Seven precautions for girdling jujube trees that growers must remember
I think everyone is very familiar with jujube trees, and many people should have witnessed the growth process of jujubes. As the saying goes, “Eat three jujubes a day, and youth will never fade”, so jujubes are deeply loved by everyone. Do not underestimate those individual jujubes; they actually contain great nutritional value!
Seven precautions for girdling when planting jujube trees
Jujube trees suffer severe flower and fruit drop, which seriously affects increases in yield. Girdling, also called "jiashu" or "kaijia", is a simple and effective measure to increase fruit set, promote ripening, and improve quality. When applying this technique, the following seven points should be noted:
1. Time: For varieties with severe flower drop, the suitable period is generally the early full-bloom stage (flower quantity 30%-50%); for varieties with severe fruit drop, girdling should be done after full bloom and before the peak fruit-drop period. Girdling is best done at noon on a clear day.
2. Position: Generally, it is carried out on the main trunk 10-20cm above the ground. In subsequent years, girdling can gradually be done upward at intervals of 3-5cm each year until the first main branch. For vigorous branches, it can be done 5-10cm from the base of the branch.
3. Width: Generally 0.3-0.7cm. When girdling, the coarse bark at the girdling site should be scraped off. The upper cut should slope downward and the lower cut should slope upward. The cut opening must connect to form a closed ring, with no remaining bark and no rough edges; otherwise, the effect will be poor. Vigorous trees should have a wider cut, while weak and small trees should have a narrower one. Generally, the cut heals 25-30 days after girdling.
4. Depth: Use a sharp knife to reach the xylem, but do not injure the xylem. Only remove the phloem layer and leave the cambium, so that nutrients above ground accumulate to meet the nutritional needs of flowering and fruiting. If an axe is used, use a sharp axe to cut the main trunk horizontally, with consistent depth, reaching the xylem. Young trees are cut once a year, with 3 rings cut at one time in a plum-blossom three-point pattern. Trees in full fruit stage are cut once every 3 days, for a total of 3-4 times, until fruit set occurs.
5. Cut opening: After girdling, the wound should be coated with insecticide to prevent insects, and wrapped with paper or plastic film to prevent sunscald, air-drying, or damage by people and livestock.
6. Target trees: Generally, it is done only on large trees (7 years old or older, or trunk diameter greater than 10cm), vigorous trees, and vigorous branches. It is best not to use it on small or weak trees. For young vigorous trees (4-7 years old), 1-2 branches or trunks can be girdled in rotation each year, with a width of 0.2-0.3cm according to branch thickness, and 2-3 rings cut (without removing the bark layer).
7. Management: If fruit set is excessive after girdling, fruit thinning may be done appropriately, and fertilizer and water management should be strengthened to ensure sufficient nutrition and prevent pre-harvest fruit drop and tree decline. When fruit set is heavy, branches should be propped to prevent branch breakage and splitting.
Planting time for jujube trees
The planting period for jujube trees is divided into autumn planting and spring planting. In areas without severe winter cold, where the average January temperature is not lower than -8°C, autumn planting can be carried out, that is, planting after the jujube tree sheds its leaves and before the soil freezes. In jujube-producing areas south of the Yangtze River in China, winters are relatively warm and soil moisture is good. The wounds on jujube roots can heal in the same year of planting, and some new roots will develop. They can then grow promptly the following spring. Therefore, autumn planting of jujube trees has a high survival rate and also produces good growth.
Jujube is also called jujube fruit, Chinese date, spiny jujube, and guanzao. It grows in mountainous areas, hills, or plains below 1700 meters above sea level. It is widely cultivated. This species originated in China and is often cultivated in Asia, Europe, and the Americas. Jujube contains rich vitamin C and vitamin P. Besides being eaten fresh, it can often be made into preserved fruits and candied fruits such as candied jujube, red jujube, smoked jujube, black jujube, wine jujube, and yazao, and can also be made into jujube paste, jujube flour, jujube wine, jujube vinegar, etc., serving as raw materials for the food industry.
In most jujube-producing areas north of the Yangtze River in China, winters are severe, ground temperatures are low, and the soil may even freeze. After autumn planting of jujube seedlings, the root system has weak water absorption, while drought and frequent wind often increase transpiration from the aboveground parts, causing severe water loss in branches, wrinkled and dried bark, and even seedling death. In recent years, when planting jujube trees in autumn in some areas, measures such as watering after planting, watering before freezing, and watering again the following spring to promote bud break have significantly increased the survival rate of autumn-planted jujube seedlings.
However, most northern regions still adopt spring planting. Experiments on jujube planting at different times by relevant departments in Hebei Province show that jujube trees planted about 10 days before bud break have a survival rate significantly higher than those planted at other times. Planting at this time results in fewer cases of bud loss and bud regression, and stronger growth vigor. The reason is that during this period, seedling transpiration is low, stored nutrients in the plant are abundant, the root system recovers quickly after planting, and the survival rate is high.
Growth habits of jujube trees
Jujube trees grow in mountainous areas, hills, or plains below 1700 meters above sea level. They are a thermophilic fruit tree. The average annual temperature in production areas is about 15°C. During bud break, the temperature needs to be 13-15°C; during shoot growth and leaf expansion, 17°C; during flowering and fruit set, 22-25°C; and during fruit ripening, 18-22°C. Jujube trees are relatively drought-tolerant and waterlogging-tolerant, but the flowering period requires relatively high air humidity; otherwise, pollination and fruit set are unfavorable. In addition, jujube has strong light requirements and is relatively sensitive to light response. It has strong adaptability to soil and tolerates poor soil and salinity-alkalinity. However, it is afraid of wind, so wind gaps should be avoided when establishing an orchard.
Jujube cultivation techniques
1. Orchard site selection: Jujube trees have relatively strong adaptability and do not have strict requirements for soil conditions, so wasteland and saline-alkali land can be fully used for cultivation in various places. However, in order to achieve relatively high economic benefits and produce high-quality, pollution-free products, it is best to choose orchard sites where air, water sources, soil, and other environments are not polluted, the terrain is flat and open, drainage conditions are good, soil permeability is strong, aeration is good, the groundwater level is relatively high, and the soil is fertile. When planting jujube trees in mountainous and hilly areas, sunny slopes with deep soil layers should be selected; shady slopes are not suitable for planting.
2. Planting varieties: There are many varieties of jujube trees. A high-quality variety must have good tree vigor, strong resistance to diseases and pests, fruit that resists cracking, good fruit shape, good fruit color, high nutrient content, and good taste. At present, excellent varieties used for drying include Jinsifeng, Jinsimi, Wuhehong, Wuhe No. 1, Wuhe No. 3, and Zanhuang Dazao. Among early-maturing varieties, excellent varieties for fresh eating include Zaocuiwang, Jingwei Xianzao, and Zaoshu Lizao; excellent varieties for processing include Lizao and Zanhuang Dazao. Late-maturing varieties are mainly used for fresh eating; high-quality varieties include Jingwei Daxuezao and Dongzao. New and special varieties include Mopanzao and Hul-uzao with peculiar fruit shapes, and Tailihong and Longxuzao with peculiar tree shapes.
3. Cultivation models: The first is dwarf and close-planting cultivation, mainly suitable for varieties with early fruiting and small tree size, with row spacing preferably 2m×3m or 3m×2m. The second is intercropping cultivation, mainly suitable for varieties with medium or larger tree size and later fruiting, with row spacing 8-10m and plant spacing 3-5m. Other crops can be interplanted between trees in the early stage.
4. Cultivation time: Jujube trees can be cultivated throughout the entire dormant period from leaf fall to the following year before bud break, and this is divided into spring planting and autumn planting. According to many years of cultivation experience, with 2-year-old and older root-sucker seedlings, spring planting with immediate thorough watering can easily achieve a survival rate above 90%, while autumn planting can hardly exceed a 90% survival rate even if watered after planting. However, after autumn planting, the survival rate can still reach above 70% even without watering, while if spring planting is not watered, the survival rate is clearly lower than that of autumn planting.
When planting jujube trees, there are still many points to pay attention to. It is not something that will grow healthily and end up full of fruit just by planting it casually. If you want jujube trees to grow healthily and produce jujubes, you must carefully tend and care for them.