Trilogy of improvement of Walnut trees of fixed formation Age by truncation and Renewal grafting

Walnut tree improvement

Step 1: truncate the update.

For large walnut trees that need to change excellent varieties, the tree shape is designed according to specific conditions. The big branches of the whole tree are designed to be tree-shaped, which are removed useless from the base, and the stakes needed to be cut off are used to stimulate the germination of latent buds, and permanent elongated buds and temporary spare buds are selected according to shaping.

The best period of cutting off stem is before sprouting in early April. In this period, the tree has less bleeding and strong irritation, which is beneficial to wound healing and latent bud germination. The series of cutting and retaining piles should be simple rather than complicated. The medium big tree should be above the first main branch, the central trunk should intercept 60 cm, and the first main tree should intercept 50cm. If the tree is tall, it should be above the second main branch, the central trunk should intercept 30cm, the second main branch should intercept 20 cm, and the first main branch should intercept 50cm. All sections should be scraped flat and wrapped with film to prevent dry cracking of the section and promote healing.

After cutting off the dry, select the anvil bud in time. That is to say, there is one bud on each side of the upper part of the central trunk, one extension bud on the back of the main branch pile of the second layer, and one spare bud on the side of the main branch pile of the second layer, and one extension bud on the back of the main branch pile of the first layer, one lateral branch bud on one side and one spare bud on the other side. Especially in the parts where the branches are missing, the empty buds must be left. The rest are not erased with buds to reduce nutrient consumption. When the selected elongated buds and spare buds grow to 20cm, they are coring for grafting.

Step 2: grafting and replacement.

Excellent walnut varieties were selected according to local conditions, and grafting was carried out in July of the year of stem cutting and renewal or June of the following year. Grafting method: those who are proficient in operation are grafted with square buds, and those who are not skilled are grafted with I-shaped buds. It is best to use two woodworking cutting plywood blades, with a rectangular block with a width of 3 cm and a thick 2cm in the middle, and a self-made double-edged bud cutter, which can not only be fast, but also ensure that "opening the interface and cutting the buds" is equidistant from top to bottom. No matter which kind of grafting, the remaining anvil is grafted at one time, and the interface must be in the direction of the grafting. After being connected, the transparent film strip which is wider than the interface is used to wrap it tightly, which can promote survival.

After that, the management should be strengthened, and those grafted in July of that year should be prevented from sprouting. After grafting, only pick the rootstock, do not move other branches and leaves, do not cut the rootstock, do not remove the film, the next spring sprouting, then cut the rootstock, remove the film. For the grafting in June of the following year, it is necessary to promote the control before and after the grafting, so as to make the grafting not only have growth, but also survive the winter safely. Therefore, after grafting, leave 3 compound leaves above the interface, cut off the rootstock, 10 days later, check the survival, cut off the compound leaves, and erase other buds at any time, concentrate nutrients to promote bud germination. When the film is drilled to 10cm, cut off the rootstock, remove the film, promote the rapid growth of grafting, and excise the heart in late August to control the growth and height and strengthen the development of the lower part. In addition, although the walnut has a stronger joint and a firm interface, the amount of new grafted leaves is heavier than that of other fruit trees, and the tuyere at the top of the mountain still needs to be tied with sticks to prevent wind break.

Step 3: positioning and plastic surgery.

In the third year of stem-cutting and regeneration, the new grafts grew to 80cm, and the early-bearing varieties began to bear fruit. It should be positioned and reshaped in time to promote crown speed to restore yield. Specific methods: after leaf spreading in spring, a strong erect extension branch was selected on the central stem to leave 80cm short, to promote the second or third layer of the main branch, and the other branch was drawn horizontally as an auxiliary fruiting branch. The elongated branch of the second layer leaves the 60cm truncated to promote the second lateral branch. The lateral branches are extended and the branches are not cut and released slowly. When the extension branch is damaged, pull the nearby spare branch to the extension direction instead of the extension branch. The rest of the temporary spare branches are put on hold so that they can bear fruit earlier. The growth of branches is more flexible in summer, so measures such as distinguishing, pulling and falling can be adopted to adjust the azimuth angle of the main and side branches.

The following summer, continue to adjust the azimuth of the main and lateral branches, select the second or third layer of the main branch on the central branch, and sparsely cut the remaining branches from the base. The extended branches of the main branches of each layer are released slowly, and the lateral branches are cut short at the full buds to promote branching. Temporary spare branches, affecting ventilation and light transmission and thinning of backbone branches from the base, no effect on retention. At this point, the construction of the new tree skeleton crown is basically completed. Within the next two or three years, except for continuing to adjust the angle, thinning the useless branches and controlling the back branches, all the branches were released slowly and allowed to grow and bear fruit naturally. The temporary spare branch has completed its mission and should be dealt with as appropriate. It should not be allowed to become a door branch and affect the normal growth and fruit of the front branch.

Practice has proved that by using the three-step method, not only the old branches of large walnut trees can be renewed, but also the varieties of walnut trees can be improved, and the irregular tree shape can also be reasonably modified. Taking the grafted varieties such as Qingxiang and Zhonglin No. 3 as an example, the fruit can be seen in the third year, the fruit will be full in the fifth and sixth year, and the annual output value is more than twice as much as the original.