Pruning: Pruning is a very important cultivation technique in order to make walnuts bear early, high, stable and reasonable. The pruning period of walnut is different from that of ordinary fruit trees. This is done after the fruit is picked and before the leaves turn yellow. In North China, it is best to prune between "White Dew" and "Cold Dew". Pruning at this time, although the temperature is low, the wound heals slowly, but the nutrient loss is less. Young trees can be pruned early because they have no fruit, and they can start from the "Summer Festival". Spring pruning is generally carried out around the "long summer". It's too late, because the branches and leaves are too big and consume too many nutrients, which is not conducive to the growth of trees.
Pruning of fruiting branches: The top bud of fruiting mother branches of walnut is mixed flower bud, so pruning is generally not allowed. Only the dense twigs, dead branches, diseased branches and overlapping branches are pruned to make them ventilated and transparent, and promote the growth of fully robust fruiting and developing branches. (1) Pruning of fruiting mother branches: robust branches that grow around the crown 1 year are usually fruiting mother branches in the second year, and are generally not cut short. However, if there are too many fruiting mother branches, the crown will be closed, which will affect ventilation and light transmission. Therefore, it is necessary to prune some fine fruiting mother branches appropriately to stabilize the yield and promote the normal development of the tree. (2) Pruning of extended branches: For the 15-30-year-old trees in full fruit, the 1 year-old extended branches extracted from the top of each main branch at the periphery of the crown can be shortened at 2-3 buds below the terminal bud. If the top branch is not full, it can be cut off at the full bud to enlarge the crown and increase the fruiting position. (3) Pruning of long branches: Long branches are mostly germinated from hidden buds on the main branches of the inner room, which are more common in mature trees and aging trees. In the past, many people cut off contacts with the base, which is called "cleaning the room". In recent years, we have begun to use the fruits of long branches. According to the experience of Hebei, Shandong and other provinces, according to the position and growth intensity of the vacant part in the inner chamber, the long branches can be shortened by one-half to one-third where the buds are full, and fruit branches can be formed after cutting for 2-3 years, which can supplement the gap, expand the fruit range and achieve the purpose of three-dimensional fruit.