Gardening plants can be pruned at any time. However, some plants should be carried out during the period of least water secretion due to reasons such as water secretion. Most of our country is in temperate zone, and plastic pruning is mostly carried out in dormancy and growth period.

(A) dormant pruning (also known as winter pruning)

Pruning during this period is called dormant pruning or winter pruning (usually from 65438+February to February of the following year) before the sap begins to flow out in the early spring of the following year. During this period, due to the slow growth of trees, most of the nutrients in the trees returned to the roots, and the nutrient loss was the least after pruning, and the cut after pruning was not easy to be infected by germs, which had the least impact on the growth of trees. Therefore, most woody plants and a lot of pruning work are carried out during this time. The main purpose of dormancy pruning is to cultivate skeleton and tree shape. Some tree species that are prone to bleeding after pruning in the growing period, such as walnut, grape, maple, kiwi, cherry blossom and four-flowered flowers, should be pruned in winter.

(2) Pruning in growing season (also called summer pruning)

Pruning in this period is called growing season pruning or summer pruning (usually from April to September). During this period, because the trees in the growing season consume a lot of nutrients and store less nutrients, the leafy branches are cut off when pruning, which reduces the photosynthetic products and has a great inhibitory effect on the growth of trees, so the pruning intensity is generally light, so as not to hinder the overall growth of trees. The purpose of summer pruning is to control the occurrence and growth of competitive branches, bore branches, upright branches and long branches, so that nutrition can be concentrated on the vigorous growth of main branches. For trees with flower bud differentiation in summer and autumn, flower bud differentiation needs concentrated nutrition.

The determination of pruning period is not only restricted by regional conditions, biological characteristics of tree species and labor force, but also depends on nutritional basis, organ condition and pruning purpose. We should make a comprehensive analysis according to the specific situation and determine the reasonable pruning period and method in order to achieve the expected effect.

Second, the pruning method

Because the pruning period and position are different, the pruning methods adopted are also different. To sum up, whether it is pruning in dormant period or pruning in growing season, the methods adopted can be summarized as five words: "cutting, thinning, releasing, injuring and changing"

(A) the pruning method of dormant period

1.

(1) Cutting is also called short cutting (as shown in Figure 3-2), that is, cutting off part of annual branches. The function of short cutting is to stimulate the germination of lateral buds, increase the number of branches, increase the density of branches and leaves, which is beneficial to the accumulation of organic matter, thus promoting the differentiation of flower buds, regulating the balance of branch potential, and controlling the crown size and the length of branch tips; Conducive to vegetative growth and rejuvenation. The degree of short cutting affects the growth of branches, and the heavier the degree of short cutting, the greater the stimulation to the growth of single branches. According to the degree of short connection, it can be divided into light short section, medium short section, heavy short section and extremely heavy short section.

1) light chopping: cut off the branches of 1/5 ~ 1/4.

2) Medium and short cutting: cut off the branches of 1/3 ~ 1/2.

3) Re-cutting: 2/3 ~ 3/4 of the branches are cut off.

4) Extremely heavy and short cut: Most branches are cut off, leaving only 2-3 "shriveled buds" at the base.

In order to adjust the balance of tree potential correctly, we should pay attention to the quality and position of bud retention, especially the cut bud.

(2) Shrinking shear is also called retraction. Branch pruning shears are similar to short branch pruning shears, that is, cutting off the upper parts of branches to shorten the length of big branches, so they are also called branch pruning shears (as shown in Figure 3-2). It mainly occurs on branches over two years old. Shrinkage has dual functions, one is to reduce the total growth of the tree, the other is to provide nutrients and water for the branches behind the pruning parts, stimulate the germination of the buds behind them, and readjust the tree potential. In particular, contraction is conducive to rejuvenation and renewal, also known as renewal pruning.

Fig. 3-2 Short cutting, thinning and A- short cutting; B- thinning branches; Shrinkage shear

2. Sparse (also known as sparse or sparse)

Cut off the branch from the branch point (as shown in Figure 3-2). The application of bud wiping, leaf picking and tillering in the growing season also belongs to the category of thinning. Its function is to control vigorous growth and regulate the overall and local growth potential of plants; Improving ventilation and light transmission in crown and increasing assimilation are beneficial to the growth of branches in crown and the differentiation of flower buds. The main objects of thinning are weak branches, diseased branches, dead branches, cross branches, over-dense branches, sprouting branches, long branches and all other branches that disturb the tree shape. However, thinning does not stimulate nearby branches like short cutting, and will not cause a large number of branches. In addition, thinning can enhance the growth potential of branches below the incision, but weaken the growth potential of branches above the incision. Therefore, attention should be paid to avoid too many wounds and weaken the tree when thinning branches.

The thinning intensity is divided into light thinning (thinning 10% of all branches), moderate thinning (thinning 10% ~ 20% of all branches) and severe thinning (thinning more than 20% of all branches). The thinning intensity depends on tree species, age and growth. Tree species with weak sprouting and branching ability have fewer sparse branches. Chinese pine, Pinus massoniana, Populus davidiana, etc. If the branches are rotating, try not to be sparse. Tree species with strong germination and strong branches can be sparse, for example, Platanus acerifolia, steamed bread willow, Sophora japonica and so on. Young trees are lightly sparse, adult trees are moderately sparse, and old trees are only sparse to the branches that must be sparse.

Figure 3-3 Incision

be injured

The purpose is to destroy the bark, phloem and xylem of branches in various ways and weaken the growth potential of branches. Such as girdling, cracking, twisting, and grasping skills. In the dormant period, the carving method is usually combined with other pruning methods. Carved injuries are divided into eye injuries, longitudinal injuries and transverse injuries (as shown in Figure 3-3).

change

Methods the growth direction of branches was changed to alleviate the growth potential of branches. For example, bending branches, bending branches, coiling branches, pulling branches, supporting branches, spreading and other technical measures can change the angle and direction of branches and make the vertex advantage shift, strengthen or weaken. For example, the opening angle of the branches of Xifu Begonia is too small, so the growth direction of the branches can be changed by support to expand the crown. Some cup-shaped open-heart flowering shrubs can be shaped by pulling branches.

release

If you don't cut the nutrient branches, it is called throwing or growing. Release is a natural law that the growth potential of a single branch is decreasing year by year. For some branches with medium growth, the number of branches is relatively increased, which leads to the dispersion of nutrients in the early growth stage and the formation of medium and short branches; More nutrients are accumulated in the later growth stage, which can promote flower bud differentiation and fruiting. It is not appropriate to release branches that are growing too vigorously.

(2) Pruning method in growth period

1.

The measure of cutting off the top of the new tip is called coring (as shown in Figure 3-4). Kernel removal can concentrate nutrients on the lower leaves and branches, and promote flower bud differentiation and fruit setting; It is beneficial to improve the cold resistance of branches and the development of flower buds; Promote branching and increase crown width.

Wipe the bud

Erasing excess buds from the base is called wiping or removing buds. Its purpose is to improve the nutrient supply of the remaining buds and enhance their growth potential. For example, street trees erase hidden buds sprouting on the trunk every summer to ensure that the trunk is straight, reduce unnecessary nutrient consumption, and ensure that nutrients are supplied to the crown, making it broad and rich.

picking leaves

Cutting off leaves and petioles is called picking leaves. Removing leaves can improve the ventilation and light transmission conditions in the crown. For ornamental plants, it is beneficial to fruit coloring, increasing fruit aesthetic feeling and improving ornamental effect; Picking leaves can reduce and prevent the occurrence of pests and diseases; By picking leaves, you can also promote flowers.

4. Tillering (also called germination)

The sprouting branches that remove the base of the trunk or the big wound are called tillers. Grafted plants are easy to sprout rootstock buds at the roots, which is not conducive to the growth of grafted seedlings and should be pulled out in time.

5. Sparse flowers and fruits

Removing too many flowers and fruits is called thinning flowers (as shown in Figure 3-4) and thinning fruits. Too many buds or young fruits affect the flowering quality and fruit setting rate. For example, the residual flowers of Chinese rose flowers should be cut off after each flowering, so as to avoid consuming too much nutrition after fruit bearing and affecting the next flowering.

Fig. 3-4 flower thinning a before and after enucleation; B- after coring; C- flower sparse 6. Twist the tip (branch) and break the tip (branch)

Both are measures to sprain branches. Twisting refers to twisting the leafy branches from top to bottom (as shown in Figure 3-5), and breaking refers to not breaking new branches (as shown in Figure 3-5). Twisted tips and broken tips are harmless to the skin, but harmful to the bones. The purpose is to prevent the transport of nutrients, thus easing the growth potential. Promoting the formation of short branches is beneficial to the differentiation of flower buds. This method is often used to make bonsai.

Figure 3-5 twisted tip

7. Circumcision The measure of peeling off the cortex and phloem of a branch is called girdling, which is called girdling for short. Girdling can interrupt the downward transportation of organic matter and increase the accumulation of sugar above girdling, which is beneficial to the formation of flower buds and the improvement of fruit setting rate. The girdling should not be too deep or too shallow, and it is better to reach the xylem. The width is limited to one month after wound healing. Generally,110 has thick branches. This method is not suitable for bleeding plants.

Three, pruning procedures and matters needing attention

(1) The pruning procedure can be summarized as "knowing one thing, seeing two things, cutting three things, taking four things, handling five things and protecting six things".

One knowledge: the personnel involved in pruning work must understand the operating procedures and technical specifications; It is necessary to know the growth habits, new shoot development characteristics, flowering habits and some special requirements of the target plants to be pruned.

Second, look: don't prune trees when they grow. Before pruning, you should carefully observe the surrounding trees to understand the tree shape and the environment around the trees. Observe the growth of trees and branches, whether there are dead branches, pests and diseases, broken branches, big branches that don't need to be pulled out, etc. Pay attention to the pruning method, because the tree system should be pruned reasonably.

Three pruning: after understanding one thing and seeing two things, according to the principle of pruning according to local conditions and different trees, carry out reasonable pruning. Generally speaking, if big branches must be removed, they should be done first, and then small branches should be pruned. Trim from bottom to top, from inside to outside.

Four picks: the cut branches hanging on the tree after pruning should be taken down at any time and gathered together. Especially the branches hanging on the trees should be taken down in time to avoid danger to people under the trees.

Five treatments: the cut branches should be treated in a timely and centralized manner, and should not be delayed for too long, so as not to affect the city (garden) capacity and cause the spread of pests and diseases. It can be ground and fertilized or buried.

Six protection: namely, protect the cut after pruning. In order to prevent the wound from rotting due to bacterial invasion, tung oil, tung oil mixture, protective wax and cosmetic can be used to protect the wound.

(B) the technical points of pruning

(1) Location and shape of incision:

1) When chopping, it should be cut into horseshoe shape at the position of 0.5 ~ 1 cm above the leaf bud, and the right side of the bud has a high strategy, and the side far from the bud is slightly lower, about 30. If it is necessary to enlarge the crown, it should be cut short above the outward bud; If the branches need to grow inward, they should be cut short on the inward buds. The direction of bud retention should be determined according to the specific needs of the tree.

2) When thinning branches, you can cut off twigs at the base of the branch point. Thick branches (0.5 ~ 2 cm in diameter) should be cut off 2 ~ 3 mm above the skin ridge (the protruding part at the base of the branch) so that the wound can heal as soon as possible.

(2) Cutting off big branches: When cutting off big branches (more than 5cm), in order to prevent the branches from splitting, distribution operation can be adopted. First, you have to cut from the lower part of the branch about 20cm above the incision, and then cut from the top. Second, saw off the remaining stumps.

(3) When trimming, the incision should not be too large, and it should be smooth without leaving piles. So as not to affect the healing of the wound.

(III) Precautions for pruning

(1) During operation, keep concentration, and it is forbidden to have fun; You can't drink before climbing a tree.

(2) Each operation group shall appoint experienced old workers as safety and quality inspectors to be responsible for safety and quality supervision, inspection, technical guidance and publicity and education.

(3) Labor protection articles are necessary to ensure workers' operation safety. Work clothes and safety helmet must be worn in accordance with regulations, and labor protection equipment and articles such as safety belts and safety ropes must be fastened.

(4) When climbing a tall tree requires a ladder, you must choose a strong ladder and stand firm. One-sided ladder should be tied to the top rung and tree with rope, and the middle waist of herringbone ladder should be tied with rope and pay attention to the appropriate opening angle.

(5) Fasten your seat belt after climbing the tree, and the hand saw must be tied to your wrist with a rope.

(6) When there is a gale of magnitude 4 or above, it is forbidden to climb trees.

(7) When cutting off branches, experienced workers must direct safe operation.

(8) When pruning on street trees, special personnel must be appointed to maintain the site. Trees should cooperate with each other to avoid hurting passers-by and vehicles.

(9) Patients with hypertension and heart disease are not allowed to climb trees.

(10) The operating tools used for trimming must be firm and easy to use. The wooden handle should be smooth, so as not to affect the operation or even injure people by accident due to unqualified tools.

(1 1) After a tree is repaired, you are not allowed to climb to another tree, but you must come down from the tree before climbing.

(12) When working near high-voltage lines, pay special attention to safety to avoid electric shock, and ask the power supply department to cooperate if necessary.

(13) When several people are working on the same tree, there should be a special person to command and pay attention to coordination to avoid accidental injury to their companions.

(14) Before pruning the trees on the high car, all the parts on the high car must be checked to ensure that they are supported smoothly. During the operation, assign special personnel to check the situation of the high car at any time, and handle the problems in time when found.

(15) Be sure to fasten the safety rope after climbing the tree. Safety ropes should be tied to solid branches that will not affect the operation, and attention should be paid to putting them away at any time.