Pruning in arboriculture

Pruning is a fundamental subject in fruit arboriculture, as it is a prerequisite for good long-term fruiting on the one hand, and for the longevity of the tree on the other.

Trees are complex living creatures. In order to take appropriate and precise action, it is important to understand the physiological rules that govern it. This is so that we can anticipate its behaviour following our interventions.

There is great diversity in the types of pruning practised, depending on the tree, its age, the region and sometimes even the local cultural heritage. As Jean-Baptiste de La Quintinie, the gardener behind King Louis XIV's kitchen garden at Versailles, once said, "Everyone cuts, but few know how to prune". It's a good way of summing up the subject.

This portal describes the essential elements for correctly pruning fruit trees, answering the following questions : why, when and how should you prune your fruit trees ?

Why prune ?

Generally speaking, the ultimate aim of pruning in fruit growing is to achieve abundant, high-quality production.

Clear, consistent crown development increases tree productivity and lifespan, improves fruit quality and makes harvesting easier. Pruning should therefore be carried out at all times to maximise ventilation and sunlight.

Different types of pruning

The table below shows the main types of pruning used in fruit growing:

Type of pruning	Objectives	Principle	Timing
Plantation pruning	Encourage branching of roots and above-ground parts Ensure that the plant starts to grow again Balance branch/root volumes	Remove dead, dry or damaged roots/branches Shorten roots/branches by a few centimetres	This pruning is carried out when the plant is planted.
Training pruning	To avoid mechanical problems (embedded bark, overgrown branches, etc.) Guide the tree towards its future architecture Plan ahead to adapt the tree to its environment	Select 3 or 4 evenly distributed branches to form the future carpenters.^[1] and form a goblet shape Each year, cut back the carpenters on an outer eye, removing around a third of the annual growth Select 2 to 3 branches from each trunk.	Training pruning is generally carried out 3 years after planting.
Maintenance pruning	Maintain good ventilation inside the tree Maintain the supply of light inside the tree	Remove dead wood and broken or damaged branches Remove suckers (especially those on the rootstock) Remove branches that unbalance the tree's habit, those that cross over or point inwards.	Maintenance pruning every 2 or 3 years
Fruiting pruning	Balancing growth and fruit production Renewal of fruiting bodies Limiting alternation^[2]	Remove any old fruit that may have remained on the branches Recognise the fruiting bodies to encourage interesting fruiting branches. Take care to leave at least 3 eyes on these branches. Limit fruit production to what the branch can bear.	Fruiting pruning can be carried out every year.
Regeneration/restoration pruning	(Re)produce young wood Simplify the structure		This pruning is only carried out on a tree that has become unproductive and/or has been neglected. Depending on the volume of branches to be cut, the pruning can be spread over several years so as not to stress the tree too much.

Focus on training pruning^[3]

The training pruning of a young fruit tree is important because it largely determines the life and development of the tree. It must therefore be consistent with the environment and any constraints.

There are a multitude of possible architectures for fruit trees. When choosing a particular shape, the following factors should be taken into account :

The environment : available space, orientation, climatic conditions, constraints (e.g. nearby buildings);
Rootstock strength: Not all shapes are possible with the same rootstock;
Species and varieties: Not all species are suitable for trellising, for example. Another example is that some varieties have a naturally upright or rather drooping habit, which will necessarily have an impact on the shape of the tree.

The first thing to think about is how tall you want your tree to be. There are low-stemmed trees, half-stemmed trees and high-stemmed trees (known as "plein vent"):

	Pruning	Advantages	Disadvantages
Low stem	Height of trunk : 50 cm Mature tree size : 2 to 4 m	Rapid fruiting Fruits are at human height Pruning and care are much easier Picking fruit is easier than with half-stem trees Less space required	The tree does not live as long Low branches can make maintenance difficult (e.g. mechanical mowing) Ecological mowing possible by small animals only (ducks, chickens)
Half stem	Trunk height : 1.2 to 1.5 m Size of adult tree: 5 to 6 m	Long-lived tree High production The branches do not get in the way of mechanical or ecological mowing (limited to small animals, such as sheep, chickens, etc). Pruning, care and thinning are easier than for tall trees Some trees can be harvested by hand	Wait at least 3 to 5 years for the first fruit to appear Average size
High stem	Height of trunk : 2 m Height of adult tree : 8 m and more	Long-lived tree High production The branches do not get in the way of mechanical or ecological mowing. Pruning every three to five years is sufficient	Wait at least 5 years before producing the first fruit The height of the tree makes pruning, treatment and harvesting more complex.

Before pruning

Theoretical prerequisites

Before pruning, it's important to consider the following points :

What is thepurpose of pruning ? What type of pruning (see above) do we want to carry out ?
Whatare the structural elements of the tree (carpentry, among others) ? How do we want to arrange them ?
How will the tree evolve following our intervention ? For a young tree, plan the size of the tree when it reaches adulthood according to its vigour, its location (nearby buildings ? Shade ? etc.) and its growth habit, in order to adjust the cuts to be made as effectively as possible. For an older tree, think about fruiting and the future weight of fruit on the branches.

Practical requirements

Weather

It is essential to prune in dry weather and it is equally important to check that the weather over the next few days is compatible with pruning. Trees should not be exposed to rain or frost after pruning, asthe wounds caused by pruning are potential entry points for disease.

Pruning tools

The main tools used for pruning are common and easily accessible :

Pruning shears : This is a basic tool for cutting branches up to 1 cm in diameter. It can be "anvil" or, more commonly, fitted with a blade and a counter-blade.
A branch cutter (delimber) : Because the handle is longer, it can reach higher branches while developing more cutting power through leverage. It can therefore cut branches up to around 4 cm in diameter.
A tree saw : This cuts branches with an even larger diameter.

To make clean, precise cuts, these tools must be well maintained, clean and disinfected.

Finally, a healing putty can be applied to the wounds to prevent attacks by bacteria or fungi, for example.

How to prune ?

General information about pruning :

Prune the tree from top to bottom.
Make clean, straight cuts.
Start by removing dead wood and damaged or diseased stems.
Remove branches that cross or point towards the inside of the crown.
Prune branches above an outward pointing eye.
Prune branches at a 30° angle above a bud, with the top of the incision on the bud side (to prevent water running over the bud).
When a branch has to be cut close to the trunk, the cut should be made just after the scar bud, neither too close to the trunk nor too far away, otherwise a snag may form ("we prune the whole branch, just the branch !"). It is very important to preserve the edge and the neck of the branch.^[4]
- Here is a special case of cutting a large branch in 3 stages.

After pruning

Tree health

When we prune, we put the physical integrity of the trees to a severe test.

It may be a good idea tocheck on their health in the days/weeks that follow.

Recycling pruning waste

Pruning waste is an interesting source of biomass and can be used very simply on a farm :

Once shredded, this waste can be used in a variety of ways, depending on the quantities recovered :
- As ramial fragmented wood (RCW ) on crops. RCW is considered to be an agradant material whose primary purpose is to restore degraded soils and increase soil organic matter levels. The shredded material should be placed fresh on the crops.
- It can also be added to compost, either as a nitrogenous component for fresh shredded material, or as a carbon component for dry shredded material.
- Finally, dry shredded material can also be used as animal bedding.
The cut branches, used as they are, can be used :
- To make shelters to promote biodiversity^[5].
- To make fascines which, in certain situations, help to reducesoil erosion.

Resources

Cost

Pruning is not an expensive operation in itself. Consider purchasing the basic tools described above if they are not readily available (see Tools for pruning).

In certain situations (physical constraints, for example), you may need to call in a professional (tree trimmer). In these cases, prices depend mainly on the number of trees to be pruned and their height. Prices may also vary from one region to another.

Time

The time needed to prune a tree depends directly on the following factors :

The age of the tree : a young tree measuring 1.5 m does not require the same amount of work as a tall fruit tree 4 or 5 m high.
The type of pruning carried out : considering the number of branches to be cut, a plantation pruning will theoretically be quicker than any other pruning.
The shape of the tree : a trellised tree, for example, will be quicker to prune than a tall tree.
Experience is often the key to efficiency, so an experienced pruner is likely to go faster than a beginner.

Finally, it is obvious that the operation will not be the same size if you are pruning 1, 10 or 50 trees.

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Appendices

References

To go further

Sources

[1] Vergers Vivants - Fiche technique n°7: La taille de formation des fruitiers " haute-tige ". [2023-09-30]

[2] Jean-Luc Coppée, Claudy Noiret, L'arboriculture fruitière en haute tige, une voie de diversification agricole en région herbagère, Les livrets de l'agriculture, page 17

[3] Fédération des agriculteurs du Haut-Rhin - Fiche technique, Initiation aux techniques arboricoles - Taille de formation d'une tige. [2023-09-30]

[:0-4] Horticultural and botanical notebook - Cutting techniques. [2023.09.30]

[5] Fibl - Technical leaflet: Organic high-stemmed fruit trees, page 6

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