Cassava, Manihot esculenta, is a perennial shrub in the family Euphorbiaceae grown primarily for its storage roots which are eaten as a vegetable. The cassava plant is a woody plant with erect stems and spirally arranged simple lobed leaves with petioles (leaf stems) up to 30 cm in length. The plant produces petal-less flowers on a raceme. The edible roots of the plant are usually cylindrical and tapered and are white, brown or reddish in color. Cassava plants can reach 4 m in height and is usually harvested 9-12 months after planting. Cassava may also be referred to as Brazilian arrowroot, manioc, yuca or tapioca and the origins of the plant are unknown.
The cassava plant is grown for its roots which are used as food. Cassava has the ability to grow on poor soils where other crops do not grow well. Cassava is also a suitable crop to grow when there is drought. Because cassava roots can be stored in the ground for up to 24 months, and some varieties for up to 36 months, harvest may be delayed until market, processing, or other conditions are favorable.
Plant Information
| Botanical Name | Manihot esculenta |
| Common Name | Cassava, Manioc, Yuca, Tapioca |
| Plant Type | Woody shrub, perennial |
| Mature Size | Up to 14 ft. tall, Up to 10 ft. wide |
| Sun Exposure | Full sun, partial shade |
| Soil Type | Sandy, loam, well-drained |
| Soil pH | Acid, neutral, alkaline |
| Bloom Time | Throughout the year |
| Flower Color | Whiteish |
| Hardiness Zones | 8-12 (USDA) |
| Origin | Probably Africa or South America |
| Toxicity | Some varieties are toxic to people and pets |
How To Plant, Care, Harvest And Store
Planting Cassava
Propagation from storage roots is impossible, as the roots have no buds. Cassava is propagated through cuttings. The most suitable cuttings are 20-30 cm long and 20-25 mm in diameter (with 5-8 nodes), preferably from the middle browned-skinned portion of the stems of plants 8-14 months old. Cuttings from older, more mature parts of the stem give better yield than cuttings from younger parts, and long cuttings give higher yields than short cuttings. Select cuttings from healthy plants. Cuttings slightly infested with pests can be treated by immersion in heated water (mixing equal volumes of boiling and cold water) for 5-10 minutes just before planting.
The interval between cutting stems and planting should be as short as possible (not more than a couple of days). Cassava cuttings may be planted vertically, at an angle, or horizontally. The drier the soil the bigger the part of the stem placed in the soil. Under very dry conditions, plant cuttings at an angle and cover the larger part with soil. Vertical planting is best in sandy soils, as the roots develop deeper in the soil. Horizontal planting leads to a large number of thin stems, which may cause lodging. Moreover, the roots develop more closely to the surface and are more likely to be exposed and attacked by rodents and birds. Do not plant cuttings upside down, as this drastically reduces yield.
The spacing between plants will depend on whether cassava is grown as a sole crop or with other crops (intercropping). If cassava is being grown alone, plants should be planted 1 meter apart from each other. This means that 10.000 cuttings are required for 1 ha (4000 cuttings per acre). If cassava is being grown as an intercrop, the branching habit of both the cassava and the other crops should be considered, making sure there is enough space for the plants.
The best land for planting cassava is flat or gently sloping land. Steep slopes are easily eroded. Valleys and depression areas that usually get waterlogged are not very suitable and cassava roots do not develop well. Before planting get to know the history of the land (previous crops, types of weeds, diseases and pests).
Soil preparation varies from practically zero under shifting cultivation to ploughing, harrowing and possible ridging in more intensive cropping systems. Planting on mounds and ridges is recommended, especially for areas with rainfall of more than 1200 mm per year or in areas where soils get waterlogged (e.g. valleys and depressions). Ridging may not give higher yield, but harvesting is easier and soil erosion may be reduced, especially by contoured ridges. In sandy soils, minimum tillage and planting cassava on the flat are appropriate. Plant at the beginning of the rainy season.
Also Read: How to grow and care for Giant Pumpkin
How To Care For Cassava (Yuca) Plant
Weeding is necessary every 3-4 weeks until 2-3 months after planting. Afterwards the canopy may cover the soil and weeding is less necessary. Although cassava grows rather well on poor soils, it requires large amount of nutrients to produce high yields. To maintain high yields, it is necessary to maintain the fertility of the soil. Phosphorous is important for root development. Symptoms of phosphorous deficiency are stunted growth and violet or purple discolouration of the leaves. In the absence of good compost, rock phosphate can be applied if needed. Potassium is also needed by cassava and can be applied in the form of compost or wood ashes. Potassium deficiency symptoms are: stunted growth, dark leaf colour which gradually becomes paler, dry brown spots on tips and margins of the leaves and “burnt” edges of leaves.
However, it is important to provide good growing conditions for the plants, as healthy plants are able to withstand some damage by pests and diseases. In general, cassava responds well to farmyard manure. Manure can be applied at land preparation to increase soil nutrients, to improve the soil structure, and to improve the ability of the soil to hold water. Mulching cassava, especially after planting, is helpful when growing cassava in dry areas or on slopes.
Harvesting
Harvesting is done either piece-meal or by uprooting whole plants. Young plants are usually harvested piece-meal, while old plants are more commonly uprooted to prevent the storage roots becoming very fibrous. As cassava roots do not keep fresh more than 2-3 days after harvesting, not all plants are harvested at once, but rather harvesting as the roots are consumed. When cassava is grown for urban markets they are harvested in bulk. Cassava is usually harvested 9-12 months after planting. It is sometimes harvested earlier if needed for food. Storage roots become too woody if harvesting is delayed. Early maturing varieties are ready for harvesting at 6 months while late maturing varieties are ready 12 months after planting.
Pests And Diseases
Pests
- Cassava mealybug
- Scale
- Aphids
- Spider mites
Diseases
- Cassava mosaic virus (ACMV)
- Cassava bacterial blight
- Cassava anthracnose
- Root rot
- Blight leaf spot
- Cassava frogskin
- Cassava brown streak virus disease (CBSD)
Other threats
- Birds
- Rodents
- Monkeys
- Pigs
- Domestic animals (cattle, goat and sheep)
Also Read: Varieties of Pumpkin
Varieties
There are two varieties of cassava—sweet and bitter. Both Cassava varieties contain prussic acid (hydrocyanic acid), which can cause cyanide poisoning; therefore, it is not advisable to eat large portions of raw cassava. The sweet variety of cassava has fewer of these compounds, and does not require as much processing. Bitter cassava is very similar in cultivation and general appearance to sweet cassava, but produces much higher quantities of cyanide compounds.
Storage
Cassava does not store well when fresh and therefore has to be peeled, chopped and dried in the sun. It can then be stored in the form of chips or flour under dry conditions.
Use
The cassava plant is used mainly for food for human consumption. It can also be used as animal food. In many homes cassava provides a source of food and supplies energy. It can be roasted, boiled or made into flour for porridge, Ugali, Fufu or garri Cassava leaves are also consumed as a green vegetable, which provides protein and vitamins A and B.
How To Get Rid of Poison from Cassava
The presence of cyanide in cassava constitutes a clear threat to health, unless these compounds are removed before the cassava is consumed. There are several methods of removing the cyanide from cassava. Simple drying reduces the level of cyanide, though this may not be adequate to make it safe for consumption. Soaking the roots in water first, to leach out cyanide, produces a safer starch. So does fermenting the roots, either whole, shredded or in pieces, before drying. Roasting the tubers, or boiling them in multiple changes of water, will also reduce the cyanide content to manageable levels.
Further References
- List of cassava diseases: https://en.m.wikipedia.org/wiki/List_of_cassava_diseases
- Global Cassava Developement Strategy: https://www.fao.org/agriculture/crops/thematic-sitemap/theme/hort-indust-crops/global-cassava-developement-strategy/en/
- Cassava farming Practices: https://environmentalevidencejournal.biomedcentral.com/articles/10.1186/s13750-018-0142-2
- Cassava Production In Nigeria: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7553005/
- Digital Tools For Smart Cassava Farmers: https://www.premiumtimesng.com/news/377925-six-digital-tools-for-smart-cassava-farmers-in-2020.html