Pruning of cherries can be divided into summer pruning and winter pruning.
Summer pruning: the purpose of summer pruning is to reduce the ineffective growth of new shoots, increase the amount of branches and leaves, improve the lighting conditions, and make the tree shape early, blossom early and bear fruit early. The main pruning methods are: opening angle, removing core, twisting tip, wiping bud, girdling, girdling and so on.
Winter pruning: Winter pruning refers to pruning after the trees enter the winter dormancy period. The main methods are: short cutting, slow release, retraction, refinement and so on.
2, the main tree and plastic process
Natural happiness: This tree is similar to the natural happiness of peach trees. Trunk height is 30-40 cm, and there is no trunk. The whole tree has 3-5 main branches with an opening angle of 30-40 degrees. Each main branch has 2-3 lateral branches, which extend outward at an opening angle of 70-80 degrees. Different types of fruiting branches are cultivated on the main branches and lateral branches. The height of the tree is controlled at about 3 meters, and the crown is flat or round.
Improved trunk shape: the trunk is 50-60 cm high and upright. The trunk is equipped with more than 65,438+00 main branches extending in a single axis, and the spiral is concentrated in the central trunk with a nearly horizontal angle; The main branch can be layered or not, and the bearing branch group is planted on the main branch; The height of a tree is generally about 3 meters. Planting density can be higher when it is low, and shorter when it is high.
Free spindle shape: there are 1 upright and stout central trunk, and the whole tree has 10- 12 small main branches distributed in the middle trunk. The lower main branch is longer and the upper main branch is shorter, and the ratio of dry branch to branch is 3-3.5: 1. The main branches can be arranged in layers of 3-4 bases, and the distance between layers is 30-40 cm, and then the main branches are inserted upward evenly in a spiral shape without layering. The main branches are big and small. The opening angle of the main branch on the same tree varies according to the position z of the main branch. The lower branch is 80-85 degrees, and the upper branch is 85-90 degrees. The whole tree has main branches, no side branches, and the bearing branches are directly on the main branches.
Slender spindle shape: it has a central trunk, with a trunk height of 40-60 cm, a tree height of 2-3.5 m and a crown width of1.5-2.5 m. The first layer has three main branches, and there are no side branches on the main branches, which directly bear fruit branches. 15-25 horizontally growing lateral branches with the same size are evenly distributed on the central trunk above the main branch of the first layer, which are distributed in rotation, regardless of levels. The lower branches are slightly longer, the upper branches are slightly shorter, the whole tree is slender, the top is sharp, and the whole tree is slender and spindle-shaped, which is suitable for close planting in dwarfing culture.
Small crown sparse type: the stem height is 30-60 cm, the tree height is 3.0-3.5 m, the crown width is 3.0-3.5 m, and there are 6 main branches, which are divided into 3 layers, 3 1 layer, 2/layer and 3 1 layer. The base angle of the main branch is 60-70 degrees, and the spacing between layers is 60 cm. The main branches above the second floor do not leave side branches, and the bearing branches are directly planted.
Hedge wall modeling: its vertical frame is similar to the double-arm vertical frame of grapes in the form of a tree, and the branches of sweet cherries are tied on the wire frame to form a hedge wall modeling.
3. Problems needing attention in cherry pruning.
The main problems are as follows: ① There are too many short sections, too long short sections and too many big branches in young tree modeling, which leads to crowded branches, poor lighting conditions and disordered tree shape; (2) All fruit trees will become shorter when pruning, regardless of variety; (3) Prune trees regardless of their strength; ④ The same pruning method should be adopted regardless of the growing season and age.
Problems that should be paid attention to: ① Pruning in winter can be carried out during the whole dormant period, but the later the cherry is, the better, and pruning in bud is generally appropriate. ② The flower buds of cherry are lateral pure flower buds, and the terminal buds are leaf buds. After flowering and fruiting, the flower buds form blind nodes and no longer germinate. When pruning the fruiting branches, the cutting buds should not stay on the flower buds, but on 2-3 leaf buds above the flower bud segments. (3) After the branches of trees are injured, they are easily infected by germs, leading to glue leakage or disease. Therefore, in field management, special attention should be paid not to damage trees and branches. Cherry trees should be carefully girdled, and it is easy to flow off after girdling. ④ Cherry likes light and has strong polarity. When pruning, if there are too many short peripheral branches, there will be too many peripheral branches, and the branches will be crowded tightly, and the upper branches will be stronger than the lower branches. ⑤ Pay attention to variety characteristics. The wound healing of big cherry trees is slow after girdling, so the girdling width should not exceed 0.5cm, and because of the different vigor of big cherry trees, especially the application of organic fertilizer ...
Question 2: When and how to prune cherry trees? Pruning cherry trees in winter can be done from 10 day after defoliation in autumn to about half a month before germination in spring, and it is best to finish pruning in 65438+ 10 month in solar calendar.
The key points of cherry tree pruning in winter are: according to the basic tree shape, choose the appropriate tree shape (natural joy shape, small crown shape, sparse layer shape); Pruning is mainly to remove (cut off from the base) erect branches, over-dense branches, over-thin branches, cross branches, overlapping branches, pest branches and so on. Back to improve the illumination of the crown hall; Give priority to thinning and take as few shortcuts as possible.
In the young tree period, we should pay attention to the angle of opening the main branches, relax the tree potential and bear fruit early.
Question 3: How to prune cherry trees? Pruning cherry trees in winter should not be too early, but should be postponed until it is close to germination. In order to control the flourishing length of branches, increase the amount of branches and leaves, accelerate the expansion of crown and promote early fruiting, pruning of young trees in summer can be carried out after fruit picking, mainly by thinning branches, that is, thinning branches that are too dense and too flourishing to adjust tree structure and promote flower bud differentiation.
Question 4: What is the correct pruning method for cherry trees? Pruning of cherries can be divided into summer pruning and winter pruning.
Summer pruning: the purpose of summer pruning is to reduce the ineffective growth of new shoots, increase the amount of branches and leaves, improve the lighting conditions, and make the tree shape early, blossom early and bear fruit early. The main pruning methods are: opening angle, removing core, twisting tip, wiping bud, girdling, girdling and so on.
Winter pruning: Winter pruning refers to pruning after the trees enter the winter dormancy period. The main methods are: short cutting, slow release, retraction, refinement and so on.
Question 5: How to prune cherry trees? First of all, according to different planting methods, choose the appropriate tree shape.
If the plant spacing is about 2x4m, spindle pruning is adopted; If the plant spacing is 3x4m, small crown and sparse layer pruning should be adopted; If the plant spacing is 4x4m, open-heart pruning shall be adopted; If the plant spacing is 1.5x3.5, unilateral tree pruning will be adopted.
The cherry trees planted in the courtyard mainly adopt natural and happy pruning.
Plastic pruning is mainly carried out in winter dormancy period (it is best to finish pruning before germination 1 month).
The key points of pruning cherry trees in winter are: thinning straight branches, over-dense branches, weak branches, overlapping branches, cross branches, pest branches and so on. Back, and improve the lighting of the hall inside the crown. For young trees that have not yet borne fruit, it is necessary to widen the angle of main branches to ease the tree potential; Trees with too many flowers should properly remove some buds to prevent them from bearing fruit in different years.
Question 6: What about the pruned part of the cherry tree? How to prune cherry trees?
2 methods: Pruning small cherry trees Pruning mature trees is necessary to create good growth conditions for cherry trees and make them bear beautiful fruits every year. Small cherry trees should be trimmed into vases to allow light and air to circulate and spread between branches. In the next few years, dead branches and infected parts should be cleaned up in time to ensure the health and strength of trees. Please refer to step 1 to learn how to prune your cherry tree at various stages.
Method-1
1 disinfect your pruning shears and sharpen them. Washing and cutting branches and leaves with dirty and blunt pruning shears will make them infected with diseases. Make sure your scissors are sharp, so that you won't damage the branches when pruning. Disinfect the pruning shears carefully before pruning your tree every time. It may take a few minutes, but it's worth it to make sure you don't hurt the cherry tree when pruning. Sterilize your pruning shears.
Mix the bleaching agent of 1 to 9 with the aqueous solution.
Dip your scissors in the solution.
Rinse with hot water.
Dry with a clean towel.
Move 60-90 cm from the top of the tree. Determining the height of the middle trunk is to cut it off from the top of the middle trunk to promote the growth of the lateral branches. It is important to do this in the first year or two after planting a tree, so that you can control its growth shape. Before fixing the valve stem, measure whether it is high enough. If the saplings are short, wait until they are at least 75 cm taller than when they were planted. When the tree is planted better, it will not cause too much damage to the tree.
It is dry in autumn or winter, during which the trees are still dormant. If you wait until spring, the trees will sprout. When you prune trees after the buds grow, the energy entering the buds is wasted. Fixing the trunk before germination allows the tree to use this energy to grow healthy branches.
Pruning at a 45-degree angle makes trees less likely to get sick and rot.
A year later, make a spiral scaffold. Spiral scaffolding consists of lateral branches extending from trees. They provide architecture and keep the shape of the tree balanced. The next winter, when you decide to dry it, when it sleeps again, choose four strong and evenly spaced branches as the first spiral scaffold.
Look for big branches that are at an angle of 45 or 60 degrees to the trunk. These are the best branches. [2]
Choose four branches, the vertical spacing is about 20 cm, and the shortest branch is about 45 cm above the ground.
Cut all four branches into 60 cm. Cut off tree buds at an angle of 0.6 cm; New buds will grow where you cut.
Cut off the remaining branches. Make the cut pieces flush with the trunk, so that only these branches belong to the spiral frame.
There should be two secondary branches under each main branch. Find two sturdy secondary branches with appropriate spacing to support them. Cut the remaining branches so that they are flush with the basic branches. This can help the tree concentrate on those branches that can bear better fruit.
Question 7: How to prune the big cherry tree? Our company has all kinds of big cherry trees. One is to apply base fertilizer in autumn. Because the big cherry germinates and blooms with the nutrients stored in the tree, the base fertilizer plays a decisive role in the growth and development of the tree in the coming year. If base fertilizer is applied early, the fertilizer efficiency can be exerted in that year, and the nutrient reserve before overwintering can be increased, which is beneficial to the decomposition of organic fertilizer and the release of nutrient elements. Because September is at the peak of the root growth of big cherry, it is beneficial to the absorption of nutrients, and at the same time, the damaged root system can be well restored, which is beneficial to the regeneration of multiple roots. At this time, farmyard manure, phosphate fertilizer and appropriate nitrogen fertilizer are mainly applied. Farmhouse manure should be fully decomposed before application to avoid burning the roots. Young trees should be furrowed and deeply applied at the crown projection, and trees should be combined with ploughing and throwing seedlings in the whole garden during the full fruit period. The amount of base fertilizer accounts for about 70% of the annual fertilization. Generally, 30 ~ 50 kg of human manure or 5 ~ 8 kg of pure chicken manure are applied to young trees during crown expansion. In order to promote the early formation of crown, nitrogen fertilizer 150 g can be applied to each plant. Generally, 60 ~ 80 kg of human manure or 20 ~ 30 kg of pure chicken manure are applied to each tree in the full fruit period; At the initial fruit stage, trees can add appropriate amount of compound fertilizer to control nitrogen, increase phosphorus and supplement potassium.
Second, weed control. There are four ways to weed in cherry orchard: one is manual weeding; The second is to press grass with plastic film; The third is orchard mulching, which covers the soil with uncultivated organic matter such as cut weeds and crop straws to suppress weeds; Fourth, use chemical herbicides. Commonly used herbicides are: withered grass, gramoxone, atrazine, ethyl acetate mixture, glyphosate, simazine, diuron and so on.
Third, foliar spraying fertilizer. Generally, it should be done in the morning and evening on cloudy or sunny days. The leaves should be well absorbed to prevent phytotoxicity, and sprayed on the back of the leaves for easy absorption. Commonly used foliar fertilizers are 0.05% ~ 0. 1% zinc sulfate solution, 0.2% ~ 0.3% borax, 300 times amino acid compound micro-fertilizer, 0.5% ~ 0.8% urea, 0.2 ~ 0.5% potassium dihydrogen phosphate, etc. From mid-August to mid-September in autumn, spray once every 10 ~ 20 days, and spray 2 ~ 3 times.
Fourth, pick the heart and pull out the branches. At the end of July and the beginning of August, a small number of new shoots appeared in the inner cavity of the tree, which can be left for about 20 cm to pick the core in time, control the vigorous growth, promote maturity and form fruiting branches. The effect of opening branches of big cherry in autumn is better than that in spring. The base angle of the first main branch of big cherry is about 80 degrees, and the sharp angle is 65 ~ 70 degrees. The branch opening angle of auxiliary planting is 80 ~ 90 degrees. When pulling branches to open corners, pay attention to moving ropes or falling objects in time to prevent sharp corners from growing centripetally.
Fifth, thin out the big branches. In the middle and late August, the upright branches, over-dense branches and over-flourishing branches on the back are removed in time, so as to improve the illumination in the inner chamber and enrich the flower buds. The inner chamber of the tree is empty, and the robust branches in the inner chamber 1 ~ 2 years can be appropriately shortened, which promotes the growth of branches, cultured branches or fruiting branches. Leave 1 ~ 2 branches to go out on the peripheral branches of Dazi, Hong Guang and Binku, and the other branches should be thinned in mid-September, which is easy to cause glue flow during dormancy, and cannot be thinned.
Sixth, soil improvement. Soil improvement cannot cut corners. We should turn the topsoil as deep as possible to make the living soil thicker. When digging the soil deeply, we should use some fertilizers with high organic content, or bury some fermented crop stalks in the ground to improve the organic content of the soil in cherry orchard, which can make the trees of big cherry develop well. Even if there is less fertilizer in the later management process, it will not affect the bumper harvest of big cherry.
Seven, pest control. Although the active prevention and control in the early stage effectively controlled pests and diseases, it does not mean that they were completely eliminated. There are many rainy days in September, and germs are easy to spread. At this time, we should pay attention to the rotation of drugs in pest control. In autumn, 2.5% triadimefon can be sprayed 3000 times on bridge-building insects, awning caterpillars and peach leaf miner. Spraying 200 times of Bordeaux mixture or 0.3-0.5 degree stone sulfur mixture in mid-July and mid-August respectively can control leaf perforation.
Eight, plastic trimming. Experience has proved that string shape is most suitable for big cherry. Tree-shaped stems are low, fast forming, early fruiting, lodging resistance, good lighting conditions, high quality and high yield. The shaping method is to set the height of the stem at 20-30 cm, evenly grow 3-5 main branches from the base, leave 40-50 cm long for coring in summer, or 40-50 cm for pruning in spring, and then divide them into relatively balanced lateral branches or fruiting branches, and plant small fruiting branches or fruiting branches on them.
Nine, pour frozen water. 165438+1Before the soil freezes in June, the whole garden should be watered with frozen water to keep moisture, prevent peeling and protect trees from overwintering safely.
Ten, the trunk painted white. Whitening the trunk can avoid or reduce freezing injury.
Question 8: How to prune small cherry trees and peach trees?
Winter pruning: short pruning, thin pruning, long paving and retraction.
(1) Short cut: Cutting off part of annual branches is called short cut. There must be leaf buds when the short branches are cut. The function of short cutting is to reduce the number of leaf buds and flower buds on short cutting branches, strengthen the growth ability of new shoots of short cutting branches, reduce the branch position and enhance the branch ability.
Light and short cutting: cut off the total length of annual branches within 1M5. The new shoots sprouted in the following year have weak growth potential, but there are many new shoots, which are mostly used to cultivate medium, short and bouquetlike fruit branches. Or increase the number of fruiting branches and control the growth of new shoots after lightly cutting strong fruiting branches.
Short and medium cuttings: Cut off 1M2 of the total length of annual branches, and all the buds under the cuttings are full. The new shoots germinated in the second year have strong growth potential, and a large number of robust new shoots are extracted, which are mostly used to prune the extension branches of the main side branches.
Heavy and short cutting: 2M3~3M4 of the total length of annual branches are cut off, and the plumpness of buds under the cutting mouth is poor, but the pruning amount is large, so the new shoots sprouting in the next year have strong growth potential, but the number of new shoots is small, which is mostly used to control the pruning of strong branches.
Extremely heavy short cutting: the total length of one-year-old branches is more than 5M6, and the sprouting branches in the second year are weak. This cutting method is mostly used to cultivate fruit branches with developing branches and overgrown fruit branches.
(2) thinning the branches from the base, which is called thinning, also called pruning. Thinning branches can reduce the density of branches in the crown, improve the ventilation condition of the crown, make the storage nutrition in the tree relatively concentrated and promote the growth of new shoots; Pruning will inhibit the upper part of the wound and promote the lower part of the wound. Removing useless twigs, diseased branches, clustered branches, overlapping branches and shady branches can promote the growth of the remaining branches.
(3) Let the annual branches grow naturally without pruning. Long-term planting can keep the most buds on branches and slow down the growth of new shoots in the next year. Too long fruiting branches or long fruiting branches with excessive growth potential will weaken the apical dominance and promote the formation of short and medium fruiting branches.
(4) Internal contraction refers to the short cutting of perennial branches, also known as reduction. Retraction can reduce the total length of branches, concentrate nutrients and water on the remaining branches, promote the growth of lower branches, and be beneficial to the rejuvenation of trees. Its function is to improve the light conditions in the crown, reduce the fruiting position, change the extension direction and angle of the extension branches, control the crown and prolong the fruiting period.
Problems needing attention in pruning peach trees
1. After pruning, the cut of the branch should be smooth, with a 45-degree slope with the cut bud, cut from the reverse side of the bud, the upper part of the slope is flush with the cut bud tip, and the lowest part of the slope is flush with the bud base, so that the cut wound is small, easy to heal, and the bud grows fast after germination. Cut off the opening of thinning branches, cut off at the branch point, and leave no stump even on the stem.
2. When pruning larger branches and trunks, the split operation method can be adopted. First, cut the kerf upward from the lower part of the branch at a position 20 cm above the required kerf, the depth is half of the thickness of the branch, and cut the branch from the upper part, leaving a residual pile, and then saw off the residual pile from the kerf to avoid splitting the branch.
3. In order to prevent the branches from rotting due to rain or bacteria invasion, the kerf must be smooth, disinfected with 20% copper sulfate solution, and finally coated with protective agent (protective wax, ready mixed paint, etc.). ) prevent corrosion and drying, and promote healing.
(Source quoted from "Questions and Answers on Key Technologies of Peach Production", China Agricultural Publishing House; Peasant workers 2009+0438+0
Summer pruning technique
(1) In the foliage stage (3~5 cm), the competitive buds of strong branches and extended branches from the upper part of the back of main branches and lateral branches, on the trunk and near the big incision were all erased. Remove double buds, leaving single buds, dry branches, branches of diseases and insect pests, waste buds, and reduce long fruitless branches. The sprout of rootstock should be cut off as soon as possible. By removing sprouting and smearing buds, useless new shoots can be reduced, nutrition can be concentrated, and the remaining branches can be fully developed, and flower buds and leaf buds are full. Sprouting can improve the light condition of the crown, greatly reduce the workload of pruning in summer and the damage caused by pruning branches in summer.
(2) Peeling is easy to produce branches, and peach trees themselves have a large number of secondary branches, which are more likely to cause too many secondary branches and close the crown. At present, except for young tree pruning, the main lateral branches need to be cored, and peach tree pruning in summer generally does not advocate new shoots.
(3) When new shoots are semi-lignified, there is room for twisting and competing branches near the extension branches of main branches and lateral branches, for example, strong long branches and upright branches become lateral branches or large and medium-sized fruiting branches, and the long branches with few fruits or the parts of main branches that are easy to get sunburned. ......& gt& gt
Question 9: Should cherry trees be pruned frequently? When do you usually trim it? How to trim? What nutrients are generally needed to increase the fruit yield in the coming year? Soil, fertilizer and water management
According to our experimental observation, the soil management of cherry should be covered by irrigation in spring and weeding in other seasons. Because mulching reduces the influence of spring drought on plants, it has a good effect on fruit growth. After harvesting cherries, remove or turn over the mulch. According to estimates, the average adult garden should cover 2000 ~ 2500 kilograms of straw per mu. Cherry trees should be fertilized 3-4 times a year. Namely:
Fertilization after fruit picking
Mainly to restore tree vigor, promote flower bud differentiation and increase annual output in the coming year. Manure, livestock manure and urine should be applied immediately after fruit picking, and appropriate amount of chemical fertilizer should be added. According to the results, 30 ~ 60 kg of livestock manure should be applied to each crop.
Fertilization before germination and flowering
Topdressing available nitrogen fertilizer. Apply/kloc-0.5 ~ 20kg of livestock manure or 0.5kg of urea per plant.
Rapid long-term fertilization of fruits
After the flowers wither, they enter the fruit development. Quick-acting chemical fertilizer should be applied to fruit trees at one time, and appropriate amount of phosphorus and potassium fertilizer should be applied.
Apply base fertilizer well
From September to 65438+1October (southern warm area10 ~165438+1October), basal fertilizer was applied before defoliation to rejuvenate the trees and increase the nutrient content stored in the plants. Because it only takes more than 40 days from flowering to fruit ripening, the amount of stored nutrients greatly affects the size and quality of fruit. Therefore, the application of base fertilizer is very important, accounting for 50 ~ 70% of the annual fertilization. Organic fertilizer should be the main fertilizer, such as compost, manure, rotten bean cake, etc. And adding calcium superphosphate or calcium phosphate fertilizer appropriately.
In addition to the above-mentioned soil fertilization, spraying 0.5% urea, 600 times of potassium dihydrogen phosphate solution or 0.3% borax solution/kloc-0 every day from early flowering to full flowering is helpful to improve the fruit setting rate.
Do plastic surgery
Natural tuft
This is a common tree shape of China cherry. Generally, there are 5-6 main branches, which spread around and grow, and each main branch has 3-4 side branches. The fruiting branches are attached to the main branches and side branches. After the main branches are aged, they are regenerated by sprouting. This tree has a wide angle, fast forming and early fruiting. However, the inside of the crown is easy to close.
Natural happy shape
Mainly used for sweet cherries. The stem is 30 ~ 40 cm high, and the whole tree has three main branches with a branching angle of 30 degrees. Initially, the central stem was retained, and after 4-5 years of planting, the central stem was removed to form a happy shape. This tree has the advantages of easy shaping, small pruning, open crown, good ventilation and light transmission, early fruiting, high yield and good fruit quality.
Trunk thinning
The stem is 40 ~ 60 cm high and has a central stem. The number of main branches is 6-7, which are scattered on the central trunk in 3-4 layers. There are three main branches on the first floor, with an opening angle of 50 ~ 60 degrees; There are two main branches on the second floor, the opening angle is about 45 degrees, and each of the third and fourth floors has 1 main branch. The spacing between the first and second floors is 60 ~ 80 cm, the spacing between the second and third floors is 40 ~ 50 cm, and the spacing between the upper floors can be appropriately smaller. There are 2 ~ 4 lateral branches on each main branch. At the same time, the fruiting branches are cultivated on the backbone branches at all levels.
Y-tree
This tree runs north and south, and each plant has two symmetrical main branches. During plastic surgery, it is necessary to set up a support frame for binding. This kind of tree has good ventilation and light transmission, easy flowering and fruiting, suitable for close planting, convenient management and good fruit quality.
decrease
Matters needing attention
Cherry branches are divided into developmental branches and fruiting branches. There are many developing branches on the young tree. The leaf buds in front are elongated and grow, expanding the crown, and the axillary buds in the lower part produce fruiting branches. After entering the fruiting stage, most annual branches are called fruiting branches, with terminal buds outside leaf buds and axillary buds mostly flower buds. Results Branches were divided into long fruit branches (15 ~ 20cm), middle fruit branches (5 ~ 15cm), short fruit branches (about 5cm) and flower cluster fruit branches (1 ~ 2cm) according to length. Judging from the fruit-setting ability, the fruit-setting ability of long fruit branches is poor, generally around 40%; The fruiting ability of intermediate fruit branches varies with varieties; Short fruit branches have high fruit setting rate and good fruit quality; The fruit branches of flower clusters are the main fruit branches of flourishing trees in full fruit period, and the fruit setting rate can reach about 80%. The fruit has the best quality and long life, and can bear fruit continuously 10 ~ 20 years. Fruiting branches and flower cluster fruit branches are the basis of yield formation. In China cherry and sour cherry, the proportion of long fruit branches and middle fruit branches is large in the early fruiting stage, while in the full fruiting stage, the short fruit branches and flower cluster fruit branches are dominant.
Pruning of small trees
In order to promote the early fruiting of young trees, on the basis of shaping, the pruning degree of all kinds of branches should be light, mainly in the growth period. In order to control the growth of branches, increase branches and expand the crown. In winter, the pruning time should be postponed until before germination, so as to avoid dehydration and drying of the cut. In addition to cutting short the main branches and extension branches, and properly thinning out some over-dense and cross branches, the other middle branches should be as dense as possible. & gt