Detailed Explanation of the Causes of Fruit Cracking in Jujube Trees and Prevention Measures

In recent years, the problem of cracked jujubes has been troubling jujube growers, causing varying degrees of loss to jujube production, with losses exceeding 50% in severe cases. The problem of cracked jujubes is the most difficult problem to solve in jujube production, and deserves great attention from fruit tree researchers and jujube growers. Through years of practice, the author has taken targeted measures based on the causes of cracked jujubes, which can effectively solve the problem of cracked jujubes. The summary is as follows for the reference of fruit tree researchers and jujube growers.

1. Causes of cracked jujubes

Cause one: Years of applying chemical fertilizers and drought cause soil compaction, and the lack of soluble calcium in the soil that can be absorbed by jujube tree roots leads to cracked jujubes. China has a history of more than 30 years of chemical fertilizer application, and the amount used has increased year by year. The main types are ammonium bicarbonate, superphosphate, diammonium phosphate, ammonium sulfate, potassium sulfate, potassium chloride, etc. After these chemical fertilizers are applied to the soil, the carbonate ions, phosphate ions, sulfate ions and chloride ions in the fertilizers combine with calcium ions in the soil to form water-insoluble calcium carbonate, calcium phosphate, calcium sulfate and calcium chloride, reducing the soluble calcium in the soil and causing calcium deficiency. At present, soil in most areas of China, especially in the arid northern regions, is deficient in calcium, and soil drought is one of the causes of calcium deficiency. When the soil is dry, it is not conducive to the activity of soil microorganisms, and most of the calcium fixed in the soil can only become soluble calcium through the metabolism of microorganisms.

Cause two: The lowering of the groundwater level and uneven soil moisture cause cracked jujubes. Before the 1970s, there was basically no occurrence of cracked jujubes, mainly because the groundwater level was high at that time. Even if it did not rain and no watering was done, the jujube tree roots did not lack water, so uneven soil moisture would not occur.

2. Measures to prevent cracked jujubes

Based on the above two causes of cracked jujubes, we should consider activating calcium in the soil, supplementing calcium to the leaves, and maintaining soil moisture, and take practical and feasible measures to fundamentally prevent cracked jujubes.

1. Orchard grass mulching

Cover the area where roots are concentrated with 10-20cm thick chopped straw. If a high-density pure jujube orchard is planted, the whole orchard can be covered. The best time for grass mulching is from June to October; at this time, the temperature and humidity under the mulch are relatively high, which is conducive to the massive reproduction of soil microorganisms and helps activate calcium in the soil; in autumn, it can extend the root growth time, and in summer and winter it can reduce the soil temperature difference, which is conducive to root growth, especially the growth of surface roots. Grass mulching can maintain soil moisture well and keep soil humidity constant, thus preventing the occurrence of cracked jujubes. Long-term grass mulching will significantly increase the organic matter content in the soil. Wheat straw, wheat bran, crushed corn stalks, etc. can be selected.

2. Mulching the tree plate with plastic film

Generally, before the jujube tree sprouts, cover the ground with 1-2 meter wide plastic film along the row on both sides of the tree. This can maintain soil moisture, prevent the soil from becoming too dry, and effectively prevent cracked jujubes.

3. Using the hole-storage fertilizer and water technique

On the inner side of the vertical projection of the fruit tree, dig 4 holes with a diameter of 30-40cm and a depth of 40-50cm, and bury one grass bundle with a diameter of 20-30cm and a length of 30-40cm upright in each hole. The grass bundle is made from various crop stalks or weeds, with a height 10cm below the ground. After soaking it thoroughly with water, place it into the hole. The surroundings of the grass bundle should preferably be filled with soil mixed with biological bacterial fertilizer and organic fertilizer, then fill with water. Cover the hole with a 1 square meter plastic film, press the edges firmly with soil, insert a hole in the middle, and usually seal it with a stone to prevent water evaporation. Because the holes can store a large amount of irrigation water and rainwater, and the water infiltrates and is preserved in the deep layer, part of the root system maintains sufficient moisture and cracked jujubes are prevented.

4. Supplementing calcium to the leaves

The author used "Fangsuo Fanglie Wang" at 600 times dilution and sprayed it once each at the flowering stage, young fruit stage, fruit expansion stage, mid-growth stage and late growth stage, five times in total. After 3 years of use, it has been proven to effectively prevent the occurrence of cracked jujubes.

If the above four techniques are used in combination, the effect of preventing cracked jujubes is better.