Pruning the olive grove: why olive tree have to be pruned
After fertilization, olive trees need to be pruned.
Olive tree bears fruit on branches that are two years old. New fruit branches always grow on the part closest to the trunk: new fruit branches always grow on the part closest to the trunk. A few words to guide all the cuts made on the plant, cuts necessary for its vitality and done at the right time.
There are two types of pruning. The first is re-shaping or training pruning
It is used to shape a young plant or reducing the size of a plant. Reducing the size of an olive tree means working with greater confidence and speed, using mechanical tools, even if limited due to the nature of the terrain. Achieving the current results required the involvement of the Liguria Region and industry associations.
The two most common forms of training are the vase and the multiple-cone vase. In practice, three or four main branches are identified from which the canopy will develop with a well balanced and harmonious appearance. In this case, it is always necessary to allow air circulation inside the canopy, so as to have a prevalence of the foliage on the woody part and that the foliage has the maximum exposure to sunlight. In any case, the less wood there is, the more the fertilizer nourishes the productive foliage.
The second is maintenance or production pruning.
In this case, one tries keep balance growth and the production of fruit. All dead branches, branches pointing inwards and vertical shoots, as well as those towards the apex of the branch are removed, given that they exhaust production capacity. The shoots, in particular, steal nutrition from the plant without producing fruit. They detach easily with a hook cut at the base.
This must be done regularly: in this way, the production of olives will be rather constant.
When to prune?
There is no best time to prune.
There are general rules, also dictated by common sense: don’t make large cuts when there is a risk of frost. Avoid very hot weather, such as late summer, or damp heat, which stress the plant, exposing it to dangerous diseases.
What have we done in the DOP Riviera Ligure olive grove?
We performed a production cut. These are plants that we already re-shaped a few years ago to an average height of about 2.5 to 3 metres. They were given a vase shape. The expert pruner removed the shoots and excess young branches and made a return cut on the end of the branches. The cuts were made with a small, easily manoeuvrable chainsaw (number 25 carving blade), pruning shears and a hand saw. The job took three days.
And the pruning residues?
The pruning waste (branches and foliage) was placed in the centre of the terraces so that they could be passed over with a small tractor equipped with mulcher. This is a tool that chops all the woody parts of the plant.
But it’s not always that easy: in most cases the “fasce” or terraces are so narrow and steep that this can’t be done. The olive-grower must make small piles of branches (the “brotti”) and burn them. This requires paying close attention. You have to work early in the morning rather than late in the evening. The piles must be small, carefully fed and monitored. You have to follow fire-prevention rules. You can’t burn during periods in which a serious fire hazard state has been declared. If you are near woods or houses (less than 100 m), you have to have a permit from the Forest Service.
The basic rules for pruning fruit plants in general
The cuts must be clean without chipping the edges of the bark (so the tools must be very sharp).
Never cut a branch flush with the trunk but leave the collar, i.e.,
the enlarged part where the branch meets the trunk (in this way, the plant has the maximum capacity to heal the wound).
When reducing the size of the plant, make many small cuts: there will always be time to reduce the canopy further afterwards.
It is best to avoid leaving stumps of branch and better to leave tips that allow a fast resumption of growth.
The use of copper…
At the end of each pruning, the trees can be sprayed with a copper-based compound. In the case of our olive grove, we used copper oxychloride dissolved in water and sprayed on the plants using an atomizer. Since it is a micro-nutrient, the copper is absorbed through the leaves. Oxychloride is less toxic than copper sulphate. In any case, it is allowed in organic farming. Copper has a strong fungicide action. It appears to be effective against fungus and bacteria. In the case of the olive tree is useful for diseases such as olive peacock spot (evident on the leaves) and mange. The latter is manifested by abnormal growths on the branches, which then tend to dry out.
Costs (net of VAT)
|Pruning and handling the prunings, 5 days||
|Disposal of pruning residues (two days and two hours)||
|TOTAL (NET OF VAT)||
And in the past?
Looking at the “olive woods” of Liguria, you may note that there are still very tall plants. They aren’t just abandoned trees. They are plants that have not been re-shaped but kept in the “old way”. Until less than thirty years ago, olive trees were managed for height: it was thought that the taller the tree, the more fruit it would produce. The focus was on quantity and not quality. It was an unwritten law. However, tall plants consume fertilizer and require dangerous climbing during the harvest. They do not lend themselves to beating with mechanical tools. In fact, they are dangerous. Every year, someone would die or be irreversibly injured due to this cultivation method. Through the commitment of the Liguria Region and many hours of grower education, it was possible to overcome the tradition. There were the memorable “Lucinasco olive-growing days” in the Imperia valley.
In the past, pruning or trimming was always configured as an art that required the skilful use of tools: small, light hatchets forged by legendary blacksmiths and small saws and hooks.
Of the dried branches, Lucetto Ramella wrote, “we used to save several bundles: when well dried, they were useful in the kitchen for lighting the fire or cooking food. Fishermen often came from the maritime region to fill handcarts. They were used for boiling pine bark and water. They dipped their nets in it to make them stronger”. Today, in some areas, the most beautiful branches are sold as ornamental plants in the flower market.
In the past, in the case of famine, crop failure or war, due to its high heating power, burning olive wood was an extreme measure for a family’s survival.