A、Cultivation conditions of prunes
Prunes are generally planted in areas where the average annual temperature is above 9℃. In the south of the country, we use woolly peach as rootstock. In extreme weather, the minimum temperature is not lower than -22℃. Using apricot and this rootstock as rootstock, the annual minimum temperature is not lower than -28℃ and the absolute maximum temperature is 42℃. The frost-free period is more than 180 days.
Choose the area with deep soil layer and water table below 1m for afforestation. While soil texture is medium loam, light loam, sandy loam and sandy soil. Soil PH value 7~8.5, root layer depth 10~60m, total salt content 0.35% or less.
B、The varieties of prunes
There are many varieties of prunes. At present, the main varieties planted in South China are Richard Early, French Prune, Goddess, Early Moonlight, Big Rose, etc.
Prunes are self-pollinated. High fruit set rate, strong resistance to low temperature, late frost and dust hazard during flowering. We can use a single variety to build a garden. Take a multi-variety configuration. Heterogeneous pollination can improve the yield. Different flowering varieties can improve the ability to resist the risk of inversion of spring frost and sand and dust hazards during flowering.
C、The planting of prunes
We generally take the garden planting plum. The planting density is 56 plants/667m or 28 plants/667m, and the row direction is north-south.
We usually plant prunes in spring. Usually planted in mid to late March. While lower tide saline soil is slow to warm up, can be planted in late March.
We generally adopt furrow planting and furrow irrigation. The ditch is 1m wide at the top, 0.8m wide at the bottom and 0.3m deep. The diameter of the hole is 0.8m, and the depth is 0.6m. Each hole can apply 10~30kg of well-rotted agricultural fertilizer, or mix with green manure, rice husk and licorice residue when burying the soil. We use the method of “three burial, two stepping and one lifting” to plant the seedlings. After planting, we need to water the plum in time, and cultivate the soil in the tree hole after 1 week, and correct the seedling.
D、Field management of plum
After planting, the plum tree can be covered with film or grass. This can play the role of moisture retention, alkali pressure. Plum young period, between the rows can be intercropped dwarf crops. After irrigation during the growing season, the soil needs to be loosened and weeded in time.
We apply basal fertilizer after the fruit harvest. Young plum trees are fertilized with 10kg/plant. 50kg/plant in fruiting season. The fertilizer is usually applied in a trench 40cm deep and 30cm wide, and we make a circular fertilizer trench along the peripheral projection of the crown of the plum tree. Then, we apply fertilizer evenly into the trench. Finally, we fill it in time. Or dig fertilizer ditch on both sides of the periphery of the crown, and rotate fertilizer application from east to west and from north to south in alternate years. At present, the most used water soluble fertilizer in the market comes from Nagric.
In a year, we need to chase fertilizer 2 times. Before flowering and fruit expansion, flower bud differentiation start period. Young plum trees apply 100~200g/plant each time. In fruiting season, 400g/plant is applied each time. The ratio of nitrogen, phosphorus and potassium is 2:1:2.
Fertilizer can be applied by trenching a shallow trench 15cm deep and 30cm wide in different directions under the canopy projection. After fertilization, we need to backfill the soil in time.
We generally irrigate before budding, during fruit development, at the beginning of flower bud differentiation, at the hard nucleation stage, after fruit harvesting and before soil freezing of prunes. The irrigation quota is 400~600m³/667㎡. The garden is built at the edge of the desert on the periphery of the agricultural area. If there are conditions, we advocate the use of water-saving irrigation methods such as drip irrigation or micro-sprinkler irrigation. According to the soil condition and evaporation, the irrigation cycle is 4~7 days. Each irrigation amount to infiltrate the soil 50 ~ 60cm of the main distribution layer of the root system is appropriate.
E、Flower and fruit management of prunes
We need to light piles of grass or smoke agent when the temperature drops below 3℃ in order to prevent the late frost from harming the flowering of prune. No less than 5 piles/667㎡, and evenly distributed in the prune garden. Spray 500 times of cyanophyll aqueous solution before flowering. This can delay the flowering period of prune and resist the low temperature hazard of late frost.
2、Fruit set rate
We generally use orchard bee release in order to improve the fruiting rate of prunes. This can improve the yield of prunes. We generally put one box of bees per 667㎡.
3、Shaping and pruning
The prune tree has strong branching power, weak stem and dense branches. We need to pay attention to open the inner chamber, ventilation and light. Retract or thin out the weak fruit branches, timely renewal and rejuvenation. Pruning consists of two periods: winter pruning and summer pruning. And mainly winter pruning, usually in early February. Summer pruning in May to July. While winter pruning, we mainly take to open the inner chamber, adjust the reasonable spacing of the prune branches.
At the same time, thin out the dorsal branches, dry branches, disease and insects and too dense branches. Shorten the strong branches, retract the weak perennial fruiting branches, and shake off the middle-aged branches. Top competitive branches to remove the strong and leave the weak, extension branches moderate short cut. In the summer pruning, we mainly use the angle of the main branch to support and open. The method of picking, twisting, taking branches, thinning out long branches and de-budding.