How to prune and train hawthorn trees

The pruning and training of hawthorn trees is a management measure of reasonable adjustment carried out on the basis of soil, fertilizer, and water management, and is an important technique for promoting high yields of hawthorn.

1. Training

The high-yielding tree form of hawthorn varies according to cultivar, site conditions, planting density, and planting method. The key to a high-yielding tree form is whether it can make maximum use of space to achieve fruiting in three dimensions. Based on the characteristics of hawthorn, such as a strong trunk, obvious layer structure, and strong light preference, the central leader with scaffold layers form and the natural open-center form are suitable.

The main characteristics of early high-yielding tree forms are: First, low trunk. The trunk height is set at 40-60 cm, which allows rapid canopy expansion, a large number of branches, fast thickening of trunk circumference, and early fruiting. Second, low canopy. The canopy diameter is controlled at about 3.5 m, the tree height is 3-3.5 m, and 55-111 trees are planted per mu. This makes full use of land and light to increase yield per unit area. Third, few main branches, few lateral branches, and many branch groups. There are 3-5 main branches, each with 2-3 lateral branches. The main branches extend upward at an angle, making full use of the branches on the underside for fruiting. Each lateral branch should have an appropriate number of auxiliary nurturing branches and fruiting branch groups directly attached. The canopy structure is compact, with good ventilation and light penetration, and bears fruit both inside and outside. Fourth, the distance between layers should be large. For hawthorn trees, the distance between layers is best at 1.2-1.5 m, using branches in the inner canopy and the transition zone in the middle and rear portions to form flower buds and set fruit.

2. Pruning

1. Training and pruning of young trees. The main characteristics of the young tree stage are that within one or two years after planting, growth is relatively small and growth vigor is weak; this is the replanting recovery stage. Pruning at this stage is mainly for training. Pruning methods are used to select and retain well-developed scaffold branches at all levels, open up the angles of the scaffold branches well, and lay the foundation for developing a high-yielding tree structure. When pruning, the methods of “promote first, then slow down” and “combine winter and summer” should be adopted. The pruning principle should be: for 1-3 year old young trees, all branches should be moderately to heavily headed back, with more cutting and no thinning, so that they produce many vigorous branches, rapidly expand the canopy, and then flower-forming measures are taken to achieve early fruiting. The key points of pruning at this stage are: moderately head back the main and lateral branches; for moderate-growing parallel branches, lightly head them back if there is space, to increase branching and expand fruiting positions; if there is no space, do not cut and leave them to grow slowly to bear fruit earlier. Properly thin out branches that are too densely grown or that compete with scaffold branches.

2. Training and pruning of trees in the initial fruiting stage. In addition to building a good tree form, pruning at this stage also requires cultivating various types of fruiting branch groups, so that the tree gradually transitions from a certain yield to the full fruiting stage. Pruning is mainly thinning and cultivating fruiting branch groups. When auxiliary nurturing branches conflict with scaffold branches, the auxiliary nurturing branches should be dealt with promptly to make way for the scaffold branches. Retained strong, upright branches should be pulled flat and left to grow slowly so that they bear fruit early. Branches that have borne fruit for more than two consecutive years should be retracted in time to prevent the fruiting position from moving outward. Competing branches that have space can be cultivated into fruiting branch groups, while those that are too dense can be thinned out.

3. Pruning of trees in the full fruiting stage. Continue to cultivate and refine the tree form, improve the unit composition of the leaf canopy, adjust the surface condition of the exposed leaf canopy, cultivate and renew fruiting branch groups, overcome the phenomenon of alternate bearing, strive for high, stable, and high-quality yields, and extend the number of years of the full fruiting stage. Measures such as heading back, retraction, branch thinning, summer pinching, and flower cluster thinning should be adopted for fine pruning. Maintain the ratio of fruiting branches to vegetative branches at 2:3 or 3:2. Thin out or retract and rejuvenate fruiting branch groups. The peripheral branches should be headed back and flower clusters thinned to strengthen vegetative branch growth. Thin out overly dense branches, overlapping branches, crossing branches, and parallel branches.

4. Pruning of trees in the fruiting renewal stage. During this period, tree vigor clearly weakens, scaffold branches begin to droop, the inner canopy becomes bare, and water sprouts emerge in large numbers. However, hawthorn trees are relatively easy to renew and rejuvenate. As long as soil, fertilizer, and water management are strengthened, together with pruning measures, tree vigor can be restored and the fruiting years extended. Generally, scaffold branches at all levels are retracted year by year, and water sprouts are used to rebuild fruiting branch groups.