Also known as short cutting, it refers to the cutting treatment of annual branches. After the branches are cut short, the nutrients are relatively concentrated, which can stimulate the germination of lateral buds under the incision, increase the number of branches, and promote vegetative growth or flowering and fruiting. The degree of truncation has a significant effect on the pruning effect.

1, light and short cut off 1/5 ~ 1/4 of the total length of branches, which is mainly used for pruning strong branches of ornamental trees. After the branches are cut short, most of the semi-full buds are stimulated to germinate, forming a large number of short and medium branches, which are easy to differentiate into more flower buds.

2. Medium-short cutting is cut from the whole bud with the branch length of 1/3 ~ 1/2, which makes the nutrients more concentrated and promotes the emergence of stronger vegetative branches after cutting. It is mainly used for the cultivation of backbone branches and extension branches and the rejuvenation of some weak branches.

3. The heavy and short cut is in the middle and lower part of the branch, and the short cut is 2/3 ~ 3/4 of the total length, which has a great stimulating effect and can force the hidden buds at the base to germinate, and is suitable for rejuvenation and regeneration of weak trees, old trees and old and weak branches.

4. Only 2 ~ 3 buds are left at the base of extremely heavy and short spring shoots, and all the others are cut off. After pruning, 1 ~ 3 medium and short branches will germinate, which is mainly used for the treatment of competitive branches.

(2) Shrinkage and truncation

1. Retraction method, also known as shrinkage cutting method, refers to the pruning method of shortening perennial branches (branches). When the growth potential of trees is weakened, some branches begin to droop, and baldness appears in the middle and lower part of the crown, this method is often used to rejuvenate the aging branches and renew the fruiting branches, so as to promote the vigorous growth of branches below the incision or stimulate dormant buds to germinate and grow branches, thus achieving the purpose of rejuvenation. (fig. 10-3).

2. Trunk is a measure to retract trunk, thick main branch and backbone branch, which can effectively adjust the contradiction between water absorption and transpiration balance of trees and improve the survival rate of transplanting, especially when transplanting big trees. In addition, the crown structure of strong trees can be transformed by the function of forced hidden buds, so that old trees can be rejuvenated.

(3) Sparse

Also known as drainage or drainage, that is, the pruning method of cutting branches from the base of branches. Thinning can reduce the number of branches in the crown, make the distribution of branches tend to be reasonable and uniform, improve the ventilation and light transmission in the crown cavity, enhance the assimilation function of trees, reduce the occurrence of pests and diseases, and promote the vegetative growth or flowering and fruiting of branches in the crown cavity. The main objects of thinning are weak branches, pests and diseases, dead branches, cross branches, interference branches and budding branches that affect tree modeling. In particular, the upright branches sprouting on the crown have small buds, long internodes, thick, rich water and insufficient tissue, so they should be drained as soon as possible to avoid affecting the tree shape; However, if there is room for growth, it can be transformed into branches, which can be used for the renewal and transformation of crown structure and the rejuvenation of ancient trees.

Thinning can weaken the overall growth of the whole tree, but promote the local growth of the tree. The local stimulation of thinning is different from short cutting. It strengthens the branch below the ipsilateral incision, but weakens the branch above the ipsilateral incision. It should be noted that thinning branches will form wounds on the mother branches, thus affecting the transport of nutrients. The thinner the branches, the closer the wound spacing, and the more obvious the weakening effect. The weakening degree of the whole tree growth is related to the thinning intensity and the strength of the thinning branches. If the thinning intensity is high and the branches are weak, the growth of trees will be greatly weakened. Thinning perennial branches has a great weakening effect on the growth of trees, and it is generally appropriate to carry out it in stages.

Thinning intensity refers to the proportion of thinning branches in the whole tree. Thinning 10% of the branches is light thinning, and more than 20% of the branches are cut when the strength reaches 10 ~ 20%. In practical application, the thinning intensity depends on the specific conditions such as tree species, growth and age. In general, tree species with strong germination rate, weak branching ability or weak budding and branching ability should be sparse, such as Pinus massoniana, Pinus tabulaeformis and Cedar. Trees with strong germination rate and strong branch formation can be thinned more; Young trees should be light and sparse to promote the rapid expansion of crown; Adult trees entering the peak period of growth and flowering should be properly thinned to adjust the balance between vegetative growth and reproductive growth and prevent flowering and fruiting. The branching ability of aging trees is weak, so in order to keep enough branches to form a crown, it should be as sparse as possible; Flower shrubs, light thinning can promote the formation of flower buds, which is conducive to early flowering.

(4) Injury

The method of damaging the phloem or xylem of branches to weaken the growth potential of branches and relieve the tree potential is called injury. Most of the damaged branches are carried out in the growing season, which has a great impact on the local area and has little impact on the growth of the whole tree. It is one of the auxiliary measures of plastic trimming, and the main methods are as follows:

1. girdling (girdling) Use a knife to girdle bark with a certain width at the proper part of the branch or at the base of the branch, so as to prevent photosynthetic nutrients from being transported downwards at the tip of the branch for a period of time, which is beneficial to the accumulation of nutrients above girdling and flower bud differentiation, and is suitable for branches with vigorous vegetative growth but few flowering and fruiting. The peeling width depends on the thickness of branches and the healing ability of tree species. Generally, the wound can heal within 65,438+0 months, which is about 65,438+0/65,438+00 (2 ~ 65,438+00 mm) of the branch diameter. If it is too wide, the wound will not heal easily; if it is too narrow, it will heal prematurely. The depth of girdling should reach xylem. Too deep xylem damage will cause the girdled branches to break or die. Too shallow will leave phloem, and the girdling effect is not obvious. There should be enough branches and leaves above the girdling branches to facilitate normal photosynthesis.

Circumcision is a temporary pruning measure applied in the growing season, which is usually carried out in the flower bud differentiation period, flower and fruit falling period and fruit expansion period. When pruning in winter, the above part of girdling should be gradually cut off. Trunk and main branches can also be circumcised, but it must be carefully decided according to the growth of the tree. Generally used for young and strong trees with strong trees and few flowers and fruits. Trees with excessive bleeding and easy gum flow should not be girdled.

2. The method of cutting the upper (or lower) side of the branch bud with a cutting knife and deeply cutting into the xylem is often used in combination with other pruning methods. The main methods are:

1) The eye wound is carved above the branch bud, and the shape of the wound is like an eye, which damages the xylem and prevents water and mineral nutrients from continuing to be transported upwards, thus sprouting strong branches in the ideal position; On the other hand, cutting off the lower branches and buds can weaken the growth potential of branches, but the accumulation of organic nutrients is beneficial to the formation of flower buds.

2) Longitudinal injury refers to cutting branches with a knife that goes deep into xylem to reduce the mechanical binding force of bark and promote the thickening and growth of branches. The longitudinal injury should be carried out before the trees begin to grow in spring, and the hardened part of the bark should be selected when implementing. For branchlets, one longitudinal injury is feasible, and for thick branches, several longitudinal injuries are feasible.

3) Transverse injury refers to the method of cutting off the trunk or thick main branches with several knives, which is used to block the downward backflow of organic nutrients, promote the enrichment of branches, promote the differentiation of flower buds, and promote flowering and fruiting. The mechanism of action is the same as that of girdling, but the strength is lower.

3. Broken branches make them form various artistic shapes, often in the early stage of germination in early spring. First, cut it obliquely with a knife to the depth of 1/2 ~ 2/3 of the branch diameter, then carefully bend the branch, and support it with an inclined plane at the cracked xylem (Figure 10-4). In order to prevent the wound from losing too much water, the wound is often bandaged.

4. Twisted branches and broken branches (branches) are mostly used for semi-lignified branches that grow excessively in the growth period, especially long branches that grow on the back of branches. Twisting without breaking is called twisting bamboo shoots (figure 10-5), and breaking without breaking is called breaking bamboo shoots (figure 10-6). Twisted branches and broken branches damage the conducting tissue, hinder the transport of water and nutrients to the growing point, weaken the growth of branches, and are beneficial to the formation of short flower branches.