Walnut tree grafting technology, detailed explanation of walnut tree grafting technology and later management (with photos)

Walnut has always been one of people’s favorite nuts and is also my country’s main exported fruit that earns foreign exchange. At present, walnut trees, as ecological and economic trees, are widely used in converting farmland into forests in hills, mountains, and plains. However, due to immature grafting technology, the survival rate of grafting is low and the cost of grafted seedlings is high. Below I will give a brief introduction to walnut grafting technology. Friends in need can refer to it! Grafting technology of walnut trees:

1. Commonly used grafting methods:

1. Split grafting method: Make a split on the rootstock and insert the scion, so it is called split grafting. Split grafting is a main method of branch grafting in spring.

1) Rootstock cutting. Saw the rootstock at a straight and scar-free part of the bark, smooth the wound with a knife, and then make a vertical split with a depth of 4-5 cm in the middle of the rootstock.

2)Scion cutting. Leave 2-3 buds on the scion, and cut one knife on each side of the lower part to form a wedge shape. Connect the outside of the lower wedge of the scion to the cambium of the stock. The insides are not connected. The scion shaved length is 4-5 cm. The shaved surface should be flat and the angle should be appropriate so that the top and bottom of the rootstock can join the scion at the joint.

3) Join. The key is to align the cambium layers on both sides. It is best to make the cambium layers on the two outer sides of the scion face each other. If you can't align both sides, keep the cambium aligned on one side. Be careful not to insert all the wounds of the scion into the split opening, and expose more than 0.5 cm to facilitate wound healing.

4) Bandaging. For medium or thin rootstocks, insert a scion into the split (preferably seal it with wax), and then tie the joint with a plastic strip 4 cm wide and 30-40 cm long. When bundling, the split and Wrap all wounds and exposed areas tightly and tie them tightly.

2. Double-door budding and single-door budding: When grafting, pry open the bark on both sides of the rootstock incision, as if opening two doors, so it is called double-door budding; single-door budding, just pry open the incision. Bark on one side. Other grafting methods are the same for both. Suitable for varieties that are difficult to graft. After the grafting is successful, it can germinate that year.

1) Rootstock cutting. Make the length of the bud piece equal to the length of the rootstock cut. Cut the rootstock up and down on the smooth part of the bark so that the width appropriately exceeds the width of the buds. Then make a longitudinal cut with an L knife in the center to make the cut appear in the shape of an "I". If it is a single door, make a long cut on one side, deep into the wood. The bark is then pried open to form a double or single door.

2)Scion cutting. Make L knives on each side of the scion bud and take out the square-shaped bud pieces.

3) Join. Put the scion into the cut of the rootstock. For double-door budding, cover the scion buds on the left and right sides. For single-door budding, pry open the rootstock skin and cover the scion buds. The buds should be in contact with the pried-off Close to one side.

4) Bandaging. Use plastic strips 1-1.5 cm wide and 30-40 cm long to tie the bud pieces together to expose the buds and petioles.

3. Square grafting: The bud piece taken during grafting is square-shaped, and a square bark is also taken from the rootstock, so it is called square bud grafting. The square bud grafting contact surface is large, which is more suitable for walnuts whose bud grafting is not easy to survive. It is easy to germinate after grafting.

1) Rootstock cutting. When grafting, first compare the lengths of the rootstock and scion incisions, and mark them with a knife. Then make a cut on the top, bottom, left and right, deep into the xylem, and then use the tip of the knife to pick out and remove the bark of the stock.

2) Join. Place the bud piece into the rootstock incision so that its top, bottom, left and right sides are exactly closed with the rootstock incision. If the scion bud piece is smaller, that's okay: if the scion bud piece is too big to fit in, it will have to be trimmed down to make it the right size.

3) Bandaging. Use plastic strips 1-1.5 cm wide and 30-40 cm long to tie up the joints to expose the buds and petioles.

2. Technical key points of grafting large branches:

1. The quality of scion collection is directly related to the survival rate of grafting. The scion should be selected to grow robustly, fully developed and have a relatively small pith. Small, disease-free and insect-free, developing branches or long branches with a thickness of 1.0-1.5 cm. The scion collection time can be carried out from after the walnut leaves fall to before the sap flows. The scion storage depends on the grafting period.

2. In mid-to-late April, the scion has a longer shelf life and the buds are prone to mildew or germination. Storage of the scion is very critical. The optimal temperature for walnut scion storage is -5°C, with a maximum temperature of no more than 8 ℃.

3. The temperature of wax-sealed walnut scions is required to be higher than that of other tree species. The sealing wax temperature should be controlled at 10-15℃, so that the wax-sealed scions will lose their skin during the grafting process. Not easy to fall off.

4. The rootstock is required to be less than 20 years old, with a strong tree body, a smooth grafted part, and a thickness of 3-10 cm.

5. The best grafting period is from the rootstock germination to the first leaf stage.

6. 2-3 days before rootstock treatment, it is required to inflict wounds on the rootstock and release water to reduce the impact of wounds on the survival rate.

7. The best grafting method is tongue grafting.

8. Control the water after grafting. Within two weeks after grafting, check the joint frequently to see if there is water accumulation. If there is water accumulation, injure and release the water in time.

9. Remove the sprouts after grafting. The sprouting tillers should be wiped out in time to prevent nutrient depletion and facilitate the healing of the grafted site.

3. Technical key points of seedling budding:

1. Grafting time: The best time for walnut budding in Dingzhou is May 20th to June 20th.

2. Scion collection: Select developing branches. After cutting the scion, cut off the leaves 1.5-2.0 cm from the base. When collecting a large amount of scions, sacks should be prepared and the collected scions should be covered with wet sacks at any time to prevent them from losing water.

3. Storage of scions: It is required to collect and use them now. The scions can be stored for up to 3-4 days after collection. Storage method: Bundle the scions and put them upright in a container filled with clean water. The depth of immersion is 10 About centimeters. Cover the upper part with a wet sack and put it in a cool place. If it is stored for a long time, the water must be changed 2-3 times a day. 4. Cut the buds: Make a cross-1 cut at the upper 0.5 cm of the scion and 0.5 cm below the petiole. Cut the phloem with one cut, which requires cutting off the phloem. Then make a longitudinal cut on both sides of the petiole, which requires the depth to reach the xylem. But do not cut off the xylem so that the tender bud pieces can be easily removed.

5. Open the rootstock: Make a crosswise cut on the top and bottom of the rootstock, the length of which is the same as the length of the bud piece, and then make a longitudinal cut on the outside. The depth of the cutter should cut the phloem but not damage the xylem. Then use a water knife to separate the skin of the rootstock from the opening, and then tear off a 0.6-0.8 cm wide skin.

6. Inlay the bud pieces: Remove the cut bud pieces from the scion and set them at the opening of the stock. Be careful not to rub the bud pieces back and forth on the stock to avoid damaging the cambium layer.

7. The binding should be done from bottom to top, tightly and with moderate force.

8. After cutting the anvil, leave 2 leaves on the grafted bud.

9. Cut the anvil twice and wait until the petioles can fall off in about 10 days. When a small number of grafted buds sprout, cut the anvil 1.5-2 cm away from the grafted buds.

10. Remove the plastic strip when the binding buds grow to 10 cm. There are many external conditions and internal factors that affect the survival of walnut grafting. When referring to the technical points of grafting in various places, the local site conditions and climate conditions must be combined to improve the grafting survival rate.

4. Precautions when grafting:

1. Green branch scions are used for walnut field grafting. It is best to pick the scions nearby and graft as you pick. If you need to transport or When storing scions for a short period of time, be sure to keep them moisturized.

2. The grafting site should be selected on branches that are less than 3 years old. The grafting site is too thick and the cortex is too thick, which affects the survival rate.

3. When grafting larger rootstocks, they should be reshaped first and then grafted.

And the bud pieces should be connected to both sides of the branches to facilitate the opening angle and ventilation and light transmission.

4. Fuller leaf buds or mixed buds must be used for grafting buds. Male flower buds cannot be used as scions. When scions are used as shriveled buds, they generally cannot germinate that year.

5. The grafting operation must be rapid and the bandage must be tight.

6. Pay attention to the weather forecast and try to avoid rain after picking up, so as not to affect your survival.

5. Post-grafting management:

1. After grafting: Check for survival in about 10 days. The sign of survival is the loss of petioles or sprouting of buds. If the grafting does not survive, re-graft in time.

2. Removal of buds: Remove the buds on the rootstock to promote the germination of the grafted buds. Generally, the buds are removed once in about 10 days.

3. Cut the stock: After the grafted buds survive, the stock can be cut off about 2cm above the grafted buds to stimulate the growth of the grafted buds.

4. Unbandaging: When the grafted shoots grow to more than 5cm, they can be unbandaged. Untying too early or too late will affect growth.

5. Topping: Topping is done when the grafted new shoots grow to about 30cm to facilitate safe wintering.

6. Insect removal: If insect pests such as woodworms and thorn moths occur, 2000 times of chlorpyrifosicide can be used to eliminate them.

7. Cold protection: Walnut field grafting needs to be winterized and protected from cold in the year of grafting. Before the soil freezes, the soil that can be overwhelmed can be buried to prevent cold. Those that cannot be buried in soil can be wrapped with plastic film and be unearthed or unearthed in time during the germination period in the following spring. Unpack.