What are the growth characteristics of walnut branches?

  Walnut has strong apical dominance, strong branching ability, weak sprouting ability, and a wide branching angle. Except that the shoots of young trees grow relatively upright, the branches of mature trees generally grow horizontally, with wide branching angles and an open crown. Once the tree enters the full fruiting stage, the branches gradually droop. Walnut branches have two growth peaks each year, forming spring shoots and autumn shoots.

  According to their different characteristics, branches can be divided into vegetative branches, fruiting branches and male flower branches.

  According to their growth vigor, vegetative branches can be divided into developing branches, water sprouts and secondary branches. Both the terminal bud and the lateral buds of developing branches form leaf buds again, and they are the necessary foundation for expanding the crown and forming fruiting branches. Vigorous developing branches readily form mixed flower buds and send out fruiting branches the following year. Most water sprouts sprout from dormant buds (also called latent buds), with long internodes; the leaf axils bear leaf buds, and sometimes poorly developed flower buds, which do not set fruit easily.

Pictured: walnut

  Fruiting mother branches and fruiting branches: a branch bearing mixed buds is called a fruiting mother branch. A branch that sprouts from a mixed bud, bears female flowers and sets fruit is called a fruiting mother branch. The length of the fruiting mother branch varies with tree vigor. The shortest is 5 cm. The longest can reach more than 40 cm. According to length, fruiting branches can be divided into long fruiting branches (>20 cm), medium fruiting branches (10~20 cm) and short fruiting branches (<10 cm), but the length of fruiting branches is often related to variety, tree age, tree vigor, site conditions and cultivation measures. Fruiting branches bear mixed buds, leaf buds (vegetative buds), dormant buds and male flower buds, but sometimes lack leaf buds or male flower buds. Fruiting branches with a length of 10~20 cm and a thickness of 1 cm are the best, with a relatively high fruit-setting rate and a relatively strong ability to bear fruit continuously. The tip of a vigorous fruiting branch can send out a short branch (tail branch) again, and most of these can also form mixed buds in the same year. Precocious walnuts can form, sprout, flower and set fruit in the same year, which are called secondary flowers and secondary fruits. If a fruiting mother branch is allowed to grow naturally, then after several consecutive years of fruiting, its growth tends to weaken, its fruiting ability declines, and alternate-year bearing appears, or it completely loses the ability to bear fruit and finally dries up and dies. Therefore, fruiting mother branches should be pruned appropriately according to their growth conditions, so as to restore growth and improve fruiting ability.

  Male flower branches: the branches are relatively short and weak, generally only 5~7 cm long, sometimes about 10 cm, with very short internodes. The buds are densely arranged; the terminal bud is a leaf bud, and the lateral buds are mostly male flower buds. They mostly occur in the middle and lower parts of 2-year-old branches or in the inner part of old trees. After the male inflorescences fall off, the whole branch is bare except for the retained terminal leaf bud.