Management of High-yield Tree shape of Young Citrus trees

The management goal of young citrus trees is to promote the growth of new shoots and the emergence of robust shoots, accelerate the order of branches, form a plump crown as soon as possible, establish a solid skeleton, and lay a good foundation for high and stable yield. In order to achieve this goal, the management technical measures should be as follows:

1. Timely and appropriate amount of fertilization

Young citrus trees are in the vegetative growth stage, with large root and shoot growth, and stop growing late. Fertilization should focus on meeting the nutrient needs of tree growth and shoot emergence. The times and amount of fertilization should be determined according to the growth potential and growth characteristics of young trees. The principles of diligent, thin and key fertilization should be grasped in the fertilization of young trees. Young trees can shoot 3 times per year for 4 times, and the growth is large. In addition, due to the infiltration and loss of fertilizer in the soil, it is necessary to apply fertilizer 9 times a year. The key point is to apply fast-acting fertilizer before germination and growing period of spring, summer and autumn shoots. Give priority to nitrogen fertilizer, combined with phosphorus and potassium fertilizer. The ratio of nitrogen, phosphorus and potassium was 5:1:3. The tree is strong with little or no application. If the tree is weak, the times and amount of fertilization should be increased appropriately. Organic fertilizer is mainly applied in late autumn or early winter, with appropriate application of phosphorus and potassium fertilizer. Organic fertilizer 20-50kg, compound fertilizer 0.5-1kg, calcium magnesium phosphate or calcium 1-2kg were applied to each plant. It can improve the physical and chemical properties of soil and enhance the activity of enzymes in soil. With the rapid expansion of the crown, the amount of fertilizer application should be gradually increased.

2. Cultivate plump crown skeleton.

Reasonable shaping and pruning can cultivate the tree shape with firm skeleton, uniform branches, plump crown and three-dimensional fruit. The shaping of young trees should be determined according to the planting density, the level of cultivation techniques, topography, varieties and other factors. Citrus trees generally have round head shape, pagoda shape, natural happy shape, hedge shape, and Ya shape. According to the factors of cultivated varieties and management level in Jianshui area, the shape of young citrus trees is generally round head, pagoda or natural happy shape. In the shaping and pruning of young trees, in addition to reasonably setting the trunk and cultivating a solid crown skeleton, the most important thing is to coring the new shoots, especially the summer shoots, to promote branches, increase the number of branches, and quickly form a plump crown to achieve the purpose of early high yield. When the growth of summer and autumn shoots reached 20-30 cm and the terminal buds were not lignified, 2-3 buds at the top of the extended branches outside the crown were removed, which played a faster role in the expansion of the crown. Overdense and overlapping branches in the canopy should be erased or cut off as soon as possible to reduce nutrient consumption.

3. Water management

In areas with prominent drought in winter and spring, water should be irrigated once before spring shoots sprout to meet the water needs for new shoots sprouting and growing. Secondly, combined with fertilization, irrigation or application of water and fertilizer. Stagnant water is most avoided in citrus orchards. Rain Water should timely eliminate stagnant water and lower the groundwater level below the root distribution layer, so as not to cause rotten roots and leaves of citrus trees and affect their growth. Water management should generally grasp the principles of spring irrigation, summer drainage, autumn control and appropriate amount in winter.

4. Pest control

The common diseases and insect pests in citrus producing areas in Jianshui County are: leaf miner, red spider, orange aphid, Phoenix butterfly, sagittal scale, brown soft scale, anthracnose, scab, powdery mildew and so on. In addition to strengthening cultivation management and enhancing tree resistance, stone sulfur mixture or sulfur gel suspension was sprayed 2-3 times in winter, once every 7-10 days, to eliminate overwintering diseases and insect pests and reduce damage index. According to the law of occurrence and development of various diseases and insect pests in the field in the growing season, chemical pesticides or biological pesticides with high efficiency, low toxicity and low price should be selected to control the disease before the peak incubation period of pest larvae. The types of pesticides should be used alternately and rotated in order to reduce drug resistance and cost, improve the effect of control, and control diseases and insect pests below the allowable level of economic damage.

5. Soil management

Young citrus trees are in a period of large growth, and the soil should be loose and fertile and free of weeds. The crops should be 50-100 cm away from the citrus trees. So that young citrus trees have a better living environment.

6. Extra-root topdressing

Combined with pest control, the leaf curtain layer was alternately sprayed with 1000 times of fruit and vegetable power, 800 times of high magnesium application and 0.3% of zinc sulfate. It can meet the absorption of nutrients in time, enhance the physiological metabolism of leaves, improve the photosynthetic rate of leaves, and achieve the effect of strong branches and green leaves.

After the careful management of the above comprehensive technical measures, even if the fixed seedlings are one-year-old seedlings, the third year can enter the fruiting period. The average yield per mu can reach 1-1.5 tons, doubling in the fourth year and 3-5 tons per mu in the fifth year.