Key Technical Points and Application Methods of Long-Shoot Pruning in Peach Trees
Long-shoot pruning is a pruning technique that basically does not use heading cuts, and only employs thinning, renewal cuts and long-shoot training. Because heading cuts are basically not used, the current-year shoots after pruning are relatively long, with fruiting branches averaging generally 50-60 cm in length. Long-shoot pruning has the advantages of being simple to perform, saving pruning labor, providing good light inside the canopy, producing excellent fruit quality, helping maintain the balance between vegetative growth and reproductive growth, and making it easy to renew the tree, and it has been widely applied and achieved good results. Long-shoot pruning can be applied in the following 3 aspects.
1. Application to cultivars that mainly bear fruit on long fruiting branches. For cultivars that mainly bear fruit on long fruiting branches, remove the excess slender fruiting branches at the tips of the scaffold branches, as well as vigorous competing shoots and water sprouts, and selectively leave some healthy or moderate fruiting branches for delayed pruning or light pruning, so that after fruiting the fruit suppresses vigor, promoting healthy growth of branches in the middle and rear parts of the scaffold branches, achieving the three-dimensional fruiting goal of “fruiting at the front, growing shoots at the back, not overly vigorous at the front, and strong at the back.” Such cultivars include Okubo, Xueyulu, and others.
2. Application to cultivars that bear fruit on medium and short fruiting branches. First use long fruiting branches with long-shoot training to encourage them to produce medium and short fruiting branches, then use the medium and short fruiting branches to bear fruit. Such cultivars include Shenzhou Honey Peach, Fengbai, Cangfang Zaosheng, Annong Shuimi, and others.
3. Application to cultivars prone to fruit cracking. Use long-shoot pruning to set fruit on the middle and upper parts of long fruiting branches; when the fruit grows larger, the branches are bent down and droop, at which point the fruit growth rate slows and fruit cracking is reduced. Suitable cultivars include Huaguang, Ruiguang 3, Fengbai, and others.
4. Principles for applying long-shoot training or thinning in long-shoot pruning
(1) Branch retention density: retain one fruiting branch every 15-20 cm, with the distance between branches on the same side being more than 40 cm. For example, for mature trees with a planting density of 3 m × 5 m or 4 m × 6 m, retain an average of 150-200 long fruiting branches per tree.
(2) Length of retained current-year shoots: retaining shoots 40-70 cm in length is more suitable. For cultivars of the northern group, which mainly bear fruit on medium and short fruiting branches, the number of long fruiting branches retained should be reduced, and more medium and short fruiting branches should be retained.
(3) Insertion angle of retained current-year shoots on scaffold branches: for cultivars with an upright tree habit, oblique or horizontal branches are preferable. For spreading cultivars, mainly retain obliquely upward branches. For young trees (especially upright types), appropriately retain more horizontal and downward-facing branches.
(4) Renewal of fruiting branch groups: the weight of fruit and foliage can bend and droop current-year shoots, and healthy renewal shoots grow from the base; during winter pruning, cut the fruited mother branch back to a healthy branch at the base for renewal. If renewal shoots have already grown near the fruiting branch group on the scaffold branch, then completely renew that fruiting branch group, using the renewal shoot on the scaffold branch to replace the fruiting branch group.
When using long-shoot pruning, summer pruning should also be carried out in a timely manner, thinning overly dense branches and water sprouts. Also pinch the new shoots growing from perennial branches in the inner canopy to achieve renewal and rejuvenation of inner-canopy branch groups. At the same time, after long-shoot pruning, flower and fruit thinning should likewise be carried out, and the crop load adjusted in a timely manner; this is the prerequisite for obtaining high-quality fruit and for branch renewal.