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Cassava is an important root crop and is a source of dietary energy to over 700 million people in the tropical and subtropical Africa (Prochnik et al., 2012). Cassava is the fourth most important source of calories in the developing world after wheat, maize, and rice. More than 40% of Africa's population consume cassava as a staple food, and it is the second most important crop after maize (FAOSTAT, 2019). The roots and leaves are the two most valuable parts of the mature cassava plant that can be used as a food source (Morgan and Choct, 2016). Cassava is grown primarily for its enlarged storage roots, which are consumed as food for humans in various forms (Chandrasekara and Kumar, 2016). Cassava roots are rich in carbohydrates and are a good source of energy, a moderate source of minerals and vitamins, and a poor source of proteins (Montagnac et al., 2009). In particular, cassava is a good source of Vitamin C, thiamine, riboflavin, and niacin (Montagnac et al., 2009). Cassava has the potential to produce and store more carbohydrate per unit area under production than any other major grain and root crops (El-Sharkawy and De Tafur, 2010). Cassava roots can be converted into many food products, such as chips, pellets, pasta, flour and starch, with good storability and relatively low postharvest losses (Adelekan, 2010). The nutritious leaves can also be harvested for human consumption as a green vegetable (Montagnac et al., 2009) and for animal feed (Lukuyu et al., 2014). The leaves are rich in iron, calcium, vitamins, and a good source of proteins (Montagnac et al., 2009).

Cassava storage roots can be stored in the ground for up to 2 years after maturity, and can be harvested at any time of the year when a farmer needs food (Sanchez et al., 2013). The natural high storability of cassava compared to other root crops provide farmers the opportunity to capitalize on the best market opportunities (Hershey et al., 2012). Farmers can plant and harvest cassava without any capital input on marginal lands where other crops cannot be produced. Cassava is grown predominantly by small-scale farmers with limited resources on marginally fertile soils (Kintché et al., 2017). The low input land use systems (also commonly referred as small-scale agriculture), which they operate on a sustainable basis is of great benefit to resource poor farmers and to the eco-system (Altieri et al., 2012). Consequently, cassava is considered as an excellent food security crop and a household food bank that can be drawn anytime when adverse climatic conditions limit the production of other crops (Nakabonge et al., 2018).

However, high cyanide content, poor protein, and micronutrient content, and pest and disease issues are the major problems in using cassava as a food crop. Serious malnutrition problems have been reported in countries that rely primarily on cassava food products, with little or no protein supplements (Akinola et al., 2020). Micronutrient deficiencies present in some staple food crops have been improved via bio-fortification (Bouis and Saltzman, 2017). Cassava has been targeted for bio-fortification because of its unique geographical distribution (Talsma et al., 2016). There is considerable potential for enhancing the nutritional value of cassava through breeding. Variation in cassava for carotene content (Ceballos et al., 2017), protein content (Carvalho et al., 2019), and micronutrient content (Burns et al., 2012) have been reported in the available cassava germplasm collections.

Although South Africa is often characterized by food self-sufficiency at national level, about 20% of the households' experience food insecurity, malnutrition, unemployment and poverty (Abdu-Raheem and Worth, 2011). The fact that cassava's ability to grow and provide reasonable yield in areas where environmental conditions and per capita resource levels are declining makes it an ideal candidate to be a food security crop. In addition, most South Africans have a relatively monotonous dietary system, mainly based on maize and bread starch, and protein such as chicken and milk. Diversification of the crop base that require low agricultural input such as cassava will improve food and nutrient security at a rural household level. Hence, cassava can stabilize food security by providing food for many households and serving as a cash crop as a source of industrial starch in South Africa. In South Africa, the role of cassava as food security crop needs to be viewed from dual perspectives; first through its direct contribution to household food security and second indirectly by being cash crop through raw material sold to the starch industry. Hence, discussing the industrial application is unavoidable while elaborating the role of the crop on food security.

Global climate change and its impacts have been observed and reported (Miller, 2008). Changes in precipitation amount and patterns, temperature, atmospheric carbon dioxide level and water availability are indicators of climate change (World Bank, 2008). The global mean temperature has increased by ~0.74°C over the last century (Miller, 2008) and 1.1°C by 2020. In some locations, an increase in the number of extreme hot days and a decrease in the number of extreme cold days have been observed (Singh and Singh, 2012). Likewise, changes in the intensity and patterns of precipitation have been witnessed as the Mediterranean region, southern Africa, and southern Asia had a decline in precipitation, whereas northern Europe, northern and central Asia, and the eastern portions of North and South America had an increase in precipitation (IPCC, 2007). These affect the length of crop growing period, development and yield (Cai et al., 2009). The climate change impacts on agriculture are unavoidable, hence implementing climate adaptation strategies are crucial to mitigate the negative impacts of climate change.

South Africa is a water scarce country where only 12% of its land are suitable for crop production (Donnenfeld et al., 2018). Most of South Africa's land surface (69%) is suitable for grazing and livestock farming. South Africa uses about 60% of its scarce water resources on irrigation to grow crops such as maize, potato, wheat, sugar cane, and sunflower (Baleta and Pegram, 2014). Climate change poses a significant risk to South Africa's water resources, food security, health, infrastructure, ecosystem functions, and biodiversity (Ziervogel et al., 2014). In South Africa, climate change projections have suggested that by 2050 mean national temperatures will increase by 5–8°C, with much reduced rainfall in the west and south of the country, and an increased risk of heavy rainfall events in the eastern parts of the country (Calzadilla et al., 2014). These will result in changes in rainfall patterns, evaporation rates, temperature ranges, reduced crop yields, and the emergence novel pests and diseases of crops and livestock (Calzadilla et al., 2014).

In addition to climate change, a decline in land quality due to soil degradation, soil acidification and land competition has dramatically increased the challenge of achieving national food security. Expanding the area of available arable land is not possible due to demographic pressure, urbanization and expansion of industries (Naab et al., 2013). Agricultural intensification has often been considered as the primary approach to meet the rising food demand. Enormous gains in agricultural production have been achieved due to agricultural intensification through rigorous utilization of fertilizers, pesticides, and irrigation (Mateo-Sagasta et al., 2017). The widespread application of synthetic fertilizers has generated varying degrees of soil acidification, groundwater contamination, and ecological degradation of the available arable land (Khan et al., 2018). Similarly, the worldwide chronic illness such as reproductive and birth defects, neurotoxicity, kidney and liver damage, high prevalence of cancer, and the emergence of more virulent strains of diseases and pests are related to excessive use of synthetic agrochemicals (Mossa et al., 2018). In South Africa, the commercial sector relies heavily on the use of irrigation, fuel, synthetic fertilizers, pesticides, and herbicides. Moreover, relatively few crops have occupied the major production areas and grown repeatedly year after year.

Climate change coupled with ecological degradation and water scarcity has curtailed food productivity, availability, accessibility, and quality at the national level. The above factors also aggravate the emergence of novel pests and diseases (Jones and Barbetti, 2012). The contemporary arrival of the fall army worm, which has destroyed maize, wheat and potato crops across Africa and Asia, is one of the negative impacts of climate change observed in South Africa (Amusan and Olawuyi, 2018). To ensure that the agricultural sector continues to play an important role in the economy, sustainable agro-ecological solutions should be implemented (Wezel et al., 2018). The implementation of eco-system-friendly, sustainable agricultural practices such as crop rotation and sequencing, integrated pest management, efficient water management, crop and varietal diversification and the use of well-adapted improved varieties are obligatory. Cassava is drought resistant and resilient to climatic changes, high temperatures, and poor soils, which makes it an important crop for the twenty-first century (Mupakati and Tanyanyiwa, 2017).

More than 90% of South Africa's primary energy is derived from fossil fuels that constitute 80% of the country's greenhouse gas (GHG) emissions (STATS-SA, 2018). About 77% of South Africa's energy needs are directly derived from coal, and 92% of coal consumption on the African continent is produced in South Africa (Baker, 2017). The heavy dependence on coal in South Africa is not only because coal is a relatively cheap source of energy, but also because South Africa has abundant reserves (STATS-SA, 2017). Fossil-based transportation fuels have been recognized as the largest contributor toward GHG emissions (Perera, 2018). Many countries ratified the Paris Agreement to reduce annual global greenhouse gas (GHG) emissions to between 30 and 50% by 2030 to prevent a global temperature rise (Shepherd and Knox, 2016). South Africa has also endorsed the Paris Agreement, and committed to reduce the contribution of coal-generated power from 82% in 2016 to 31% in 2050, as outlined in the Integrated Resource Plan (IRP) of 2016. Further, much of the national budget is spent on fossil fuel; hence, there is a growing commitment to explore alternative energy sources such as the use of renewable energy and the conversion of biomass to bioenergy (Petrie, 2014). The increase in the price of fossil fuel, coupled with the need to reduce greenhouse gases emissions, have driven the search for renewable sources of fuels.

Bioethanol production requires a highly productive, sustainable supply of feedstock, and appropriate processing technology. Cassava, apart from its traditional role as a food crop, is recognized as a potential feedstock crop for the production of bioethanol (Marx, 2019). Cassava is an excellent feedstock for ethanol production: it is adapted to a wide range of growing conditions, especially to marginal environments; it can be planted and harvested all year round; and cassava can be stored as dried chips before processing (Nguyen, 2007). Bioethanol can be produced from cassava either from storage roots or the cassava waste stream. Cassava storage roots, on average contain about 35% dry matter content, with a starch content of between 70 and 85% (Benvenga et al., 2016). Wang (2002), in his studies of bioethanol production potential of six energy crops, reported that the annual yield of bioethanol from cassava is significantly higher than from other crops (Table 1). Yang et al. (2017) achieved an ethanol yield of 0.9 g ethanol/L/h through a combination of aerobic and anaerobic fermentation processes, while Wang et al. (2017) reported an ethanol yield of 11.43% (v/v). Marx and Nquma (2013) achieved a final ethanol yield of 530 L of ethanol per ton of unpeeled cassava roots, which translated into 2,400 L/ha.

Cassava wastes are also a potential source of bioethanol and organic fertilizer (Ekop et al., 2019). Cassava waste includes leaves, stems, pulp, fiber peels and sub-standard tubers that can be used as ethanol feedstock. The peels and stems comprise of 28% of the total dry matter and can generate more than 60% ethanol, indicating the potential use of cassava wastes for ethanol production (Nuwamanya et al., 2012). Elemike et al. (2015) also reported that, depending on the starch-to-ethanol process, cassava wastes can have a starch content as high as 60% (w/w).

Cassava is the fourth most important source of plant-based starch in the world after wheat, maize, and potato (Sharma et al., 2016). The global demand for cassava starch is projected to be over 10 million tons by 2024 (Business wire, 2019). Technological advancements in the starch industry makes cassava an attractive source of modified starch such as food grade starch, and adhesive, paper, and textile grade starches (Adelekan, 2010). Cassava is thus considered to be a highly valuable industrial crop for the world today and in the future.

In South Africa, maize is currently the main crop used for food (37.4%), feed (39.8%), exports (17.9%), and industrial purposes (4.8%). It constitutes two-third of the commercial area planted in field crops, with an average annual production of ~10–12 million tons (Greyling and Pardey, 2019). Maize is the source of about 95% of the local starch produced in South Africa. Competition between industries utilizing maize products has resulted in the failure of the local starch industries to meet the starch demand of the country. Hence, South Africa imports around 66,000 tons of starch products annually, of which more than 33% is cassava (tapioca) starch (UN Comtrade, 2019). Although South Africa's starch import volumes experienced positive and negative growth patterns during the period 2008–2017, cassava starch import volumes have consistently been higher than those of maize, wheat and potato (Figure 2). If cassava can be used as an alternative starch source to satisfy the domestic starch demands, this will reduce competition among staple food commodities and reduce the volumes of imported starch.

Cassava storage roots contain a starch content that is about 40% higher than rice and 25% more than maize (Tonukari, 2004). Cassava starch is the cheapest and preferred known form of industrial starch, including in South Africa (Figure 2). The estimated demand for cassava starch alone in 2004 was 20,000 tons per annum; this demand would require more than 300,000 tons of cassava for milling and about 26,000 hectares of land under cassava production. Grasping the industrial potential of cassava in the starch industries and setting up rural cassava producers will create sustainable income sources and improve the livelihoods of rural community. Cassava starch also fetches a higher price on the market than maize, potato, and wheat starch. South Africa spends more than R40 million annually to import various starches, of which 17% is for cassava starch (UN Comtrade, 2019). The country imports most of the cassava starch from Asia and a small portion from the USA (IDC, 2017). Producing industrial starch from cassava locally will satisfy local starch demands, avoid competition among staple food commodities, relieve the country's economy from foreign currency strains, and reduce import volumes.

The largest exporters of cassava are not necessarily the largest producers. Although Africa is the leading cassava producer globally, most of the cassava crop is consumed domestically and considered as a non-trade commodity. Nigeria, the DRC, Brazil and Indonesia are the top producers of cassava globally. Despite attempts to promote cassava as a commercial crop in Africa, low international prices for maize starch has made cassava starch production in Africa unattractive. Asia is driving the world trade in cassava starch, with Thailand at the top of the ladder, followed by Vietnam, Germany, and China (Table 2). At the beginning, European countries were the only cassava importers. However, imports of cassava products by non-European countries expanded in the mid-1980's mainly because other markets were developed in Asia (Otekunrin and Sawicka, 2019). Presently, China, USA, France, and Germany are the top cassava importers (Table 3). Two-sample t-test analysis was made to compare the differences between the changes estimated over the categorical times. There was a significant change (p = 0.05) in export volume between the period 2010–15 and 2015–17. South Africa sources its cassava supplies mainly from South East Asia. However, with appropriate investment, planning and policy support, this situation could be reversed.

Agriculture in South Africa has a dual character (Gwebu and Matthews, 2018), which comprises of relatively few well-developed commercial farms and a large number of small scale, subsistence farms. The commercial sector is mainly based on capital intensive, export oriented and large-scale production. They produce about 90% of the total agricultural production and their farms cover about 86% of the country's cropland. Subsistence farming, on the other hand, relies on traditional production methods and is labor intensive, employing about 86% of the total farm labor (Pienaar and Traub, 2015). Small-scale farmers mainly produce for household subsistence. Cassava provides an opportunity to improve smallholder farmers' income and food security by unlocking economic value, by opening up marginal lands for cultivation and pooling communal resources in addition to commercial operation by organized farmers groups to enable mechanization.

Cassava is a labor-intensive crop that requires lots of labor from planting to processing. Hence, it can provide employment opportunities to unskilled labor in rural areas. Moreover, cassava is a bulky and highly perishable crop that needs to be processed before it is transported, which opens up opportunities for small-scale farmers to be involved in producing semi-processed materials and simple value-added products, for greater economic gains derived from marginalized or nutrient poor land. Developing the cassava industry in South Africa could play a role in transforming smallholder sector into small- and medium- sized enterprises by engaging them in distributing better quality planting materials, implementing intensive cassava production and establishing community-based primary processing systems. Establishment of small-scale farmer development programs will ensure sustainable productivity and profitability of cassava production for small scale and emerging farmers. These initiatives could be used to drive the economic empowerment of small scale and emerging farmers through meaningful integration with the secondary processing industries. This will be achieved through partnerships that create an enabling environment by closing all gaps in the value chain. The source of the innovative technologies for technology diffusion and deployment will be the developmental funding institutions as well as research councils.

The role of private and public sector needs to be well-defined and this will facilitate commercialization of crop technologies from public sector research. The ARC initiated a process to coordinate the cassava R&D in South Africa in light of the growing importance of the crop, and the lack of coordination among the various stakeholders. Several stakeholder engagements have been made, aimed at mapping the way forward for cassava R&D and commercialization of the crop in South Africa. During the various stakeholder meetings, aspects such as the opportunity and challenges of cassava research, available resources in terms of manpower and research funds, promotion and adoption of the crop and policy issues that need to be addressed were raised and discussed. The stakeholder forum discussed the need for an integrated approach with strategic partnership between the public and private sectors. This can be realized through close linkage between producers, starch-processing industries, farmer support programs, financial institutions and agricultural research institutions along the cassava value chain. Similarly, collaboration among governmental organizations would aim to share resources and to make an enhanced impact on food and nutrition security, and to increase production, productivity, profitability, and environmental stability, and to stimulate job creation.

The ARC was given the assignment to assess the current research capacity for supplying high-quality planting material and farmer-based small-scale production of cassava tubers for commercialization of the crop. The ARC was also tasked to drive the policy initiative to develop an evidence-based policy that will facilitate the equitable economic exploitation of the crop. The Technology Innovation Agency (TIA) agreed to explore the industrial potential of the crop and to assess the availability of financial resources to support essential cassava research programmes. It is envisaged that these initiatives will produce the required result in developing a viable starch industry underpinned by sustainable primary production supported by strong R&D. Previous studies had been undertaken with the objective of establishing cassava as a source of industrial starch, most of which failed. The TIA- led initiative was constructed to mitigate the shortfalls of these prior studies, namely to access diverse, disease-free cassava material germplasm; to screen the germplasm in multiple geographic regions over multiple seasons and using the data from these cultivar assessments to determine the feasibility of adopting suitable cultivars by small scale or emerging farmers in a pooled communal set-up. The study will provide the starting point for a local breeding program to develop superior cassava cultivars for South Africa.

Globally, cassava is recognized as an important food and industrial crop. The International Institute of Tropical Agriculture (IITA), International Center for Tropical Agriculture (CIAT), National Agricultural Research Institutes (NARs), and Universities in Africa have played leading roles in cassava improvement. The production, characterization and product development from cassava is at its infancy in South Africa compared to other African countries. It is vital that South Africa taps into the skills and advanced R&D programs of these institutions by establishing strong collaborative links. Capacity building can be done through fellowships, grants schemes, exchange and partnership programmes. Collaborative research in terms of information access, germplasm exchange and genotyping of elite germplasm should be imperative. In addition, to enhance the local knowledge base of cassava, formal training through postgraduate studies and informal trainings such as awareness creation among stakeholders and field days would be important.

The UN Conference on Trade and Development released a Policy Brief in 2010 suggesting that: “In the Twenty-first century, transforming the existing industrial-agricultural systems into knowledge- and labor-intensive rather than agro-chemical and energy-input-intensive is necessary” (Trade Development Report, 2010). The transformation should consider integration of local knowledge with modern agricultural techniques, giving strong emphasis to the available biodiversity and resources. A Trade Information Brief (TIB) for the Southern Africa Development Community (SADC) (2015) proposed cassava as a potential industrial crop for SADC's farmers. Although cassava has not been a traditional commodity in South Africa, exploiting cassava's potential for food, industrial starch and renewable energy will improve the livelihood of many farmers at a household level. Training is an integral part of any development activity and a process by which acquiring new knowledge, skills, practices, and attitude in the context of preparing farmers for improving agricultural productivity (Pandey et al., 2015). Training plays a key role in human capacity development, to equip farmers with skills, knowledge and competencies for sustainable crop production, resource utilization, and income generation (Yaseen et al., 2015). Therefore, adequate training on cassava production, processing and marketing is essential for farmers to acquire the necessary knowledge and skills to exploit the full economic potential of the crop. Accredited training modules in cassava production and processing, as well as financial and business management, will be developed. Production enterprises will have to be established and supported to enable farmers to produce and partially process products for the starch processing market.

The local production of the staple commodities such as maize, wheat and potato is affected by recurrent and severe droughts. Exploring alternative climate resilient solutions have become a priority. Awareness creation of the prevailing environmental conditions and the available mitigation strategies are imperative. As part of awareness creation, organization of symposia, conferences and workshops, at which researchers from local and international institutes can present their research findings on cassava should have a significant impact. These conferences can serve as essential forums to inform key policy makers, farmers, growers and processors to access first-hand information from experts in countries where cassava is a major crop. Funds should be accessed from national and international institutions. Furthermore, the use of a promotional hub is vital to introduce various cassava products to researchers, policy makers, producers, and processors to appreciate the economic importance of the crop.

The social enterprise model is a corporate model that addresses the social, environmental and economic aspects of any commodity development. In this model, the farmers are organized in a way that they play a key role in leading the primary production aspect, but are also stakeholders of downstream processing. The primary objective of the social enterprise model is to make farmers involved beneficiaries across the entire value chain. It is critical to develop the whole value chain in such a way it sustains itself and empowers farmers. One of the merits of this model is that it is socially viable as the majority of the society around the production area benefits from an environmentally sustainable production system. Second, cassava, being a multi-purpose crop, has production, processing and marketing components that provide job opportunity to the smallholder farmers across all the value chain. However, there is no example of feasible and successful agricultural social enterprise in South Africa that can be used as a model. However, it has been used successfully in other sectors such as education and training, according to a study done by the Gordon Institute of Business Sciences at the University of Pretoria (GIBS, 2018).

A commodity-based organization represents the entire value chain such as growers, consumers, processors, traders, importers, exporters, input distributers, and transporters. These types of organizations can play important role in promoting the particular interests of their members and advocating policy and regulatory changes. The South Africa cassava industry association (CIASA) was established under the Department of Trade, Industry and Competition (DTIC) to address and coordinate all aspects of the cassava value chain (IDC, 2017). Presently, even though CIASA attempts to be proactive, it was not be able to coordinate cassava research or the development of a cassava value chain in South Africa. The association was probably established too soon, when there was a lack of critical mass and political support. CIASA should be revived and strengthened to represent the cassava value chain in SA and the full spectrum of stakeholders. It was suggested, during a workshop with R&D stakeholders, that the constitution of CIASA should be revisited and its role should be redefined to support the cassava industry in SA as a whole, including researchers, which were not considered by the DTIC. DTIC included cassava starch in the 2016/2017 Industrial Policy action plan (IPAP) to promote trade activities in the industrialization of cassava, which was informed by the consultations leading to the establishment of CAISA.

Although the current demand for food cassava is small in South Africa, there is the potential to develop cassava products that are affordable and attractive to consumers in South Africa. Brazil has developed a wide range of cassava food products, and benefits from a strong domestic market (Demiate and Kotovicz, 2011). High-quality cassava flour can be used as a wheat flour substitute in bread, pastries, cookies, and biscuits and as a source of food starch. Because of cassava's huge potential in the global starch market, the focus should be on the production of high-quality food starch, as well as lower value industrial products.

The cassava value chain starts with the production of certified planting materials, followed by primary production, and on-farm processing for the production of semi-processed products, prior to industrial processing. The development of the cassava industry can contribute to food and income security, job creation and revitalization of the rural sector. It can help address the challenges of the high starch demand and provide an avenue for import substitution. The processing industries have a key role in driving cassava development and to engage small and large starch processing enterprises in South Africa. Investment in cassava processing and product development should rely on systematic analysis of opportunities and constraints of cassava at each stage of the commodity development cycle. This can be done by stakeholders that are engaged in the development of the cassava industry that involves producers, processors and consumers, as well as associated national, international and non-governmental organizations. Research and development support is essential to assist to overcome important problems within the production-processing-marketing continuum.

Cassava being a tropical crop, it is highly sensitive to low temperatures below 18°C (Huang et al., 2005). Low temperature causes delayed sprouting of stem cuttings, reduced leaf expansion, low biomass accumulation and decrease storage root yield (Phoncharoen et al., 2019). In South Africa, the growing season is characterized by a hot rainy summer followed by a cold and dry winter. Frost is a major obstacle for cassava production and propagation in South Africa. There are two approaches used by researcher to cope with frost, namely the use of early bulking germplasm or pruning. All the varieties currently in the system are old cultivars that take more than 18 months to mature. Therefore, early bulking cultivars that fit into the growing season (i.e., matures within 7–9 MAP) or cold-tolerant cultivars that can grow in a prolonged growth period are in demand. The Brazilian climatic condition is similar to South Africa. In the higher altitude and moisture prone areas of Brazil, farmers grow cassava in October/November and prune the cassava plant in June to avoid the cold winter. There is variation in cultivars response to pruning in terms of root yield, starch and dry matter content. Some cultivars show a reduction in root fresh yield, dry matter and starch content due to the fact that cassava plants consumed the reserve starch to overcome vegetative bud dormancy during the winter and shoot regrowth during the summer, while other continued the starch accumulation from where it stops with no reduction in yield and starch related traits (Curcelli et al., 2014). These materials are considered to be frost tolerant.

Cassava production in Africa is curtailed by cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) (Legg et al., 2015). CMD is a severe cassava disease prevalent in all cassava growing regions of Africa and India (Legg et al., 2011). However, variation in overall prevalence and in the severity of losses caused by the disease has been reported among regions (Ntawuruhunga et al., 2007). CMD is caused by a complex of diverse whitefly-transmitted cassava mosaic geminiviruses (CMGs) (Patil and Fauquet, 2009). The cassava geminivirus family is composed of at least 11 distinct viruses that have been characterized worldwide, of which seven have an African origin (Kuria et al., 2017). Generally, in Africa the estimated yield losses caused by CMD were reported at 15–24%, representing 15–28 million tons of cassava production (Masinde et al., 2016). The estimated annual economic losses in East and Central Africa are estimated to be between $1.9 and $2.7 billion USD (Patil and Fauquet, 2009).

Cassava brown streak disease (CBSD) was restricted to the lowland coastal areas of eastern Africa (Patil et al., 2015). Recent surveys have shown that CBSD is highly prevalent in Central, Eastern and Southern parts of Africa (Mulenga et al., 2018). It has been reported in Mozambique, Kenya, Uganda, Zambia, and Malawi (Tomlinson et al., 2018). The study by Mbewe et al. (2017) indicated the presence of two distinct virus species. CBSD does not have an obvious effect on the growth of cassava; however, the root necrosis produced by CBSD has caused a reduction in both qualitative and quantitative yield (Alicai et al., 2007) and affects maintenance of planting materials (Ndyetabula et al., 2016). Most of the yield loss from the disease is thought to be the consequence of the loss of root storability resulting from severe root rot (Hillocks et al., 2008). Gondwe et al. (2003) reported 18–25% yield loss by CBSD, while Hillocks et al. (2001) published a yield loss estimate of 70% from the most susceptible variety. Much less attention has been given to the disease compared to CMD, partly due to its restricted geographic distribution. However, recently the high prevalence and distribution of the disease has been reported due to presence of high population of whitefly vector B. tabaci.

In South Africa, market access remains one of the key limiting factors for the development of emerging commercial and smallholder farmers; some institutional and technical constraints to market access in SA are well-documented (Van Schalkwyk et al., 2012). The Market for agricultural produce is largely controlled by a handful of corporate companies with excessive regulatory and compliance requirements that are beyond the means of emerging farmers. To exploit the socio-economic potential of cassava, unlocking market access and developing the entire value chain are critical. Work must start on the following key aspects to ensure the creation of sustainable market;

The ARC has already embarked in some of the aspects described above. It should be noted that there are encouraging signs that there are farmers and farmer groups ready to embark on cassava production and beneficiation. The Authors of this article have received request for production support in the form of variety choice and agronomic support in Limpopo, KwaZulu-Natal province and Mpumalanga provinces. However, ensuring market access has paramount importance before large-scale production is resumed.