A New Method of High Grafting Walnut

At present, most of the walnuts cultivated in a large area are fruit trees. These trees have mixed populations, serious species degradation, low yield and poor quality. By using the method of high grafting and replacement, the yield and quality of early bearing walnut varieties could be significantly improved by 1-2 years after high grafting and 2-3 years later.

First, the high pick-up period. There are differences due to different climates, and the appropriate high grafting period can be chosen according to the local phenological characteristics of walnut. In view of the fact that the high grafting of walnut is mainly branch grafting, it is generally mastered that the buds of rootstocks sprout to the first development of leaves, generally in February in the south and from late March to mid-late April in the north. However, scions must not be picked and cut after germination, so they should be picked and cut early.

Second, the scion should be picked and cut early. Scions should be collected from excellent varieties, such as Wen 185, Liaohe 1, Xiangling, thin shell incense, Bofeng, Xiluo 3 and so on. Taken from the middle or basal segment of the robust developmental branch, the diameter is more than 1 cm, and the pith is small, smooth and disease-free. The suitable time for ear harvesting is from the defoliation to the middle of February of the following year. Each scion retained 3 full buds, sealed with 95-100 ℃ paraffin wax, tied up 50 or 100 according to variety, buried with wet sand or wet sawdust, thickness 15-20 cm, stored less than 10 ℃.

Third, grafting method. The rootstock should select 5-25-year-old strong trees or inferior varieties, saw the joint according to the original crown affiliation 7 days before grafting, and the saw head should be 20-30 cm from the base. At the same time, at the base of the trunk 20-30 cm from the ground, spirally drilled three or four saws, up to about 1 cm of xylem, to facilitate the flow out. If there is too much bleeding, you can also saw 1-2 more orifices at the base of the joint. When grafting, saw off the dry layer of the rootstock, then cut off the outer skin of the rootstock with a long tongue, cut the scion to grow 5-6 cm tongue-shaped cutting surface, and pinch away the cortex and xylem of the tongue-like part with your hand, and then insert the ligulate part of xylem into the cortex and xylem on one side of the cross-section of the rootstock, so that the tongue-like skin layer of the scion is applied on the tongue-shaped cutting surface of the rootstock cortex, and finally tightly bound with plastic straps.

Fourth, post-management. 25-30 days after grafting, the scion germinated one after another and grew rapidly. When the new tip grows to 20-30 cm, a stick should be tied to prevent the wind from breaking, and the sprouting tillers on the branches should be cut off at any time; if there is no surviving scion, 2-3 should be selected and 2-3 should be sprouted on the anvil pile and budded from July to August. 60 days after grafting, the survival rate was checked and the bindings were removed. In late autumn or early spring, combined with collecting scions, the scion branches grafted on the rootstock were pruned properly. At the same time, we should strengthen fertilizer and water management and pest control after grafting.