The Cassava Program

Program Leader: Dr Luis Augusto Becerra López-Lavalle

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The World of Cassava

Cassava is the third most important food crop in the tropics, after rice and maize. The root crop is grown by millions of smallholders who rely mostly on low-technology farming systems and often in marginal areas with poor soils and low water availability. Cassava farmers are among the world’s poorest and most disadvantaged, but despite the challenges cassava remains one of the few crops offering both food and economic security to smallholder communities living in those environments. For many, it also signifies a path out of poverty.

Cassava cultivation is an entry point for employment and income generation for smallholder and landless farmers, and the impact of this activity extends to countless processors and traders over the world. Cassava's resilience and ability to remain a profitable crop in poor soils with unpredictable rainfall makes it an ideal crop to grow on marginal lands where cereals and other crops struggle to earn a living for farmers growing such crops. Cassava is a key crop for several tropical farming systems facing challenging conditions from climate change, although its expansion will be facing increasing pressure from pests and diseases. Generally, cassava production is a labor-intensive, subsistence-oriented undertaking, with low levels of technology uptake, high post-harvest losses, and weak linkages to markets, despite being a feedstock for numerous industrial applications, including as a source of food, feed, and starch. Farmers aiming at high productivity must also take some risks, including increased costs for fertilizer and pest control.

The fact that Latin America is the center of origin of cassava explains CIAT's move to create its Global Cassava Program in the early 1970s, while prioritizing cassava research that could not only serve the region but also provide strategic germplasm to IITA for Africa, as a major consumer of cassava as food by the poorer rural populations. Similarly, CIAT drove the development of cassava as an industrial crop in Southeast Asia, setting up an office for that purpose in Thailand. This successful model is now being extended to other countries in the region, where high demographic pressure requires high-impact crop improvements. After nearly 50 years since its inception, the program continues to deliver on its initial objectives and has embraced the challenges outlined in the United Nations’ Sustainable Development Goals. The Global Cassava Program is now part of the Alliance of Bioversity International and CIAT and the One CGIAR. The Alliance recognizes the role cassava plays in generating income for farmers and comunities where poverty is widespread.

The Global Cassava Program operates as an effective multidisciplinary team across six strategic Research and Service Areas (RSAs), which are strategically aligned to best respond to the demands of our main stakeholders: the CGIAR Research Program for Roots, Tubers and Bananas (CRP-RTB), USAID, BMGF, HarvestPlus, ACIAR, as well as various NARS and private organizations (i.e., Ingredion and TTDI). The six RSAs are invested in developing better cassava varieties, facilitating access to clean planting materials, monitoring and surveillance of pests and diseases, improved farming and postharvest practices, and the development of sustainable cassava value chains to unlock new cassava market growth.

Why cassava?

Cassava has been a traditional crop of Latin America for almost 10,000 years, with its center of origin located on the south-western border of the Amazon basin. From here it spread to become one of the most important calorie source staples in the least-developed and low-income, food-deficit countries in the tropics. This is due to cassava’s resilience, which allows it to grow on low-fertility soils and under harsher drought and heat-stress conditions than other staples, while remaining an economically viable cash crop.

Cassava varieties are propagated via stem cuttings, which means farmers can produce and trade their own planting material. Cassava roots make up for their post-harvest perishability by being able to remain in the ground and harvested over several months as needed, providing additional management flexibility and compatibility with diverse farming systems. Also, cassava is widely transformed into a range of traditionally processed, storable product. These attributes explain why cassava has become such a success story in the tropics. At the same time, these same attributes and their association with marginal lands have contributed to cassava becoming a misunderstood crop by some people working in human development organizations.

Although commonly considered a calorie source, cassava is also becoming a source of the vital micronutrient beta-carotene, or provitamin A. The Cassava Program has identified germplasm rich in this essential micronutrient and made lines carrying this nutritional attribute an essential component of its breeding program, thereby contributing to the United Nations’ Sustainable Development Goal 3, Good Health and Well-being, by improving the health status of cassava consumers, especially children.

Cassava consumption is quite diversified, with the root being eaten fresh or processed in many traditional ways for storability. They are also pelletized for animal feed or processed into ethanol, and dry starch can be used as industrial feedstock, while the leaves can be used for human consumption and animal forage.

End-uses of cassava are being further diversified in ways that may require more specialized varieties to meet specific requirements. Due to its desirable physicochemical properties, cassava starch finds its way into many daily-life products such as food flavorings or thickeners in the paper and textile industries.

Sustaining the tropics

Since the turn of the millennium, world annual cassava production, currently at about 270 million metric tons, has been increasing at an annual growth rate of about three per cent, although this growth has been mainly driven by increases in planting area. Cassava is predominantly grown for its starchy roots, but leaves are also consumed as protein-rich food and feed for livestock. In Africa and Latin America, most cassava is grown as a food crop, while in Southeast Asia it is primarily processed into starch for the food and beverage industries and various other industrial applications.

Due to its industrial utility, cassava is also an important and highly competitive, climate-change-ready cash crop, thus contributing to the basic sustenance of smallholders and landless farmers. Dry cassava roots contain more than 80 per cent starch, which is processed at different scales, from artisanal to highly technical processing plants, which creates employment for numerous traders and processors worldwide.

Even though cassava starch represents only eight per cent of global starch production, it is the most traded starch in the world. In Southeast Asia, cassava has evolved to become a major industrial crop, feeding a US$4 billion trade in chips, pellets and raw starch, with markets in China and other growing Asian economies as the main buyers.

Cassava production in Southeast Asia has gone through a steep growth phase and is now moving into a period of market consolidation. With ongoing challenges like climate change, pest incursions via informal seed systems, and declining yields this is a critical period during which One CGIAR needs to focus on providing support to this young cassava industry and particularly to the eight million farmers who depend on this crop, many of them belonging to poor ethnic minorities.

Regionality

Agronomic performance of varieties is typically region-specific and requires tailored solutions. Factors limiting productivity are diverse and go beyond common agronomic challenges; they include availability and access to essential resources such as good soils, water and fertilizer, experience with sustainable practices, and farming system integration.

Latin America and the Caribbean

Cassava originated in the southern Amazon basin before spreading across the tropical regions of the Americas during the process of domestication, thousands of years ago. Hundreds of regionally different landraces, along with a wide range of processing methods and consumption patterns, bear witness to a long tradition of cassava growing in the tropical Americas.

Brazil and Paraguay are the main producers of cassava in Latin America, with production shared by small and large farmers. Some regions in Brazil and Paraguay have experienced a gradual increase in industrial uses for cassava starch, with processing plants being established and supply chains developed.

For many years, the CGIAR Cassava Program has been working on increasing industrial cassava production in Colombia. Their work includes technological improvements, reducing energy and water consumption, and the creation of market value chains for cassava derived products. Success for these efforts depends on market accessibility and capital assistance, which is where the strengths of the program lie, thanks to its established national and international research, development and extension networks.

Despite its long history of cultivation in Andean countries, cassava yields in this region are in decline. As cassava remains a key crop for sustenance due to its resilience and adaptability, farmer needs in the region are being addressed by targeted varietal diversification as well as improved processing technology. Novel, attractive industrial applications and increased urban consumption are needed to make cassava a profitable crop with the potential to improve the livelihoods of many smallholders.

Efforts towards achieving this goal are exemplified by work being carried out by the Cassava Program to improve the productivity of small industrial starch-processing plants in Colombia and to transition cassava starch into mainstream starch markets, with due consideration to changing eating habits of a more urbanized population.

Sour starch is an important local product in parts of Colombia, used to prepare a traditional bread called pan de bono. The Cassava Program has helped improve the starch extraction process and the use of defined microbial starter cultures to raise the overall efficiency of the process. Sour starch production is an example of a small, artisanal rural industry with potential for improvement and integration into the urban value chain.

Southeast Asia

Countries in the region account for about a quarter of global cassava production, contributing to the livelihood of more than eight million smallholder farmers.

Cassava’s adaptability makes it a potential gateway crop to long- term environmentally and economically sustainable farming systems by allowing farmers to bring exhausted and degraded land back into production, ideally as a bridge to more valuable crops.

While mainly consumed as a staple in Africa, Latin America, Indonesia and the Pacific, industrial applications predominate in mainland Southeast Asia, contributing to rural livelihoods and national economies.

Thanks to its wide adaptability and resilience to various stresses, cassava is a climate-ready crop and expected to perform better than many other tropical crops. The role of cassava in food security and income stabilization for the world’s poorest is expected to become increasingly critical in a changing world climate.

Cassava starch quality and pricing makes it competitive against other starches, but productivity must keep improving to retain this market position.

In Southeast Asia, farmers obtain about eight metric tons of dry matter per hectare from roots, of which more than 80 per cent is starch. Over time, the Cassava Program’s contribution has led to doubling of yields and a 20 per cent increase in dry matter, further contributing towards Sustainable Development Goals related to poverty alleviation.

Informal seed systems operating across international borders create a major challenge to sustainable production in Southeast Asia by exacerbating the spread of diseases that have entered the region in recent years and which are already causing some significant losses. The Cassava Program is working with major players in the region to harness the power of existing informal seed systems while addressing phytosanitary and quality issues.

Africa

Since the introduction of this New World crop hundreds of years ago, cassava has become a traditional and widely grown food energy source for more than half a billion people in sub-Saharan Africa, with Nigeria and Ghana responsible for about half of the continent’s production, which totals greater than 60 per cent of world’s cassava production. Production has steadily increased over the years through expanded planting area rather than productivity improvements, especially in the more arid regions. About 90 per cent of production is in the hands of smallholder farmers and mostly as part of mixed-cropping farming systems in which cassava constitutes an essential sustenance element due to its higher resilience to infertile soils and water-stressed environments.

Cassava is generally consumed fresh or processed domestically by sun-drying, grating, soaking in water or fermentation to remove the cyanide liberated from glucosinolates present in all parts of the plant and make the derived products storable and acceptable for human consumption. Most cassava in Africa is consumed locally, with delivery into domestic markets ranging anywhere between 20 and 70 per cent, depending on market integration of farms.

Nigeria, the major cassava producer in the world, has shown initiative by partially substituting wheat flour with cassava flour in bakery products, thereby saving the country foreign exchange and increasing the income of cassava processors and farmers. Because of the perishability of cassava roots, such initiatives depend on improved access for producers to the transport and energy grid before production can be diversified into industrial uses such as starch, animal feed, ethanol and flour. Flour processors are also affected by competition with gari processors, as the latter can afford to pay higher prices for cassava starch due to their larger profit margins.

Over time, the Cassava Program has distributed thousands of cassava accessions and varieties in Africa (see also germplasm section) and contributed to major biological control campaigns to manage pests like the cassava hornworm using baculoviruses or parasitic worms to combat cassava mealybug, with the latter alone having saved the continent about US$20bn in potential losses. These days, the program is part of an international program to combat whitefly, contributing to the molecular characterization resistance sources for breeding purposes.

Program Strengths

• Direct access to the global cassava germplasm collection held by the Alliance of Bioversity International and CIAT.
• Highly qualified scientists in-country, embedded into cultures and landscapes.
• Diverse and robust partnerships in target countries with access to regional and local technology distribution pathways.
• Established relationships with a range of donor agencies, creating funding priority pluralism and empowering a holistic response.
• Program structure delivering an integrated technical, cultural and socioeconomic approach.
• Cross-disciplinary teams feeding the varietal breeding-to-deployment pipeline and capable of working across whole-farm systems.
• A team of passionate researchers seeking innovative and context-appropriate solutions.
• Established institutional and government relationships, with capacity building in target countries.
• Long history of crop-specific R&D and quantifiable, global impacts.

Ongoing challenges the cassava program is addressing

• Ongoing threat of pests and diseases placing pressure on varietal resistance.
• Informal seed systems acting as disease vectors across country boundaries.
• Growing yield gap menacing many smallholder livelihoods.
• Technology adoption pathways depend on local intermediaries often lacking resources.
• Dependence on national policies and crop-specific support to implement on-ground change.
• Negative perceptions of cassava as contributing to deforestation and erosion in Southeast Asia.

Doing what we do best

Since its inception, the Cassava Program has excelled in germplasm deployment and development based on the identification of regional needs, be it climatic adaptation, consumer needs and management of biotic stresses. More than 43,000 accessions, including about 6500 varieties, have been handed to 84 countries worldwide. The program has also released 35 improved varieties in LAC and 25 in SEA. Worldwide, 48 varieties related to CGIAR material cover 40 per cent of the cassava growing area. A multibillion-dollar investment by CGIAR and partners over time has resulted in a benefit-to-cost ratio of 2.28 globally or 5.27 for SEA alone.

The Cassava Program focuses on delivering novel cassava varieties based on product profiles defined by regional needs (see graph). Pest incursions pose one of the worst challenges to progress made to date. They are moving targets that require continual attention if gains to date are to be maintained and further improved.

Whiteflies, for example, are carriers of several viral plant diseases, among them cassava mosaic disease (CMD), which causes annual losses of about US$1 billion in eastern and central Africa alone. It also affects countries in SEA. Another whitefly-transmitted virus causes cassava brown streak disease (CBSD), resulting in losses of more than US$700 million annually in Africa. The mycoplasma caused witches’ broom disease affects several countries in Southeast Asia while frogskin disease causes important losses in Latin America and the Caribbean.

Disease incursions previously unknown to growers have reinvigorated the role of the CGIAR and their partners in developing and delivering disease-resistant, locally adapted varieties. The Cassava Program is also one of 16 international partners in the Bill and Melinda Gates Foundation-funded Cassava Whitefly Project and is working on the molecular characterization of genetic sources of resistance.

Strategic product profiles being delivered to national programs traits

• Nutrition and sustenance: High provitamin A; delayed postharvest physiological deterioration; low glycemic index
• Industrial uses: High and stable dry matter; waxy starch; small-granule starch
• Agronomy: Herbicide resistance; tolerance to high-density planting
• Quality and functionality: Cooking quality and texture
• Disease resistance: CMD, CBSD, whitefly, witches’ broom, and frogskin disease
• Physiology: Drought and heat tolerance; early maturity; vigorous growth
• Breeding: Hybrid breeding to boost yield

Outcomes

• Diversifying cassava genetics targeted to specific agroecologies and uses
• Reduced yield gaps in diverse farming systems
• Smarter, cost-effective solutions across the breeding and value chains
• Variety-specific agronomic packages, including more efficient pest and disease management
• More sustainable resource utilization
• Targeted research and interventions for efficacious technology adoption
• Improved soil health on degraded lands