Detailed Explanation of Key Points for Virus-Free Sweet Potato Cultivation Techniques

Virus-free sweet potatoes differ from ordinary sweet potato varieties, and their cultivation techniques also differ. The cultivation techniques are introduced as follows:

1. Ridging and early planting. Virus-free sweet potatoes have strong drought tolerance and vigorous growth. After the wheat harvest, ridges should be made as early as possible to strive for early planting.

2. Formula fertilization. For dry and infertile land, apply 5000 kg of farmyard manure, 30-40 kg of ammonium bicarbonate, 15-20 kg of potassium sulfate, and 40-50 kg of superphosphate per mu; for medium to above-medium fertility fields, apply 3000-4000 kg of farmyard manure, 20-30 kg of ammonium bicarbonate, 20 kg of potassium sulfate, and 30 kg of superphosphate per mu. In addition to applying sufficient base fertilizer, it is also necessary to apply hole fertilizer, seedling-promoting fertilizer, tuber-promoting fertilizer, and later-stage foliar topdressing, etc.

3. Reasonable close planting. Virus-free sweet potatoes have the characteristics of uniform growth and rapid tuber expansion, so reasonable close planting should be adopted in cultivation. For summer sweet potatoes, 3500-4000 plants per mu is appropriate.

4. Field management. 3-5 days after planting, timely check for missing plants and fill gaps. After the seedlings recover, cultivate in time to promote early seedling growth (generally 2-3 cultivations are appropriate). In the middle and later stages of growth, do well in drought resistance, drainage, and pest and disease control. In addition, virus-free sweet potatoes are best cultivated in isolation. In areas without isolation conditions, attention should be paid to controlling aphids, and mixed planting of virus-free potatoes with ordinary potatoes should be eliminated to strictly prevent virus back-transmission, so as not to shorten the service life of virus-free sweet potato varieties. Other field management measures are the same as for ordinary sweet potatoes.

5. Timely harvest. Special care should be taken during harvest and storage of virus-free sweet potatoes to prevent variety mixing. In addition, because of their good sprouting ability, temperature should be well controlled during storage to prevent premature sprouting. The cellar storage temperature should be controlled at 9°C-15°C, and a certain humidity should be maintained.

Virus-free treated sweet potato varieties can be continuously planted for 3-4 years in production. If the time is longer, virus accumulation will occur, affecting yield. Therefore, virus-free treatment must be carried out again.