1. Pruning of young trees: Young pear trees include non-bearing trees and early-bearing trees, and most of them are under 10. Its pruning tasks are, first, to cultivate backbone branches at all levels through crown shaping, and second, to leave enough auxiliary branches and cultivate fruiting branches. Its pruning characteristics are: First, strictly control the top advantage, prevent the top from being strong and the bottom from being weak, and pay attention to opening the backbone branches in time. Second, when cultivating branches, we should pay attention to less thinning and more retention, cut first and then release, and cooperate with summer pruning to achieve the purpose of increasing branches and promoting flowers. Generally, it is short and long branches, and the medium and short branches are slowly put. In the early stage of young trees, the root system is weak, the branches are few, and the crown grows slowly. It is necessary to leave as many branches and leaves as possible to raise roots. The vigorous branches should be controlled and reformed by taking branches, bending, carving, coring and other techniques to make them blossom and bear fruit as soon as possible. The extension heads of main branches should be cut off properly, and large and medium-sized branches should be cultivated in the middle and lower parts with the cut branches to prevent the growth and fruiting parts from moving out due to the lack of bare branches in the lower parts of main branches in the middle and late stages of big trees.
2. Pruning of fruiting trees: fruiting trees mainly refer to big trees in full fruit period, mostly after 10 ~ 13. Pruning tasks are mainly to balance the tree potential, control the crown size, cultivate "three-match" robust branches, retract and update long and weak cross-bearing branches and "chicken feet" weak and short bearing branches, and sparse flowers and fruits for reasonable load to prevent year after year. In addition, the crowded branches in the periphery should be removed in time to improve the illumination in the crown, reduce the outward migration of the fruit and improve the quality of the fruit. The overall pruning characteristics of crown should be "thinning inside and outside, strengthening tree potential and good results"
3. Pruning of aged trees: An aged tree refers to an aged tree that is over 50 to 60 years old and its branches are obviously weak. The characteristic of this tree is that the peripheral branches grow very little, and new branches are produced in the inner chamber and lower part, which grow centripetally. Judging from the results, the parts often move out seriously because of their small size and poor quality. The pruning task is mainly to retract and renew the weak and aging branches and leaves, and combine with thinning flowers and fruits to restore the vitality of the tree as soon as possible. Retraction should be carried out from local to whole, from branch group to branch group in a comprehensive and planned way, and it is not allowed to retract too much and too fast at once, which will weaken the tree potential due to excessive injury. The recovery of branch groups can be carried out in stages and in batches. When cutting branches, we should pay attention to the method of "keeping small first and retiring from old age", that is, before cutting branches, we should improve the nutritional conditions of cutting branches by reducing the number of fruits, so that their growth potential will become stronger. At the cutting parts, we should first inhibit the former, then promote it by fencing and girdling, so that the lower latent buds germinate and produce new branches, and select the branches with strong back as new branches for cultivation. If there are new branches sprouting from the lower back, you can also shrink directly here. After the branches are retracted, the wounds should be disinfected and protected to ensure the normal growth of new branches. At the same time, we should also pay attention to the transformation and utilization of long branches sprouting at any time in various parts of the crown.
In short, young trees grow vigorously, so we should pay attention to opening branches and branching, and we can change our heads with the branches at the back when pruning. When the old tree is weak, attention should be paid to the elevation of the growth angle of the branches, and the branches on the back should be replaced when retracted. This is the pruning experience summarized by fruit farmers in pear areas, that is, "the cutting edge of young trees is above and the cutting edge of old trees is below" (Figure 2 1).