Problems and solutions in apple tree pruning

Problems and Solutions in Apple High Spindle Tree shaping and pruning

Apple cultivation in Fengxiang County is mainly dwarfing interstock and double dwarf cultivation. The cultivation forms of these two types of apples adopt the method of dwarfing and dense planting, with row spacing of (1.0-2.0) m × (3.5-4.0) m, and 83-190 plants per mu. At present, most of the apple dense planting orchards use high spindle tree shape, some begin to cultivate after planting, and some are transformed from the old tree shape (small crown sparse layer shape, free spindle shape, slender spindle shape, etc.). High spindle tree shape plays an important role in preventing and alleviating canopy closure, promoting early fruit yield and simplifying management in densely planted orchards. However, there are still many problems in the application of high spindle. In order to make the high spindle tree shape play a better role in production, the seedlings are too weak and the fixed stem is too low; the main branch is too thick and the central stem is too thin; the opening angle is small, leaving the main branch too thin; thinning branches are too light, and the renewal is too late. The author makes an investigation and research on this, and puts forward some solutions.

1 the shaping goal of high spindle tree

The number of branches retained per mu of mature trees is 70,000 ~ 80,000, the ratio of long, medium and short branches is 1 ∶ 3 ∶ 6, the leaf area coefficient is 2.5 ∶ 3.0, the ratio of branch to fruit is 4 ∶ 1, the ratio of leaf to fruit is 30 to 40 ∶ 1, the ratio of flower bud to leaf bud is 1 ∶ 3 to 4, the number of fruit retained per mu is 14000 to 15000, and the coverage rate of orchard is about 70%.

2 Technical parameters of high spindle tree shape

The height of the tree is 3.2 to 3.5m, the dry height is 0.91m, the thickness ratio of the central leading stem to the main branch is 5 ∶ 1 (2 ∶ 1 in the first year of shaping, 3 ∶ 1 in the second year, 4 ∶ 1 in the third year, and 5 cm 6 ∶ 1 after shaping), the maximum thickness of the base of the main branch is less than 3 cm, and the main branch is rotated year by year. The central trunk is equipped with 30-40 small main branches, the horizontal length of the main branch is not more than half of the plant distance (0.5-1.0 m), the upper and lower main branches are slightly shorter, and the middle main branches are slightly longer; the angle between the main branches and the central trunk is about 110o, which is mainly determined by the growth of the cultivated varieties, the strong growth angle is more than 110o, and the weak growth angle is less than 110o; the main branches directly bear fruit branches and small fruit branches, and the whole tree is spindle-shaped. After adulthood, the crown width is small, the number of branches is sufficient, the fruiting ability is strong, there is no large main branch, the light is abundant, and the light energy utilization efficiency is high (figure 1, figure 2).

3 existing problems and solutions

3.1 the seedlings are too weak and the fixed stem is too low.

Judging from the reality and current situation of raising seedlings in China, domestic apple seedlings are basically two-year-old fast-growing seedlings or three-year-old seedlings, which are too small and weak compared with foreign apple seedlings, some are more than 1.5 meters, and some are less than 1 meter. This will inevitably lead to low drying. It is suggested that seedling enterprises, cooperatives, seedling farmers and family farms should cultivate large apple seedlings with branches (figure 3).

Fig. 3 large seedlings of dwarfing rootstock

3.2 the trunk is thick and the central trunk is too thin

This phenomenon is mainly reflected in the transformation into high spindle-shaped orchards, and there are also individual orchards that cherish branches. The main reason is to cherish the branches, cherish the fruit, do not want to remove the big branches, or some fruits are unwilling to go to the branches, not renewed in time. The solution is to update the main branches with a thickness of more than 2.5 cm or small fruiting branches with a thickness of more than 2 cm and a length of more than 35 cm, leaving some fine main branches and small fruiting branches in orchards with a high spindle-shaped tree. and the number is not too much. Updates should be carried out year by year and should not be achieved in one step. The method of renewing the main branch: (1) remove the overdense and oversized main branch directly, do not hurt the central trunk, and intercept the small diameter of 1.5 cm (figure 4); (2) if the main branch is too large, there is space around it, the main branch should be injured first, and then thinned after sending out new branches (figure 5), and be treated according to the situation.

Fig. 4 update main branch fig. 5 renew after injury and new branch

3.3 the opening angle is small, leaving the main branch is too thin

Although it was cultivated and reformed according to the high spindle tree shape, the angle of the main branch was too small to meet the standard of the high spindle tree shape, some left too few main branches (figure 6), lack of branches in the crown, abundant light, but the yield was too low. Solution: increase the angle of the main branch, use the method of strong pulling branches or three saws to open the angle (figure 7); the method of sprouting is used to cut the missing branches of the crown or the method of drawing a saw deep into the xylem with a hacksaw blade at the upper 5mm of the bud eye to make new branches.

Fig. 6 there are too few main branches in the crown

Fig. 7 modified high spindle tree

3.4 thinning is too light and updating is too late

Branch thinning is too light, renewal is too late, cherish the fruit to make the main branch grow too thick and too large, some lose fruiting ability, some fruit parts move outward, the yield is low and the quality is poor. The solution is to renew in time when the thickness of the base of the main branch grows to 2.5 cm, replace the new with the old, stabilize the yield, and achieve the goal of high quality and high yield.