Garlic

Allium sativum

1. Identification and origin

Allium sativum L. is a perennial herbaceous species of the Amaryllidaceae family, cultivated as an annual. It is known as garlic and originates in Central Asia, having spread widely throughout the Mediterranean, Europe and the remaining continents. The plant is propagated vegetatively through cloves, since it rarely produces viable seeds.

2. Economic importance

Garlic is one of the most important culinary vegetables worldwide, used both fresh and in the food, pharmaceutical and nutraceutical industries. Its economic value derives from the characteristic aroma, the content of sulphur compounds and the associated functional properties. The crop is relevant in intensive systems outdoors and in greenhouses, with high demand for sanitary quality.

3. Botanical characterisation

Herbaceous plant with linear and flattened leaves, of intense green colouring. The bulb is composed of several cloves wrapped in membranous tunics. The flower stalk (when present) is erect and ends in an umbel with small flowers and bulbils. Reproduction is essentially vegetative, through cloves selected for planting.

4. Soil and climate requirements

It prefers temperate climates, with cool temperatures during rooting and higher ones in the bulb formation phase. It tolerates moderate cold, but is sensitive to strong frosts in the early stages. It requires loose, well-drained, fertile soils rich in organic matter, with a pH between 6.0–7.5. Irrigation must be regular, avoiding waterlogging that favours root diseases.

5. Main pests

• Onion fly: Delia antiqua causes damage to the roots and bulbs.
• Thrips: Thrips tabaci causes silvering and reduction of the photosynthetic area.
• Mites: Aceria tulipae can deform leaves and compromise the bulb.
• Nematodes: Ditylenchus dipsaci affects internal tissues and reduces vigour.
• Aphids (Aphididae): sap sucking and transmission of viral diseases.

6. Main diseases

• Downy mildew: Peronospora destructor causes chlorotic spots and grey sporulation.
• Rust: Puccinia allii causes orange pustules on the leaves.
• Basal rots: Fusarium oxysporum f. sp. cepae affects the crown and bulb.
• Botrytis: Botrytis porri causes foliar necroses and rots.
• Post-harvest rots: Penicillium spp. and Aspergillus spp. under inadequate storage conditions.

7. General crop management

It includes the use of healthy and certified cloves, planting in well-drained soils, crop rotation with non-host species, weed control and monitoring of pests and diseases. Irrigation must be moderate and suspended before harvest to improve conservation. Adequate curing and drying of the bulbs are essential to extend shelf life and reduce post-harvest losses.

Bibliographic references

• EPPO Global Database – Allium sativum.
• CABI – Crop Factsheets – Allium sativum.
• Rubatzky, V. E., & Yamaguchi, M. (2012). World Vegetables. Springer.
• Kays, S. J. (2011). Cultivated Vegetables of the World. Wageningen Academic Publishers.
• FAO – Technical documents on vegetable production.
• Brewster, J. L. (2008). Onions and Other Vegetable Alliums. CABI.