31/05/2019 • CultivationPruning of the bushy-vase hazelnut tree

With this basic guide we will describe you how to carry out pruning of the hazelnut tree in its bushy-vase shape.

The bushy-vase is the training system that makes the vegetative development needs of the plants coexist with those of the farmer’s operating techniques.

It is a system planted at 30-40 cm above the ground. This allows, as opposed to the bush training system, to easily carry out the operations of suckering and cleaning at the base of the plant.

The Astone planted in autumn is pollarded at 30-40 cm. The following year, chosen 4-5 best-oriented vigorous branches, it is given shape to the vase. 

Why do we have to prune the hazelnut trees?

The hazelnut tree grows in various stems. However, for the hazelnut production, it is better to prune the tree so that it can develops only one main stalk.

The main objectives of the hazelnut tree pruning are:

• establish a balanced rapport between the productive and vegetative activity;
• optimizing the health of the tree by increasing its vigour, developing a solid structure and minimizing the risk of structural failure;
• increase the penetration of light inside the foliage;
• facilitate the hazelnuts picking.

When should pruning be done?

Pruning must be carried out during the dormancy period, which occurs from late autumn to early spring.

Pruning is used to manage the growth of trees beyond the constitution phase and to invigorate older trees.

It is a means of removing sick or dead wood, thus prolonging the life of the orchard. The short branches, 5/6 cm in length, are almost sterile, while, for productive purposes, the best branches are those with a length of 15/20 cm.

Structural pruning

Structural pruning is performed in the first 4 to 5 years after planting and used to encourage a robust tree structure capable of supporting heavy crops and withstanding loads of ice and snow.

Objective:
get a tree in the shape of a single vase with three or five main branches.

1st year

Cut the stalk to a height of 0.8 meters, which will induce the growth of a well-defined crown.

From the 2nd to the 4th year

Select 3-5 primary branches (Picture 1 – Illustration A) using the following criteria:

1. choose primary branches turned toward opposite directions;
2. eliminate the branches at an acute angle (less than 35 degrees) with respect to the trunk;
3. leave a space of about 15 cm between each primary branch;
4. make sure there is only one central stem;
5. cut the lower branches of the tree so that around the first 60 cm of the trunk do not have branches.

During the second winter select 1 or 2 additional scaffold branches (Picture 1 – Illustration B). When the scaffolding selection is complete, pruning can focus on terminal branches to reduce crowding (Picture 1 – Illustration C).

If the trees have a habit of vertical growth, the removal of one or two vertical branches in the middle of the tree in the 4th or 5th year will open the tree canopy.(Picture 1 – Illustration D).

Maintenance pruning

Maintenance pruning is that which takes place from the 5^th year onwards.

Objective:
ensure the strength and the productivity of the tree.

1. remove the water sprouts (small sprouts that arise from the trunk or branches);
2. remove the limbs that cross or that are too close to each other;
3. cut the central branches and shorten the low side ones;
4. prune the lower branches of the tree on the first 60 cm of the trunk;
5. remove the suckers that grow through the foliage in the spring before they harden.
6. make thinning cuts to open the cover so that the light penetrates into all the parts of the tree;
7. remove hanging limbs that interfere with the spraying of herbicides or machine movement. Prune the broken and sick branches.

In the hazelnut grove in production, we have to make return cuts to stimulate the plant to produce new branches.

How to make the cut of the branches?

When you prune, it is always necessary to remember that an operation comparable to the surgical procedure is being applied to the plant. To prevent that infections will develop after cutting, there are some important points you should follow:

1. prune branches so that you don’t leave stubs
2. practice a clean and inclined cut. The cut must be clear, without unnecessary damage and fraying on the branch, also it must not be straight but ideally it must have a 45-degree inclination, this avoids the dwell of drops of water on the cut area;
3. proceed with the disinfection of the largest cuts with appropriate mastics or simply with a copper-based treatment;
4. it is important to make thinning cuts at the branch collar where the branch attaches to a larger limb or the trunk, since hazelnut wood is particularly sensitive to rotting fungi;
5. use clean tools. Shears, saws and loppers must be cleaned, it is also useful to disinfect them between one plant and another to avoid transmitting diseases to the orchard.

Mechanical pruning

In recent years, the difficulty of finding the workforce and the high costs represented by traditional pruning operations are pushing towards a mechanical pruning, even if many aspects remain to be evaluated.

Mechanical pruning is carried out with particular disks assembled on adjustable bars.

The intensity, deepness and direction of the cut can change from time to time, adapting to different situations of intervention. In plants in production, mechanical pruning reduces the overall intervention time, even if it is not exhaustive because it must be preceded and followed by a manual finishing operation.