Cassava

Manihot esculenta

1. Identification and origin

Cassava (Manihot esculenta Crantz), belonging to the Euphorbiaceae family, is a tropical crop native to South America, with its domestication centre in the Amazon region. It was one of the first plants domesticated by indigenous peoples, later spreading to Africa and Asia through colonial routes. Today, it is one of the main sources of carbohydrates for millions of people in tropical regions.

2. Economic importance

Cassava is grown mainly for the production of starch-rich roots, used in human food (flour, tapioca, starch), in animal feed and in industry (modified starches, bioplastics, ethanol). It is a strategic crop owing to its drought tolerance, ability to produce on poor soils and high resource-use efficiency. The largest producers include Nigeria, the Democratic Republic of the Congo, Thailand, Indonesia, Brazil and Ghana.

3. Botanical characterisation

A perennial shrubby plant, 1–4 m tall, with a woody stem and variable branching. The leaves are palmate, with 5–9 lobes, long petioles and colouring that ranges from green to purplish. The flowers are small, unisexual, grouped in terminal inflorescences. The tuberous roots are elongated, rich in starch and vary in colour (white, yellow). The root system is deep and adapted to dry soils. The plant has sweet and bitter varieties, the latter containing higher levels of cyanogenic glycosides.

4. Soil and climate requirements

Cassava adapts well to tropical and subtropical climates, with ideal temperatures between 25–30 °C. It tolerates prolonged periods of drought, but responds positively to rainfall between 1 000–1 500 mm per year. It prefers light, well-drained soils of sandy to sandy-loam texture, with a pH between 5.5 and 7.0. It is sensitive to waterlogging and compacted soils. The crop is often established from stem cuttings.

5. Main pests

• Whitefly (Bemisia tabaci): Honeydew, sooty mould and transmission of viral diseases.
• Cassava mealybug (Phenacoccus manihoti): Leaf curling, chlorosis and reduced growth.
• Mites (Tetranychus urticae, Mononychellus tanajoa): Leaf discolouration and loss of vigour.
• Root weevil (Cylas spp.): Boring and deterioration of the roots.
• Caterpillars (Noctuidae): Defoliation and damage to young shoots.
• Nematodes (Meloidogyne spp., Pratylenchus spp.): Root galls and decline in production.

6. Main diseases

• Cassava bacterial blight (Xanthomonas axonopodis pv. manihotis): Wilting, necrosis and plant death.
• Cassava mosaic (CMV, EACMV): Mosaics, deformations and a drastic reduction in production.
• Root rots (Phytophthora spp., Fusarium spp.): Wilting and rotting of the roots.
• Anthracnose (Colletotrichum gloeosporioides): Lesions on stems and petioles.
• Powdery mildew (Oidium spp.): White coating and reduced photosynthesis.

7. General crop management

Includes the selection of varieties adapted to the local climate and tolerant to diseases, the use of healthy cuttings, planting in well-drained soils, weed control in the early stages, crop rotation to reduce pressure from pests and nematodes, and monitoring of whitefly and cassava mealybug. Harvesting should be carried out between 8–18 months after planting, depending on the variety and the commercial destination.

Bibliographic references

• EPPO Global Database. Manihot esculenta – pests and diseases.
• CABI Invasive Species Compendium. Manihot esculenta – datasheets.
• Hillocks, R. J., Thresh, J. M., & Bellotti, A. C. (Eds.). (2002). Cassava: Biology, Production and Utilization. CABI.
• El‑Sharkawy, M. A. (2004). Cassava biology and physiology. Plant Molecular Biology.
• Howeler, R. (2014). Sustainable Cassava Production in Asia. CIAT.