first, spring pruning
pomegranate trees are pruned in spring, from the bud stage after germination to the bud stage before flowering, usually from mid-April to May, mainly from late April to late May. At this time, the flower buds of the fruiting mother branch have sprouted fruiting branches and buds. The main pruning task in this period is to adjust the ratio between fruit branches and nutrient branches. But if we only adjust the proportion of branches, we still can't balance the relationship between fruit and vegetative growth. Because there are more than one flower on each fruit branch, it is often 1~5. If there are too many fruit sets (more than 2 per fruit branch), then in the fruit branch ratio of 1: 5 ~ 15, the number of leaves will be too small, and the fruit will not grow big, and the nutrition needed for the formation of new flower buds in that year will be insufficient, which will lead to the results of big and small years, that is, the output of that year is too much (big year) and the fruit is small, and the next year will be a small year with low output due to too few flower buds. Therefore, the tasks of pruning pomegranate trees in spring are as follows:
1. Adjust the proportion of fruit branches
Use pruning shears to remove too many tiny fruit branches or fruiting mother branches, so as to make the ratio of fruit branches reach a reasonable level.
2. Sparse buds and flowers
All bell-shaped buds should be wiped off with your fingers from budding to full bloom. For the flowers that have been opened, all bell-shaped flowers will be erased, leaving tubular flowers and gourd-shaped normal flowers. Bell-shaped flowers are degenerate flowers, which will never bear fruit and consume a lot of nutrients in the process of opening. The tubular flowers are intermediate normal flowers, and the fruit setting rate is not high. If the gourd-shaped flowers (normal flowers) are enough, the tubular flowers should be thinned together, leaving only the gourd-shaped flowers. Finally, it is appropriate to have 3~5 vegetative branches (with more than 1 leaves) around the fruit branches bearing gourd-shaped normal flowers. Such thinning of buds and flowers should be carried out 2~3 times during flowering. The production practice in many pomegranate producing areas has proved that thinning buds and flowers can obviously improve the fruit setting rate by 2~3% and increase the fruit yield, which must be seriously implemented.
3. Pruning pests and diseases
Pruning pomegranate in spring should also be done at the same time as thinning buds and flowers.
4. Bud smearing and sprouting removal
While thinning the buds and flowers, erase the densely sprouted shoots, the main branches, the tillers and sprouting branches above and below the main branches, so as to facilitate ventilation and light transmission and save nutrition.
second, summer pruning
summer pruning of pomegranate trees is carried out from June to July. The main pruning work is as follows:
1. Fruit thinning
In the first half of June (in the north), after the young fruits of 1~2 crops are seated, the small fruits in the double fruits are trimmed with fruit thinning, leaving only one big fruit. In addition, all diseased fruits, insect fruits and deformed fruits should be thinned out and buried deeply to prevent the spread of pests and diseases. According to the three crops of flowers and fruits, it is required to keep the first crop of fruits and choose the second crop of fruits. The third crop of fruits is often small and mature late, so it should be thinned out in general.
2. thinning branches
use pruning shears to remove dense, overgrown and diseased shoots and tillers. It is required that the light spots (sun shadows) under the canopy are evenly distributed on the ground after thinning. The spot area should be 1~15% of the total canopy projection area. The canopy after thinning is well ventilated and light-permeable, which can meet the requirements of "three thinning and three density", ensure high yield and high quality of fruits and good flower bud formation, thus achieving the goal of stable production.
3. Opening angle
If the main branches grow upright, and the spacing between the main branches can't reach the standard of 8~1 cm, the crown of the tree will be tight and the branches will be crowded. Therefore, it is necessary to spread the three main branches with wooden sticks or lead wires (fixed on the ground with wooden pegs). This is also an important measure to keep the canopy ventilated and transparent.
Third, pruning in autumn
From August to October, pomegranate trees often germinate many secondary and tertiary new shoots, which makes the crown branches dense, resulting in poor ventilation and light transmission, slow fruit growth and poor coloring, and also causes the formation of flower buds and the reduction of new fruiting mother branches by leaves and short branches. August-October is the peak period of rapid fruit growth, coloring and flower bud formation. Therefore, the tasks of autumn shears are as follows:
1. Thinning branches
As required in summer, the dense, overgrown branches and branches with diseases and insect pests will continue to be thinned, so that the crown is in a state of "three sparse and three dense", and the projected light spots of the crown are evenly distributed, so as to ensure that the fruits can directly see the light, and the leaves and short branches in the inner chamber can see enough light to form flower buds quickly. In addition, the fruits and branches of pests and diseases should be thinned and buried or burned to avoid future troubles.
2. Prune the root system after fruit picking and before defoliation
From mid-October to November, after fruit picking, all photosynthetic products made by leaves will be transported to differentiated flower buds and leaf buds, as well as branches and roots at all levels. First, promote the continuous differentiation of flower buds and ensure the yield of the next year; The second is to promote the growth of root system and send out a large number of new roots; Thirdly, a large number of photosynthetic products are stored in branches and roots to prepare for the differentiation and development of overwintering buds, and they are converted into soluble sugars to improve the winter cold resistance and drought resistance of pomegranate trees. Root pruning is combined with deep ploughing and fertilization in autumn. More new roots can occur on the roots cut off during deep ploughing and fertilization, which is beneficial to absorb more water and nutrients.
fourth, winter pruning
winter pruning is called dormancy pruning. After defoliation and before germination. In arid and cold areas, freezing injury is easy to occur in severe winter, and pruning can be carried out before germination in spring. The steps and key points of pruning in winter are as follows:
1. Treatment of big branches
The big branches should be treated according to the principle of "three sparse and three dense". The distance between the three main branches and the lateral branches should be 8~1 cm, so that their branchlets (branches) have a living space. When the distance between the main branches is small, the method of thinning or opening large branches can be adopted to make it meet the above-mentioned requirements for large branch spacing standards.
2. Treatment of branchlets
After the main lateral branches are spaced apart, the distribution of branchlets (large and small branches) on the crown is sparse on the top and dense on the outside. The density of the inner chamber branchlets is slightly denser than that of the upper and outer parts, but not too dense. The requirement is that the branchlets do not cross each other, do not overlap each other and leave some space. Leaving space means leaving space for the growth of new shoots after germination. For example, the length of the original twig is 3 cm, so it is necessary to leave 3 cm space for its development after thinning. That is to say, the branchlets not only do not cross and overlap each other, but also keep a space of 3 cm. Otherwise, the new shoots that occur in spring and summer after germination will seriously cross and overlap, forming a "three-density" tree without ventilation and light.
3. Treatment of fruiting mother branches
During and after thinning, it is necessary to identify flower buds and fruiting mother branches bearing flower buds. In order to keep as many fruiting branches with flower buds as possible, and keep 3~5 vegetative branches around them. If there are too many fruiting mother branches, some small fruiting mother branches can be thinned, leaving thick fruiting mother branches with large flower buds, and the ratio of fruiting mother branches to vegetative branches is roughly 1: 5 ~ 15, or the ratio is larger, 1: 5 ~ 8. If the original branches are too dense, no flower buds are formed or there are too few flower buds, then it is only necessary to trim them until the branchlets do not cross each other, do not overlap each other and leave room. For these branches, the ratio of fruit branches to vegetative branches can be adjusted when new flower buds appear after germination in the next spring. After winter pruning, the remaining fruit branches and vegetative buds can obtain relatively concentrated root nutrients, and promote the differentiation of flower buds and a small number of vegetative buds to transform into flower buds and fruiting mother branches.
4. Treatment of pests and diseases
When pruning pomegranate trees in winter, all pests and diseases should be thinned or cut off to reduce or eliminate the re-infected pests and diseases.