Cassava is a perennial woody shrub with an edible root, which grows in tropical and subtropical areas of the world. Cassava originated from tropical America and was first introduced into Africa in the Congo basin by the Portuguese around 1558. Today, cassava supports the livelihood of over 300 million Africans.
It is rich in carbohydrates, calcium, vitamins B and C, and essential minerals. However, nutrient composition differs according to variety and age of the harvested crop, and soil conditions, climate, and other environmental factors during cultivation.
In sub-Saharan Africa (SSA) cassava is major staple crop grown for food and industry by small-scale farmers and a few mechanised medium to large scale farms. It thrives in good soil conditions and also grows even in poor soils where other staples would not survive and require comparably limited labor requirements. It provides food security during conflicts when the invader cannot easily destroy or remove the crop, since it conveniently grows underground. It is also a food security crop for the fact that it thrives in under harsh weather conditions, and a wide range of soil types with minimal management. Cassava is usually intercropped with vegetables, plantation crops (such as coconut, oil palm, and coffee), yam, sweet potato, melon, maize, rice, groundnut, or other legumes. The application of fertilizer remains limited among small-scale farmers due to the high cost and lack of availability. Roots can be harvested between 6 months and 3 years after planting.
Apart from food, cassava is very versatile, and its derivatives and starch are applicable in many types of products such as foods, confectionery, sweeteners, glues, plywood, textiles, paper, biodegradable products, monosodium glutamate, and drugs. Cassava chips and pellets are used in animal feed and alcohol production. The cassava peels are being transformed from waste to wealth as feed for poultry and other livestock
More than 291 million tons of cassava were produced worldwide in 2017, of which Africa accounted for over 60%. In 2017, Nigeria produced 59 million tons making it the world’s largest producer (approximately 20% of global production) with a 37% increase in the last decade. Nigeria exports about 3.2 million tons annually and earned a record $136 million in 2013.
Cassava production depends on a supply of clean certified quality stem cuttings. The multiplication rate of planting materials is very low compared to grain crops, which are propagated by true seeds. In addition, cassava stem cuttings are bulky and highly perishable as they dry up within a few days. However, there are rapid multiplication techniques like the two node cuttings, shoot tip multiplication , use of tissue culture plantlets and use ofSemi autotrophic hydroponics (SAH) to multiply seed for the growing seed system
Over 26 million hectares of cassava were planted worldwide in 2017, with about 76% in Africa. Cassava requires less labor than all other staple crops (21% in working days as compared to maize, yam and rice). However, it requires considerable postharvest labor because the roots are highly perishable and must be processed into a storable form soon after harvest. Roots can be harvested between six months and three years after planting. The in-ground storage ability of cassava makes farmers harvest in bits or as piece meal to take advantage of good market price and seasonal changes with demand and supply of fresh roots, and products
Many varieties have different levels of cyanogenic potential, that results in the production of cyanide when cells are broken for enzymatic reaction to occur. The level of cyanide can make products unsafe for consumption if inadequately processed. Various processing methods, such as grating, chopping, soaking, sun drying, and fermenting, toasting causes the gas to evaporate or become volatile hence levels are reduced to safe amounts.
Nearly every person in Africa eats around 80 kilograms of cassava per year. It is estimated that 37% of dietary energy comes from cassava. The Democratic Republic of Congo is the largest consumer of cassava in SSA where leaves and roots are consumed, followed by Nigeria, where almost 70% of the roots produced go into gari production, 15% into fufu, 10% into industrial use, and 5% for the fresh market.
Disease and constraints
The major pests of cassava in SSA are the cassava green mite and the variegated grasshopper. The main diseases affecting cassava are cassava mosaic disease (CMD), cassava bacterial blight, cassava anthracnose disease, and root rot. CMD alone accounted for an estimated 47% of East and Central Africa’s cassava production losses during a serious outbreak beginning in the early 1990s until 2006. Pests, disease and poor cultivation practices combined can cause yield losses as high as 50% in all of Africa.
IITA’s research and impact
IITA scientists have played a leading role in developing improved cassava varieties which are disease- and pest-resistant, low in cyanide content, drought-resistant, early maturing, and high yielding. Disease-resistant varieties give sustainable yields of about 50% more than local varieties. Distribution of CMD-resistant varieties in response to the CMD outbreak in East and Central Africa resulted in production levels recovering to pre-epidemic levels in less than five years. Improved cassava varieties are now used in most cassava-growing countries in SSA. IITA advanced genetic materials are used by many cassava breeding institutes in Africa, and many varieties have been released with a genetic back ground of IITA improved clones.
IITA’s biological control program resulted in a 95% reduction in cassava mealybug damage and a 50% reduction in damage caused by the cassava green mite.
Postharvest strategies include the development of effective and simple machines and tools that reduce processing time and labor, and production losses. With these machines, losses can be reduced by 50% and labor by 75%.
During the past three decades, IITA has trained more than 9000 researchers and technicians in ten African countries in processing and in new uses for high-quality cassava flour (HQCF). As a result, the private sector in Madagascar, Nigeria, Tanzania, and Uganda have begun using HQCF as a raw material for processing secondary products such as biscuits and noodles.
Cassava Weed Management
Project Name: Cassava Weed Management Project
Project Name: Building an Economically Sustainable Integrated Cassava Seed system
Project Name: TAAT Cassava Compact