of 6.0-7.5 sandy loam or loam, where Convolvulaceae plants have not been grown for 2-3 years, and the plot must be free of any diseases. Environmental conditions must comply with the Ministry of Agriculture's "Environmental Technical Conditions for Green Food Production Areas" (NY/T391-2000).

II. Cultivating Disease-Free Strong Seedlings

1. Selection of Disease-Resistant High-Quality Varieties

For starch types, select Jishu 98 and virus-free Luxuan No.1; for fresh-eating types, select Xinong 431, Zhenghong 2A, Meiying No.1 and other varieties.

2. Careful Selection and Disinfection of Seed Potatoes

Strictly select seed potatoes that are free of pests and diseases, freeze damage and waterlogging damage, with tuber weight of 150-250 g (separated by size); use Nongkang 120, Zhongshengmycin, etc. to control black spot disease.

3. Seedling Raising Methods, Timing and Seed Quantity

Use heated brick bed (huokang) with insulating film for seedling raising, which has good heat preservation and moisture retention effects; start on the heated bed before Qingming; for fresh-eating types, use 35 kg of seed potatoes per mu of field; for starch types, use 30 kg of seed potatoes per mu of field.

4. Seedbed Management

① Water: Water thoroughly once before placing on the heated bed to ensure sufficient water before seed potatoes sprout, then water once after each pulling of seedlings.

② Temperature: Raise the germination temperature (the highest return temperature after the fire is stopped) from 38°C to 41-42°C; when the temperature drops to 35-36°C, start the fire again; stop the fire 2-3 days before pulling seedlings.

③ Air: After covering the heated bed with insulating film, provide convective ventilation every 3-5 days to prevent rot from oxygen deficiency.

III. Land Preparation and Ridging

Start ridging after the soil thaws in late March; ridge spacing should be uniform, ridges straight, ridge surface flat, ridge soil loose, soil crumbly, no missed cultivation in the ridge center, ridge width 50 cm.

IV. Fertilization

Apply 2500 kg of organic fertilizer per mu that has undergone high-temperature fermentation and decomposition along with ridging,

10 kg of potassium sulfate, 3 kg of urea, 5 kg of ammonium phosphate.

V. Field Planting

1. Timing: For plastic film mulching cultivation, in mid-to-late April; for open-field planting, generally in early May.

2. Planting density: Generally 4500-5000 plants/mu for dry thin land or short-vine varieties, 4000-4500 plants/mu for fertile land or long-vine varieties.

VI. Field Management

1. Early Stage Management

Check seedlings and replant missing ones, early intertillage, weeding (from survival stage to before ridge closure, intertill 2 times), control underground pests; timely topping (when main vine is 50-60 cm long), remove unexpanded tender buds, then top the group, which helps control excessive vine growth in the later stage.

2. Mid-Stage Management

Prevent drought and drain waterlogging; when soil is dry, water lightly. In rainy seasons, drain promptly to ensure no water accumulation in the field; control excessively vigorous fields; when leaf area index exceeds 5.0 for a long period, lift vines without turning them; foliar spray fertilizer to prevent premature aging; if leaf area index is less than 4.0, spray 1% urea mixed with 0.2-0.4% monopotassium phosphate solution 1-2 times.

3. Late Stage Management

Prevent premature aging, control excessive growth, lift vines without turning them, spray 0.4% monopotassium phosphate solution 2 times; prevent drought and drain waterlogging, and timely control leaf-eating pests.

VII. Integrated Pest and Disease Control Techniques for Green Food Sweet Potato

Give priority to agricultural measures, through a series of measures including selecting disease-resistant and insect-resistant varieties, cultivating strong seedlings, strengthening cultivation management, intertillage and weeding, deep plowing and sun-drying soil in autumn, cleaning the field, crop rotation, intercropping and relay cropping, to achieve the effect of controlling pests, diseases and weeds.

1. Agricultural measures: ① Healthy potatoes and healthy seedlings, crop rotation, targeting major pest and disease control objects; clean fertilizer, clean water, strict management, promote healthy growth of sweet potato plants, suppress the occurrence of pests and diseases; ② Reasonable dense planting, clean the field, reduce the number of pest and disease sources; ③ Timely handling of diseased potatoes and diseased plants. For disease prevention, monitor the disease center in the field, promptly remove diseased plants. During storage and seedling raising, deeply bury diseased potato and diseased plant residues when found.

2. Biological Control

① Control of sweet potato stem nematode disease: Use 1.8% abamectin emulsifiable concentrate at 3000-5000 times dilution for root irrigation (400-500 ml per plant).

② Control of aphids and underground pests such as wireworms, cutworms, and white grubs: Use 0.38% matrine emulsifiable concentrate at 300-500 times dilution for spraying (to control aphids) or root irrigation (to control underground pests).

③ Control of white grubs, etc.: Use 2% Beauveria bassiana powder at 2 kg/mu, broadcast before ridging or apply in holes at planting, cover with soil after application, strictly prevent sun exposure.

VIII. Harvesting

Begin harvest when soil temperature drops to 12-15°C; for storage of fresh potatoes and seed potatoes, complete harvest before "Frost's Descent"; for fresh-eating potatoes, for early market, they can also be harvested early as long as the tubers are fully swollen. Xu Xiuyan