El olive graft It is an essential practice in olive growing and fruit growing in general, used to multiply plants, change varieties in adult trees, and take advantage of the specific characteristics of each variety. It consists of inserting a piece of branch or one or more buds (the graft) into another plant, called a rootstock. This technique, refined over generations of farmers, has improved the production, resistance, and quality of olive trees worldwide.
What is a graft and what is it for?
In botanical terms, a graft It is a form of vegetative or asexual reproduction, ideal for ensuring that a new plant has the same characteristics as its parent plant. While sexual reproduction through seeds can generate variability in the traits of offspring, grafting allows maintain genetic varietyThe goal of grafting olive trees is twofold: to take advantage of the rootstock's characteristics (such as vigor, adaptation, disease resistance, and drought tolerance) and to obtain fruit with specific qualities depending on the grafted variety.
For example, a wild olive tree (wild olive) can be used as a rootstock to transmit its robustness and adaptability to the rootstock, while the grafted variety can be selected for the quality of its olives or the oil profile it produces.
Advantages and disadvantages of olive grafting
- Allows quickly change varieties in adult trees, without the need to uproot or replant.
- It facilitates the propagation of selected varieties, preserving its characteristics.
- Allows take advantage of the pattern's resistance in roots and adaptation to the environment, while obtaining a fruit of better quality or greater commercialization.
- Optimizes the use of space and accelerates the entry into production of olive trees.
However, grafting requires technical skill, use of sterilized tools, post-graft follow-up and has a certain risk of failure, since not all grafts take properly.
Plant material and compatibility for grafting olive trees
As important as the technique is selecting the suitable material for grafting. In the olive tree, three types of buds are distinguished:
- Wood buds: They develop into branches and are suitable for various grafting techniques, especially on scions.
- Fruit buds: will lead to the production of olives.
- Dormant buds: can be activated under certain conditions, although their vigor may be lower.
Regarding compatibility, the ideal is to do grafts between plants of the same genusIn olive trees, grafting can be achieved on seed-derived rootstocks (unripe olive trees or wild olive trees) with guaranteed success, provided that both materials are healthy and disease-free.
Types of branches and shoots for grafting olive trees
- 1-year branches: They have clearly visible axillary buds. They are usually used in barb graft due to its vigor and ease of sprouting.
- 2-year branches: They may or may not have produced fruit, they contain axillary buds, but they may have lost some vigor. Suitable for veneer or shield grafts.
- 3-year branches: Smooth, with scars from fallen leaves/fruit and a dormant bud. They are often used in veneer or shield grafts, taking advantage of their greater thickness.
Olive grafting systems and types
The choice of type of graft It depends on the diameter and age of the rootstock and the intended purpose. The main methods are:
Spike graft
Recommended for young small diameter patterns (1-2 cm). A 1-year-old branch with 2-3 buds is selected as a graft. The end is carved into a point, inserted into a groove in the rootstock, and carefully tied with plastic tape or raffia. If the graft is close to the ground, it is covered with soil to retain moisture.
This method is effective for complete renewals and variety changes in young rootstocks. It is essential that the union between the graft bark and the rootstock bark be perfect to promote healing.
Shield budding
Ideal in young plants of 1-2 years or on branches of adult trees between 3 and 6 cm in diameter. Two- to three-year-old shoots, leafless and with dormant buds, are used. The rootstock must be "sap-bound," meaning the bark should come off easily. A T-shaped incision is made, where the shield is inserted with the bud, ensuring contact between the cambiums, and then tied.
This method is simple, can be used for both multiplication and variety change, and can be performed at different times depending on the climate.
Veneer graft
El veneer graft is the most suitable for thick trunks or branches (more than 6 or 7 cm). This allows for more buds to be placed and increases the contact surface, facilitating sprouting. There are two variants: lateral window and central window, depending on how the incision is made and the veneer (bark with bud) is placed on the rootstock. The graft should be tied tightly and uncovered after 21 days.
It is especially useful for renewing mature trees or rejuvenating olive trees with aged branches.
Recommended times for grafting
The ideal time depends on the method:
- Scion graft: Right at the beginning of the vegetative cycle, when the sap begins to flow and the plant is about to awaken.
- Escutcheon and veneer graft: It can be done at the beginning or at the end of the vegetative cycle, as long as the rootstock is "in sap".
In temperate climates, these periods usually coincide with the end of winter or the beginning of spring; in warmer areas, it can extend into summer for the shield.
Preparation of the rootstock and care after grafting
La pattern preparation It is essential for the success of the graft. In young olive trees, it is not essential to remove branches, but in mature rootstocks, the lower branches should be cleaned and a sap strip left behind, which will be removed after the graft sprouts. In old olive trees, it is usual to graft onto the first secondary branches to promote canopy formation and access to light.
Post-graft care:
- Check the bundling (plastic tape, raffia) and remove it after 21 days.
- Spray preventive insecticides against pests on tender shoots.
- Apply healing paste or mastic to protect cuts.
- Stake young shoots to prevent them from being broken by the wind.
- Remove any shoots from the rootstock below the grafting point.
- Monitor watering, avoiding excess moisture.
How to identify a grafted olive tree
- Presence of graft scar (lump or line) on a trunk or branch, indicating the point of union.
- Slight differences in bark color or texture between rootstock and graft.
- Distribution of branches with distinct characteristics (leaves, fruit) from the graft point upwards.
Requirements and key factors for a successful graft
- Compatibility between rootstock and graft (of the same species or genus).
- Healthy plant material, free of viruses or diseases.
- Clean and sterilized tools to avoid infections.
- Contact cambium layers from the pattern and graft to facilitate the formation of new wood.
- Perform the graft in the appropriate season, when the sap flows.
- Protect the cuts and periodically check the progress of the graft.
FAQs
- What benefits does grafting bring to olive trees? It combines the best of two plants: robust roots and a productive canopy, rejuvenating trees and improving adaptation to the terrain.
- What risks are there? If the graft doesn't take, time and materials are wasted. Lack of experience or hygiene can lead to infections or pests.
- Is it possible to graft any variety? There are compatibilities: the pattern and the variety must be of the same gender and be healthy.
- How long does it take to see success? Generally, between 21 days and a month it can be seen whether the graft has healed and is sprouting vigorously.
El olive graft It remains a key technique for modern and traditional olive growing. Changing varieties, multiplying faithful plants, or rejuvenating old olive trees is possible if you are familiar with the types of grafting and their application based on the plant, the season, and the desired objective. With patience, hygiene, and good care, this technique produces healthy and productive trees, perpetuating the quality and diversity of olive groves generation after generation.
