Technical guidance on the production of sweet potatoes for fresh food and processing in 2017

Sweet potato is an important grain and industrial raw material crop in China. In recent years, the consumption structure of sweet potato has changed obviously, the proportion of feeding has decreased, and the proportion of fresh food and processing has gradually increased. According to the National planting structure Adjustment Plan (2016-2020), the focus of potato crop adjustment is to expand the area, optimize the structure, process and transform, improve quality and increase efficiency. In order to make effective use of light and heat resources in various places and give full play to the advantages of sweet potato for fresh food and processing in structural adjustment, stable grain income, transformation and value-added, technical guidance on the production of sweet potato for fresh food and processing in 2017 has been formulated.

(1) to select improved varieties and cultivate healthy seedlings. Excellent varieties are selected according to resource endowment, climatic conditions and planting use. It was found that the infected virus disease should be removed in time, the seedling transportation should be strictly quarantined, and the annual continuous use of field potato seedlings should be avoided in the southern potato area, so as to prevent the spread of sweet potato SPVD virus disease and leaf roll virus disease. Strengthen seedbed management, cultivate healthy seedlings, and select clean fields without virus pollution to produce seed potatoes.

(2) reasonable close planting and optimizing the planting system. In accordance with local conditions to determine a reasonable planting density, fresh sweet potato should pay attention to improve the rate of commercial sweet potato. In the northern potato area, the fresh edible spring potato can be sowed late and planted densely, with a density of 3500-4000 plants per mu, and the fresh edible summer potato can be planted early and planted in the first and middle of June with a density of 4000-4500 plants per mu. The northern part of the southern potato region is dominated by summer potatoes, and the southern part can be planted all the year round, with a planting density of about 3000 plants per mu. To strengthen crop rotation, we can rotate crops such as peanuts, corn, wheat and millet, reduce diseases and insect pests and continuous cropping obstacles, and increase production and efficiency. Large-scale planting of sweet potato for starch is advocated, and the planting density can be reduced appropriately.

(3) strengthen the field management and optimize the group structure. In the early stage after planting, we focus on promoting growth, early seedling emergence and early ridge closure; in the middle stage, we control the growth of stems and leaves, focusing on the establishment of reasonable population structure, and if necessary, we can carry out chemical control according to the growth of aboveground stems and leaves; in the middle and later stages, we can focus on promoting the expansion of potato tubers, and according to the actual situation, we can apply 100 grams of potassium dihydrogen phosphate per mu according to the actual situation, and pay attention to waterlogging prevention in the later growth stage. Film mulching cultivation and other technical measures can be used to improve yield and benefit in the potato areas of the north and the middle and lower reaches of the Yangtze River. Film mulching is generally not recommended in arid and barren hills and mountains.

(4) fertilizing scientifically to promote high and stable yield. Rational fertilization should adhere to the principle of giving priority to base fertilizer, supplemented by topdressing, giving priority to organic fertilizer, supplemented by chemical fertilizer, giving priority to the application of potash fertilizer and supplemented by phosphate fertilizer. When the soil total nitrogen content is less than 0.08% and the available nitrogen content is less than 20-30 mg / kg, 5 kg-20 kg per mu of pure nitrogen is applied as base fertilizer; when the available nitrogen is higher than 80 mg / kg, no nitrogen fertilizer can be applied. When the content of available phosphorus is less than 20 mg / kg, 5 kg of pure phosphorus is applied as base fertilizer per mu, and phosphate fertilizer is not applied when the content of available phosphorus is higher than 50 mg. When the content of available potassium is less than 30 mg / kg, 20 kg per mu of pure potassium is applied; when the content of available potassium is 30-100 mg / kg, 10-20 kg per mu of pure potassium is applied; if the content of available potassium is more than 150 mg / kg, no potassium fertilizer can be applied.

(5) giving priority to prevention and comprehensive prevention and control of diseases and pests. For diseases without effective control such as root rot and potato blast, disease-resistant varieties should be selected and planted disease-free, so as to strengthen planting prevention and control and restrain bacterial infection. For black spot, choose a strong seedling with a height of 25-30 cm, soak the 10 cm part of the seedling base in 50% carbendazim wettable powder 500-800 times or 50% methyl thiophanate 300-500 times for 8-10 minutes. For underground pests, the measures of physical control and chemical control are adopted to carry out targeted prevention and control so as to improve the rate of commercial potato. For example, setting up black light to trap and kill adults in the field, selecting chemical pesticides with high efficiency and low toxicity and other measures to prevent and control grubs and golden needles. Comprehensive measures should be taken to prevent the harm of ants in the southern potato area.