Flax

Linum usitatissimum

1. Identification and origin

Flax (Linum usitatissimum L.), belonging to the Linaceae family, is one of the oldest cultivated plants, with a probable origin in the Fertile Crescent region and the Middle East. It was domesticated more than 7,000 years ago and is used both for the production of textile fibre and for obtaining oil-rich seeds. The crop later spread throughout Europe, Asia and America.

2. Economic importance

Flax has a dual aptitude:

• textile fibre, used in the production of high-quality fabrics, ropes and composite materials;
• oilseeds, rich in omega-3 fatty acids, used in human food, animal feed and the paint and varnish industry.

The main producers include Canada, Russia, Kazakhstan, China and European countries such as France and Belgium. Interest in the crop has been increasing due to the demand for natural fibres and functional vegetable oils.

3. Botanical characterisation

An annual herbaceous plant, erect, 30–120 cm tall, with a slender and sparsely branched stem. The leaves are simple, lanceolate and alternate. The flowers are generally blue, although white or pinkish varieties may occur. The capsules are globose, containing small, shiny seeds, brown or golden in colour. The root system is taprooted, adapted to well-drained soils.

4. Soil and climate requirements

Flax adapts well to cool temperate climates, with ideal temperatures between 15–20 °C. It prefers deep, fertile, well-drained soils of medium texture and pH between 6.0 and 7.5. It is sensitive to waterlogging and prolonged periods of drought. The crop requires good soil preparation to ensure uniform emergence and fibre quality.

5. Main pests

• Flax aphid (Aphis rumicis): sap-sucking and transmission of viruses.
• Thrips (Thrips tabaci): leaf silvering and reduced vigour.
• Caterpillars (Noctuidae): defoliation and damage to flower buds.
• Weevils (Curculionidae): boring of seeds.
• Nematodes (Ditylenchus dipsaci, Meloidogyne spp.): deformations, necrosis and plant decline.

6. Main diseases

• Flax wilt (Fusarium oxysporum f. sp. lini): yellowing, vascular necrosis and plant death.
• Anthracnose (Colletotrichum lini): dark lesions on stems and capsules.
• Powdery mildew (Erysiphe spp.): white coating on leaves and stems.
• Rust (Melampsora lini): orange pustules and leaf drop.
• Root rots (Rhizoctonia solani, Pythium spp.): damping-off and wilt in moist soils.

7. General crop management

It includes the choice of varieties adapted to the local climate, crop rotation to reduce the pressure of diseases and nematodes, sowing in well-prepared and drained soils, weed control in the early stages and monitoring of pests such as aphids and thrips. Harvesting should be carried out when the capsules reach physiological maturity, ensuring fibre or grain quality.

Bibliographic references

• EPPO Global Database. Linum usitatissimum – pests and diseases.
• CABI Invasive Species Compendium. Linum usitatissimum – datasheets.
• Muir, A. D., & Westcott, N. D. (2003). Flax: The Genus Linum. CRC Press.
• Diederichsen, A., et al. (2006). Flax genetic resources. In: Singh, R. J. (Ed.), Genetic Resources, Chromosome Engineering and Crop Improvement. CRC Press.
• Zohary, D., & Hopf, M. (2000). Domestication of Plants in the Old World. Oxford University Press.