Juvenile state refers to the period from survival after colonization to flowering and fruiting, usually 3-4 years. The main task of this stage is to cultivate the tree skeleton and lay a good foundation for high yield in the future. The principle of pruning young trees is light pruning, less thinning and more branches. The greater the amount of branches and leaves, the more organic nutrients are produced, the faster the formation and the earlier the fruiting period. To this end, the following pruning measures are mainly taken.
The extension branches of the main branches are cut off in the short and medium sections to promote the growth of long branches and expand the crown. In order to quickly expand the crown, young trees are multi-branched and multi-leafed. When pruning in dormancy, the method of medium and short pruning should be adopted, and the cut buds should be left on the full buds to facilitate branching in appropriate parts. Sweet cherry has the characteristics of strong polarity, strong germination ability and strong branching ability. After short cutting, 3~5 long branches grow under the incision, forming so-called three branches, four branches and five branches, and most of the others are short branches or leafy branches, which makes the periphery crowded and the middle and lower parts empty. Therefore, these long branches under scissors should be handled according to the situation. The upright branches pumped vertically downward can be cultivated into compact fruiting branches by forced coring in summer or extremely heavy short pruning in the second year of dormancy, and then thinned when a large number of fruits are weak. This not only solves the problem of too dense peripheral branches, but also cultivates fruit-bearing branches and makes young trees bear fruit early. Other branches growing horizontally and obliquely can be treated with slow release, light short cutting and medium short cutting respectively, so as to achieve the purpose of pruning with light cutting, less thinning and more branches.
The upright branches on the back have strong growth potential, and if they are not treated, they will easily become competitive branches and disturb the tree shape. In other fruit trees, thinning is generally used. On cherry, it can be cultivated into a compact fruiting branch group close to the main branch by extremely heavy cutting, or it can be cultivated into a uniaxial fruiting branch group after its base is twisted flat.
Generally, weak branches tend to grow slowly, with few branches and easy uniaxial elongation, which not only hinders the growth of other branches, but also tends to weaken and die. Therefore, small fruit branches should be cultivated by pruning to prolong their life and give full play to their production potential. The first is young and short branches, the first is medium and long branches, and the rest are foliage branches; In the second year, the middle and long branches at the top are cut short, generally only one long branch or middle branch is issued, and the rest are short branches; In the third year, only short and medium branches are cut, and the rest branches are slowly released to promote their early fruits.
2. Pruning of trees in full fruit period
Under the normal management and pruning measures, the first fruiting period is 2-3 years after the young age, and it will enter the full fruiting period when it is 6-8 years old. After entering the full fruit stage, with the expansion of crown, the increase of branches and leaves and yield, the tree vigor tends to ease, and the vegetative growth and reproductive growth are basically balanced. The main task of pruning in this period is to keep the tree robust, maintain the fruiting ability of fruiting branches and prolong its economic life.
After a large number of sweet cherries bear fruit, with the growth of tree age, the tree potential and fruiting branches gradually weaken, and the fruiting parts are easy to move out. At this time, in addition to strengthening the management of soil, fertilizer and water, we should also adopt thinning, shrinking and new pruning methods to maintain the moderate growth of trees. Whether the main branches and fruiting branches continue to slowly release or retract mainly depends on the growth and fruiting ability of the following fruiting branches and fruiting branches. If the later fruiting branches and fruiting branches grow well and have strong fruiting ability, we can continue to choose strong branches to extend in the periphery; On the other hand, if the later fruiting branches and fruiting branches are weak and the fruiting ability begins to decline, they should be retracted. The application of release and contraction must be moderate, so that the retraction is not strong and the release is not weak.
After entering the full fruit stage, the tree height and crown size basically meet the plastic requirements. At this time, it is necessary to turn around and be happy in time, and do not continue to cut the trunk extension branches to prevent the orchard group from being too large to affect ventilation and light transmission. The upper branches and peripheral branches that may disturb the tree shape and affect the ventilation and light transmission conditions should be drained or shrunk.
The fruiting branches of cherry are easy to weaken after a large number of fruits, especially the uniaxial extension branches, the lower branches of main branches and the drooping branches. Branches that have completely aged and lost their fruiting ability or are too dense can be thinned, and those with vigorous branches and full buds at the back can be retracted and rejuvenated. In the full fruit-bearing period, trees must carefully prune the fruiting branches to match the fruiting branches, vegetative branches and preparatory branches, so as to maintain vigorous growth and high and stable yield.
3. Pruning of old trees
After the cherry tree entered the aging stage, its growth potential, yield and fruit quality decreased obviously. At this time, annual renewal and regeneration should be carried out in a planned way. Taking advantage of the characteristics of long life and easy germination of latent buds of cherry trees, the branches were collected in batches after harvesting. After the big branches are retracted, a small number of sprouting strips will generally germinate at the lower part of the wound. Choose 1~2 sprouting strips with proper direction and angle to replace the original weak main branches, deal with the remaining sprouting strips, and erase some sprouting strips at the over-dense places as soon as possible to promote the renewal of sprouting strip length. When the reserved sprout grows to 20 cm, it is necessary to remove the heart, promote its branching, and restore the tree vigor and yield as soon as possible. If some backbone branches are only weak in the upper part and strong in the middle and lower part, they can also be retracted to the strong branches for renewal. In the second year of regeneration, according to the strength of the tree, slow release is the main method, and the remaining backbone branches are appropriately shortened to make the tree recover quickly.