When will the walnut trees be pruned? Why not winter cut?

In order to have a high yield of walnut, in addition to the basic management work, it is necessary to prune the walnut to promote the growth of lateral branches, and the pruning of the walnut tree is limited by time, not just if you want to prune it, and it cannot be pruned in winter. When will the walnut tree be pruned? Why can't you cut it in winter?

Spring pruning: walnut buds sprout to full bloom. Spring pruning helps to ease the tree potential and promote flowering and fruiting, mostly for young trees.

Autumn shearing: White Dew-Frosts Descent (upper / 9-upper / 10, half a month after picking fruit to half a month before falling leaves), autumn shearing helps to strengthen the tree potential and promote the differentiation of mixed buds.

Summer shearing: the Beginning of Summer-Lesser Fullness of Grain (after falling flowers to physiological before falling fruit), summer cutting is suitable for trees that are too prosperous and do not bear fruit.

No winter pruning: winter (dormant period) can not be pruned, because the wound caused by winter is very easy to cause bleeding, so that a large amount of water and storage nutrition loss, resulting in tree weakness, and even branches die, affecting the normal growth and fruit.

Pruning method

1. Sawing and forcing branches

Some trees of walnut have hidden buds at the base of branches, and some have hidden buds in the middle and base of branches, so for the parts that have been bare legs, they must be sawed deep into the xylem above the hidden buds in the bare legs in order to force out new branches. The growth of the new branch varies according to the thickness of the base branch and the depth of the sawing, which can be more than 1-2 meters long (this method can be used in the bald part). If the saw is very shallow, it can only grow branchlets less than 30 cm long. with this method, the fruiting branch group can be achieved or new backbone branches can be cultivated in the bare leg. The new shoots forced on the early-bearing walnut can blossom and bear fruit the following year as long as they grow healthily. Some of the hidden buds of the early-bearing trees are mixed buds, which can blossom and bear fruit in the same year, while the new shoots sprouting on the late-bearing trees take 3 years to blossom and bear fruit.

2. Ring saw

For the larger non-backbone branch, the ring saw from the top of the hidden bud reaches the xylem, which can not only weaken the growth potential of the branch, but also make the lower branch grow out of the branchlet to fill the space of the bald position. the effect is similar to that of sawing, but the effect is stronger. The spiral counterpart ring saw is safer, generally, the diameter of the branch is 5-10 cm, and the saw is 10-15 cm. The distance between the two circles is about 15 cm. If the distance is too narrow, the saw is too deep. The branches will die.

3. Pinch branches

The new tip of the inner chamber can press the unsuitable growth direction to the place where there is space before Lignification (June), because the walnut branches are very flexible and the leaves are large and thick, and the branches less than 5-10 cm in diameter are bent downward in summer. The angle can be opened to the desired angle without the need for a stick to pull the rope.

4. Thinning branches

Walnut sparse big branches, it is appropriate to leave an oblique stubble from the base, low inside and high outside, so that some twigs can grow on the outside to supplement the space, not leaving residual piles, otherwise the piles will die into holes.

5. Breaking the top bud

Walnut terminal bud hypertrophy, apical dominance is strong, often form a large terminal bud in the strip run, the branch rate is low. Breaking off the terminal bud before germination or pinching off the tender tip of the young branch before germination can improve the branch formation rate and form a compact fruiting branch group.

6. Cut the tender shoots

Pruning the tender shoots without Lignification in June can make the axillary buds germinate immediately, and the branch group cultured in this way is much better than the short-cut Lignification branch.

7. Change the head and retract

Walnut pruning mainly uses the method of head-changing and retraction, and short cutting is rarely used. if the wound caused by the retraction of the big branch is too large, leave a cut branch on the target branch to protect the wound, or leave a hidden bud under the cut.

8. Annual branches leave protective buds short

The pulp of the walnut branch is hollow, and after the annual branch is cut short, it is often necessary to dry and shrink a section under the cut mouth to make the cut bud grow poorly, so the annual branch should leave another protective bud above the target bud, close to the short section of the protective bud, so that the protective bud can grow into twigs, which not only avoids the dry shrinkage of the cut, but also ensures the growth of the target bud.

9. Three methods of rejuvenation of twigs

After the full fruit period, the annual yield of big trees mainly depends on the continuous fruiting of strong fruiting branches, and the weak fruiting branches can not continue to form mixed buds, so rejuvenating fruit branches in time is one of the ways to strive for high yield year after year. After several years of continuous fruit, the growth of fruit branches will become weak. at present, they are often cut off when they are weak in production, but on the basis of improving fertilizer, water and light, and adopting appropriate pruning measures, weak branches can be rejuvenated in three main ways:

(1) retract the basal branch: if the basal branch of the branchlet is slender and thin, cutting the basal branch from above the place where the branchlet is born can make the branchlet strong.

(2) scratch the basal branch: if the basal branch is thick, it can rejuvenate the branchlet by sawing the basal branch from the top of the branchlet to the xylem.

(3) truncated uniaxial extension of branchlets: some branchlets uniaxially extended forward to form a longer verbena branch, the growth is weak, if the base of the branchlet is more than 1 cm, the hidden bud can be heavily truncated at the base to regenerate new twigs; if the base of the branchlet is a twig below 1 cm, new twigs usually cannot be regenerated from the base after truncation, and can only be rejuvenated by retracting or scratching the basal branch.