Olive tree

Olea europaea

1. Identification and origin

The olive tree (Olea europaea L.) is a tree species of the Oleaceae family, native to the Mediterranean region and the Middle East, where it has been cultivated for more than 5,000 years. Its spread accompanied the Mediterranean civilisations, becoming an agricultural and cultural symbol. In Portugal, it is widely distributed, with the greatest presence in the Alentejo, Trás-os-Montes and Beira Interior.

2. Economic importance

The olive tree is one of the most important permanent crops of the Mediterranean, standing out for the production of olives for olive oil and for table consumption. Portuguese olive oil has growing international recognition, driven by modern irrigated orchards and super-intensive systems. The crop also contributes to carbon sequestration, soil conservation and the maintenance of the rural landscape.

3. Botanical characterisation

A medium-sized tree, generally between 4–10 m in height, with an irregular crown and twisted trunk. The leaves are opposite, lanceolate, leathery, with a whitish lower surface. The flowers are small, whitish, grouped in axillary panicles. The fruit is a fleshy drupe, whose colour evolves from green to black according to ripening. The olive tree is a long-lived species, which can exceed several hundred years.

4. Soil and climate requirements

The olive tree adapts well to Mediterranean climates, tolerating hot, dry summers and mild winters. It is drought-resistant, but benefits from controlled irrigation to maximise productivity. It prefers well-drained soils, with a loamy to sandy-loam texture, with a pH between 6.0 and 8.5. It is sensitive to waterlogging and intense frosts, especially in young stages or during flowering.

5. Main pests

• Olive fruit fly (Bactrocera oleae): perforations and degradation of the pulp
• Olive moth (Prays oleae): damage to leaves, flowers and fruits
• Black scale (Saissetia oleae): sap sucking and sooty mould
• Mites (Tetranychidae): chlorosis and reduced photosynthesis
• Olive bark beetle (Phloeotribus scarabaeoides): galleries in branches and trunks

6. Main diseases

• Peacock spot (Spilocaea oleagina): leaf spots and defoliation
• Olive knot (Pseudomonas savastanoi pv. savastanoi): tumours on branches and trunks
• Verticillium wilt (Verticillium dahliae): vascular wilting
• Anthracnose (Colletotrichum spp.): fruit rots
• Root rots associated with waterlogged soils

7. General crop management

Management of the olive tree includes choosing cultivars adapted to the production objective (oil or table) and to the training system (traditional, intensive or super-intensive). Pruning should be regular, favouring the entry of light and the renewal of fruiting branches. Localised irrigation significantly improves the yield and stability of production. Fertilisation should be balanced, with attention to nitrogen, potassium and boron. Control of the olive fruit fly and peacock spot is essential to guarantee quality and productivity. Harvesting is carried out when the fruit reaches the ripening index appropriate to the type of oil intended.

Bibliographic references

• EPPO Global Database – Olea europaea
• CABI – Crop Protection Compendium – Olea europaea
• IOC – International Olive Council: Olive Growing Guide
• Tous, J., et al. (2017). Olive production systems. In: Mediterranean Fruit Tree Crops. Springer
• Ferreira, I. M., et al. (2020). Manual de Olivicultura. INIAV