Basis and Development Trends of Training and Pruning Walnut Nursery Stock

  1. Prune according to cultivar characteristics. Different cultivars have different growth and fruiting habits, different pruning responses, and therefore different pruning techniques and measures.

  2. Prune according to tree age and vigor. Fruit trees of different age stages have different vigor; different site and management conditions also result in different vigor. The younger the tree, the stronger the vigor, and the lighter the pruning should be; the older the tree, the weaker the vigor, and the heavier the pruning should be.

  3. Prune according to different pruning responses. For the same cultivar, because of differences in shoot type, position of attachment, branch orientation (horizontal or upright), growth vigor, and degree of heading back, the responses after pruning vary; when pruning, corresponding measures must be taken according to these response patterns.

⟦NL>   4. Prune according to site conditions and management level. Under different site conditions, environmental conditions, and management levels, the growth and development of shoots and buds differ greatly, and corresponding pruning measures should be taken according to the specific circumstances.

Image: walnut

  Changing trends in training and pruning

  With the development of production and scientific and technological levels, the timing of walnut training and pruning, pruning techniques, and so on have also changed.

  1. Changes in planting density and tree form. These are mainly shown in the development from standard-size, sparse planting toward dwarfed, dense planting, and in tree form from large-canopy forms toward small-canopy forms, and from multi-order, multi-level tree structures toward fewer-order, fewer-level tree structures; the small-canopy open-center form and spindle form of walnut trees have gradually replaced the previous open-center delayed-open form.

  2. Changes in pruning techniques. These have developed from the cumbersome pruning of the past toward simplified pruning, from heavy pruning toward light pruning, and from the use of pruning shears alone toward the integrated use of knives, shears, saws, chemical growth regulation, and manual techniques such as twisting, pinching off, scoring, ringing, and bending.

  3. Changes in pruning timing. These have developed from the past emphasis on winter pruning and neglect of summer pruning toward pruning in all four seasons: winter, spring, summer, and autumn, with attention also paid to the integrated and coordinated application of pruning techniques.