There are three purposes of pruning adult trees: one is to adjust the size of a year, and to thin out some fruit branches in the new year to ensure that the fruits are nutritious; The second is to keep the tree round and remove the vertical branches; The third is to make the canopy density appropriate and ensure good sunshine and ventilation.
(1) Pruning season
Apple trees should be pruned in winter, and basically all the leaves will fall off.
(2) Pruning of young trees
Young tree pruning should be carried out according to the principle of "giving priority to lightness, paying equal attention to modeling and results, and promoting early yield increase"
2 ~ 4-year-old young trees, under the premise of arranging backbone branches, the key point of pruning is to clean up a layer of tightly squeezed branches and straighten the tree shape. According to the planting density, small crown sparse layer shape (less than 80 plants per mu) and free spindle shape (more than 80 plants per mu) can be popularized. Small crown and sparse layer shape: select 3 ~ 4 main branches in the first layer, clean the dense branches that affect the growth of main branches after selection, and clean 1 ~ 2 branches every year, and strive to clean them up in 2 years. Free spindle shape: choose 3 ~ 4 small main branches every year, with the spacing of main branches about 20 cm, and properly remove the branches that are too dense.
Young trees of 5 ~ 8 years old have entered the fruiting period, and the key point of pruning is to clean up the dense branches between layers, improve the lighting conditions of the trees, and make the fruiting parts gradually transition to the backbone branches. Clean up 2 ~ 3 crowded places every year, and strive to clean them up in 3 years. After several years of adjustment and cleaning, five main branches, 1 ~ 2 auxiliary branches and 10 ~ 13 main branches were retained in the sparse layer shape of the small crown.
(3) Pruning of adult trees
The pruning of adult trees aims at "increasing light, raising branches, stabilizing quality and increasing yield". The pruning focuses on thinning out the large auxiliary branches, large lateral branches and large branches in batches, so that the large branches remaining above the second floor extend outward as far as possible, and the total number of branches accounts for less than 20% of the total number of branches in the village, which is beneficial to the illumination of the inner room on the first floor. If the crown is high, it should be pruned gradually according to the strength of the tree, and the height of the tree should be controlled below 3.5 meters; If the crown has been crossed, the peripheral densely packed branches should be drained or transformed into small branches, and the branches should be shortened to slow down the outside and promote the inside, or the direction and angle of the main side branches should be changed by changing the main branches, so that the crown group can be kept at about 1 m, so as to improve the lighting conditions of the population and individuals.
(4) Cut off diseased branches and insect branches.
According to the investigation, many diseases and insect pests of apple trees overwinter on branches. For the diseases and pests that overwinter in trees, combining with winter shears, all branches of diseases and pests are cut off, burned or buried deeply, which can obviously reduce the harm in the coming year.
(5) Scrape the rough old bark.
A large number of overwintering bacteria and pests often lurk in the gaps between the thick old bark and trunk of fruit trees. Scraping rough old bark, burning or burying it deeply has a good control effect on many kinds of pests and diseases, and sometimes even completely eliminates some pests.