Methods and precautions of grafting walnut trees in dog days

1. Variety selection and grafting methods should choose varieties with strong adaptability, good performance, high yield, excellent nut quality, high grafting survival rate and rapid molding, such as Xiangling, Luguang and Linzhong No.1.

1. Hard-branch scions (used for branch grafting in spring) should be collected 20-30 days before germination, and branches with small pith, full branches, full buds and no pests and diseases should be selected. Scions can be stored by sand storage technology.

2. The scion used for green branch grafting (bud grafting) is used at harvest. During long-distance transportation, protective measures should be taken to prevent water loss and avoid rubbing wax layers and buds. Scions must be used up on the same day.

Second, the grafting time

1, and the suitable grafting time is from early April to early May. Because this technique is not easy to master and the survival rate is not high, it is not recommended to apply this method.

2. The best time for bud grafting is from mid-May to late June. At this time, the temperature and humidity conditions are suitable, and the roots and ears are growing vigorously. After grafting, callus is easy to form, buds grow quickly after germination, and the degree of lignification is high, which is conducive to safe overwintering.

Third, the grafting method adopts square bud grafting, and the operation points are as follows:

1, rootstock treatment to remove too dense and redundant branches, the whole tree. Select branches with the thickness greater than 1cm, select the grafting position within the range of 1cm from the main branch (to make the tree compact), and then leave 4-5 leaves at the top of the branches to remove the top, flexibly control the budding direction, with the central stem bud inward and other lateral branches facing one side or the back of the branches, which is beneficial to restoring the tree shape.

2. Take buds, and select the buds on the mature and full scion with the thickness similar to that of the rootstock. When taking buds, when the upper part is about 1 cm away from the bud body, cross-cut it back to the original cutting direction, and then push the bud body to the other side at the fracture of the tear side, so as to separate the xylem from the phloem of the bud piece and ensure that all the growing points are removed. Finally, tear off the bud by hand.

3. Graft on the rootstock to be grafted, select a smooth part with appropriate position and direction, and draw a knife according to the size of the bud piece. Cut longitudinally (the length is about 2 times longer than the bud, which is beneficial to release water), then cut horizontally and tear off the phloem. The removed part is about 0.2 cm longer than the length and width of the bud. Then put the picked bud into the rootstock, and make sure that one horizontal and vertical edge of the bud is aligned with both sides of the rootstock. Finally, the buds are tied tightly with elastic plastic strips from bottom to top to ensure that the buds are in close contact with the cambered surface of the rootstock, and there is no windward place.

Fourth, post-management

1, sprout removal, rootstock cutting and unbinding, all sprouts on the grafted rootstock are removed, and leaves are left to prevent the buds from directly drying up and affecting the survival rate; When the grafted bud grows to 5 cm, it enters the cutting anvil and cuts off the part above the grafted bud; Unbind the grafted buds when they grow to 15-20 cm (when the buds heal), and continue to accelerate the germination after unbinding.

2. Fertilizer and water management After grafting, strengthen fertilizer and water management according to soil moisture. When the soil water deficit is not serious, do not water and fertilize within 2 weeks after grafting. When the new shoots grow to more than 10 cm, topdressing and watering should be done in time, or topdressing, irrigation and weeding should be combined. In autumn, phosphorus and potassium fertilizers should be appropriately increased to prevent seedlings from growing in vain. In the growth period of new shoots, it is necessary to check in time and pay attention to prevention and control.