The second step of the priority assessment exercise comprised the description of research options and adaptable output. Groups of resource persons described the research options that were selected in the Kampala workshop and subsequently assessed through the economic surplus model and cost-benefit analysis.
Click the links to find out more about each constraint, how RTB research addresses the constraint, status of research, adaptable innovations, expected impacts and target regions and systems.
| Constraint | Banana bunchy top disease (BBTD) is one of the most devastating diseases of banana and plantain particularly for smallholders (Dale 1987). BBTD, caused by the banana bunchy top virus (BBTV), produces erect, narrow, short brittle leaves with yellow borders and typical dark green streaks on leaves and pseudostems and stunted suckers. It results in very small or no bunches (i.e., complete yield loss). Infected mats eventually die, but often remain as a source of inoculum. The disease spreads through infected suckers and via the banana aphid (vector). BBTD is widespread in Asia. The first cases of BBTD in sub-Saharan Africa (SSA) were reported in 1958, with an increase in the rate of spread in the last decades. The disease is now found from southern Malawi and Burundi/Rwanda/eastern Democratic Republic of the Congo (DRC) all the way to Nigeria, Central African Republic (CAR), and Benin (Kumar et al. 2011). While laboratory techniques for virus detection and development of BBTV-free planting materials are well established, neither of these services nor commercial sources of BBTV-free planting material are available in rural areas of Asia and Africa. |
| (Potential) RTB research | Generation of alternative practices, models, decision tools, and technologies for use in different land-use systems:
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| Status of research | The research will build on extensive knowledge and field experience generated in Asia and the incipient experience in SSA. The focus of new research will be to build a more robust understanding of BBTV, its vector, and the interaction both with host diversity and with farmer practice and the surrounding agricultural system. Pilot sites will also be set up to generate tools for building community capacity to recover from BBTD destruction and to mobilize containment when BBTD is first identified. This represents a major research initiative, since most BBTD recovery to date has focused on commercial monocrop plantations. The estimated completion time for the research is nine years with a research success rate of 90%. |
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| Target region/system | Focus is on AAA-Cavendish and other AAAs in Asia (Philippines, Taiwan, Vietnam, Sri Lanka) and on diverse smallholder perennial systems of AAA EAHB and plantain (AAB) in West and Central Africa (DRC, Republic of Congo-Brazzaville, Equatorial Guinea, Cameroon, CAR, Gabon, Benin, Nigeria); East Africa (Burundi, Rwanda); and Southern Africa (Malawi, Angola), although other minor cultivar groups in the same areas would also be affected |
| Constraint | The rapid spread of banana Xanthomonas wilt (BXW), caused by Xanthomonas campestris pv. musacearum, endangers the livelihoods of millions of farmers in East and Central Africa who rely on banana as a source of food and cash (Tushemereirwe et al. 2004; Tripathi et al. 2009). It is mainly transmitted via contaminated farming tools, insects acting as vectors, and infected planting material. Unchecked, the disease can destroy entire banana plantations. The pathogen infects all cultivated banana varieties in Eastern and Central Africa (ECA), including East African Highland bananas (AAA-EAHB), plantains, Pisang Awak and exotic types. Overall economic losses in ECA have been estimated at over US $2 billion over the past decade in ECA, due to price increases, significantly reduced production, and revenue losses (Abele and Pillay 2007). In Central Uganda alone, yields declined by 80–100% between 2003 and 2008 due to infections of BXW in Pisang Awak, with corresponding income loss and higher prices of banana beer. In affected areas, banana production has declined by more than 50%. Effects on AAA-EAHB highland production in the Kivu provinces of eastern DRC have been catastrophic due to lack of institutional infrastructure and knowledge dissemination networks. The disease has reportedly spread farther toward the southern parts of South Kivu (Uvira and Fizi) and the Oriental province in DRC. BXW has spread across 15 of the 17 provinces in Burundi over a two-year period. Many farmers are still unfamiliar with disease symptoms and control options. In addition, the current control options are highly labor intensive, expensive, and time consuming, limiting adoption. |
| (Potential) RTB research | Evaluation and dissemination of genotypes escaping insect vector transmission; better understanding of host-pathogen interaction for more easily adoptable control packages; develop stakeholders’ platforms for delivery of clean planting materials; raising public awareness to enhance adoption. |
| Status of research | Research on improved cultural practices for management of BXW is ongoing, and the current effort started in the year 2003. Past experiences have shown that is it very important to develop cultural practices in a participatory manner to ensure the technology package is attractive for adoption (Blomme et al. 2014) and does not conflict with resource (time, tools, knowledge, capital) limitations common for smallholder farmers (see, e.g., Jogo et al. 2011, 2013). A technology package will be developed, tested, and ready for adoption in seven years, with an estimated research success of 90%. |
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| Constraint | The rapid spread of banana Xanthomonas wilt (BXW), caused by Xanthomonas campestris pv. musacearum, endangers the livelihoods of millions of farmers in East and Central Africa who rely on banana as a source of food and cash (Tushemereirwe et al. 2004; Tripathi et al. 2009). It is mainly transmitted via contaminated farming tools, insects acting as vectors, and infected planting material. Unchecked, the disease can destroy entire banana plantations. The pathogen infects all cultivated banana varieties in Eastern and Central Africa (ECA), including East African Highland bananas (AAA-EAHB), plantains, Pisang Awak and exotic types. Overall economic losses in ECA have been estimated at over US $2 billion over the past decade in ECA, due to price increases, significantly reduced production, and revenue losses (Abele and Pillay 2007). In Central Uganda alone, yields declined by 80–100% between 2003 and 2008 due to infections of BXW in Pisang Awak, with corresponding income loss and higher prices of banana beer. In affected areas, banana production has declined by more than 50%. Effects on AAA-EAHB highland production in the Kivu provinces of eastern DRC have been catastrophic due to lack of institutional infrastructure and knowledge dissemination networks. The disease has reportedly spread farther toward the southern parts of South Kivu (Uvira and Fizi) and the Oriental province in DRC. BXW has spread across 15 of the 17 provinces in Burundi over a two-year period. Many farmers are still unfamiliar with disease symptoms and control options. In addition, the current control options are highly labor intensive, expensive, and time consuming, limiting adoption. |
| (Potential) RTB research | Evaluation and dissemination of genotypes escaping insect vector transmission; better understanding of host-pathogen interaction for more easily adoptable control packages; develop stakeholders’ platforms for delivery of clean planting materials; raising public awareness to enhance adoption. |
| Status of research | Development of GM resistant banana is ongoing at several institutions. In 2005, a consortium led by IITA started a project to develop EAHB AAA and AAA banana varieties resistant to BXW. The work is now in its second phase, and resistant varieties will be ready for adoption in eight years (plan to release the resistant variety in 2020), with estimated research success of 90%. |
| Adoptable innovations | GM-resistant varieties of dessert cultivars and East African Highland bananas |
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| Opportunity | Smallholder farmers access (urban) markets with good prices and (growing) demand, especially for off-season production |
| Constraint | Banana yields realized by smallholder farmers are generally low and do not bring high revenues due to suboptimal timing of harvest for two main reasons: (1) farmers are not sufficiently aware and/or responsive to market prices, they have limited market access opportunities, and prices fluctuate largely (seasonality); and (2) farmers are not technically equipped (production system knowledge) or have insufficient resources to produce high yields (at the right time), including pest management practices such as clean and uniform planting material and BLS, improved plant nutrition, irrigation and soil health practices. |
| (Potential) RTB research | Develop an integrated crop intensification package adapted to the local biophysical and socioeconomic environment, including quality planting material, timing of production: sucker/planting (timing for high prices), select suitable varieties (fit for local market and agro-ecology), integrated soil fertility management (ISFM), integrated pest management (IPM), plant densities, irrigation/water management, improved intercrop systems, and postharvest management. |
| Status of research | Ongoing, but new research started in year 2013; technology ready for adoption in five years (2018), with research success of 90%. |
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| Target region/system | Smallholder systems of EAHB in Eastern Africa; AAB plantain in WCA and LAC; Cavendish and other AAA dessert bananas in Asia (excluding major export areas with intensive production); Asia: Bangladesh, Indonesia, Myanmar, Papua New Guinea (PNG), Philippines, Sri Lanka, Vietnam; Africa: Burundi, Cameroon, Cote d’Ivoire, DRC, Ghana, Guinea, Nigeria, Rwanda, Tanzania, Uganda; LAC: Cuba, Dominican Republic, Haiti, Honduras, Nicaragua, Peru |
| Constraint | Infestation with nematodes, weevils, black leaf streak (BLS, Sigatoka), and Fusarium result in substantial yield and postharvest losses in banana production in LAC, Africa, and Asia. |
| (Potential) RTB research | Mitigating losses from the mentioned pests/diseases (namely BLS, nematodes, weevils, and Fusarium) through breeding for (improved) disease resistance and high-quality fruit; research on pathogen population structures. |
| Status of research | Banana breeding has been ongoing at IITA and CARBAP (African Centre for Research on Banana and Plantains), first- and second-generation hybrids with improved disease resistance are available (see, e.g., Lemchi et al. 2005), but room for improvement (distinguish release of existing improved material and new breeding efforts in the assessment). Release of existing material would take some 7 years (some issues with built-in virus), new breeding would result in improved varieties in 17 years, with research success of 100%. |
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| Constraint | Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Pisang Awak, Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB Bluggoe-type cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia, the Middle East and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. Preventing the entrance and further spread of TR4 is the first strategy. Therefore, research actions aiming pathogen exclusion and strengthening quarantine and surveillance measures are necessary. Also included here are measures to eradicate the first plants detected and contain the spread of the disease. |
| (Potential) RTB research | RTB research would comprise the following interventions:
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| Status of research | Research initiatives focusing quarantine and surveillance are limited. There are advances in the production of Foc-free planting material through tissue cultures, but protocols need to be improved to increase the adoption levels. A diagnostic protocol is available for TR4, but not for other Foc strains. Recent concerns about specificity of the TR4 diagnostic for in planta detection have emerged, indicating the need of further improvements. Development of improved quarantine and surveillance measures would take 5 years with an estimated probability of research success of 80%. |
| Adoptable innovations | (Improved) exclusion, surveillance, containment and early eradication measures on farm, community, national and international level |
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| Constraint | Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. While preventing the spread of TR4 should be the first strategy, disease management must be strengthened in parallel. There has been some success with cultural practices to manage Fusarium (in Asia and for R1 in LAC), but long-term research aiming to reduce pathogen inoculum, create suppressive and healthy soils and boosting plant defences are necessary. |
| (Potential) RTB research | Recent research proves that FW can be managed in small plots within acceptable control levels through soil and crop management. However, a better understanding of both disease epidemiology and host-soil-pathogen relationships is necessary in order to generate science-based and scalable management strategies. RTB research would comprise the following interventions:
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| Status of research | A complete crop and disease management package will be developed, tested, and ready for adoption in ten years (partial results will be used by farmers in 5 years), with an estimated probability of research success of 90%. |
| Adoptable innovations | – Crop and disease management package |
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| Constraint | Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. While preventing the spread of TR4 should be the first strategy, disease management must be strengthened in parallel. Currently, no cultivars resistant to TR4 are available, but opportunities exist by exploring germsplasm banks, wild type species already identified with high levels of resistance and somaclonal variation. |
| (Potential) RTB research | RTB research would comprise the following interventions:
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| Status of research | Some clonal variants with quantitative resistance have been identified and currently explored in Asia. However, a remarkable genotype – environment interactions have been also reported. Wild species with full resistance have been identified, but these genes need to be transferred to commercial cultivars. Resistant cultivars would be available in 15 years, with an estimated probability of research success of 60%. |
| Adoptable innovations | High yielding and market accepted Fusarium resistant varieties |
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| Target region/system |
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| Constraint | Global banana production is seriously threatened by the re-emergence of Fusarium Wilt (FW). The LAC region experienced one of the most devastating plant disease epidemics in history. Starting in the 1920s and culminating in the 1950s, FW of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), wiped out large production areas of Gros Michel, the initial export banana from LAC. Foc is particularly devastating, because it remains in the soil for decades. The race of Foc affecting Gros Michel became known as Race 1 (R1) and also affects other cultivars such as Apple, Prata, and Isla. Race 2 (R2) has also been identified that affects certain ABB cooking bananas. The industry circumvented the problem by a shift to R1-resistant Cavendish cultivars, which are currently the source of 99% of banana exports. However, a new highly virulent strain of Foc (tropical race 4-TR4) is now affecting Cavendish plantations in Asia and Africa, threatening the banana industry globally. TR4 also threatens millions of smallholders worldwide because, unlike R1 and R2, it affects most banana cultivars used and based on current shares of cultivars affects 80% of all banana production area (Ploetz 2009, OIRSA meeting). In Australasia an estimated 100,000 ha of commercial banana plantations have been devastated by TR4. As the pathogen persists in the soil for many decades, susceptible varieties cannot effectively be planted ever again. Currently no cultivars resistant to TR4 are available. While conventional breeding offers opportunities and need to be explored, technologies that speed up the development of resistant commercial varieties, such trans/ cis-genic and gene editing must be researched in parallel. |
| (Potential) RTB research | RTB research would comprise the following interventions:
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| Status of research | Technologies to introduce genes in commercial varieties are already available, but the number of candidate genes is still low. In addition, a better understanding of basic principles of plant-pathogen interaction is needed to guarantee broad spectrum and durable resistance. GMO Fusarium resistant cultivars will be ready for adoption in 10 years, with an estimated probability of research success of 40%. |
| Adoptable innovations | High yielding and market-accepted genetically modified Fusarium resistant varieties |
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