Figure 1: BBTD infected banana plants in the West Nile region ( W. Ocimati) Source: authors Figure 2: BBTD aphid vectors ( G. Ogwal) Source: authors POLICY BRIEF Tackling Banana Bunchy Top Disease in Uganda I. CONTEXT AND IMPORTANCE Bananas and plantains (Musa spp.) — hereafter referred to as banana(s) — are a critical staple, food security, and economic crop in Uganda. Uganda has the world’s highest daily per capita banana consumption (~0.7 kg) [1] and ranks fourth in global production and first in Africa’s banana production [1,2,3]. Around 11 million tons of East African Highland Bananas (for cooking and beer production) are annually produced by about 47% of Ugandan smallholder farmers on around 2.5 million hectares .This represents a gross annual production value of more than US$65 million [3,4]. Banana bunchy top disease (BBTD) (Figure 1), caused by banana bunchy top virus (BBTV), poses an increasingly severe threat to Sub-Saharan banana production, particularly to that of Uganda [4]. In 2021, BBTD was first reported in the West Nile region in northwestern Uganda [4,5], and more recently in the Kasese district (Rwenzori subregion) bordering the Democratic Republic of Congo [6,7], where it is widespread in both areas. The disease is spread through infected planting materials and locally by the banana aphid, which is omnipresent in banana production landscapes (Figure 2) [9,10]. 2 POLICY BRIEF Figure 3: Predicted environmental suitability for possible wider BBTD spread, under current climate. Values shown reflect BBTD occurrence probability. Source: authors II. KEY FINDINGS [1] 1. What is the current BBTD status and impact? • BBTD was present in Uganda for over four years prior to detection. It is present in at least 9% of farms in northwestern Uganda and Kasese district. In Kasese, the prevalence is about 97% in the most-affected sub-counties of Karambi and Mpondwe-Lubiriha Town council. Affected farmers have reported up to 100% loss in yields and incomes, and often the abandonment of banana production. 2. How vulnerable is Uganda’s banana production system? • The above-mentioned modeling confirms a heightened BBTD risk within Uganda’s major banana growing areas [1,11]; (Figures 3 & 4), with a high risk of the disease spreading to other banana production zones in Uganda. Low-altitude areas, such as those near Lakes Victoria, Edward, and Albert, exhibit high vulnerability due to favorable conditions for BBTD and the presence of its aphid vector. Rising temperatures and projected climate change are expected to exacerbate the risk [1,4,8,9], with mid- and high-altitude regions becoming increasingly vulnerable (Figure 4). Epidemiological research, disease vulnerability modeling [1,11] (Figures 3 & 4), and monthly project/partner reports in 2024 all offer new insights that confirm a heightened BBTD incidence risk and offer help to tackle this growing threat. These research findings and the field experiences summarized below should be integrated in the national and even regional BBTD prevention and mitigation strategy. < 1 1 - 5 5 - 10 10 - 15 15 - 20 20 - 25 25 - 50 50 - 75 > 75 3. What are the current levels of awareness about the disease? • The level of awareness, knowledge on symptoms, epidemiology, and disease control are low among scientists and extension staff, and lacking among banana farmers. This, coupled with: i) heavy reliance on local suckers for planting; ii) lack of effective quarantine; and iii) limited resources for implementing appropriate control measures, increases the risk of BBTD spread. 4. What risk is posed by movement of banana planting materials? • Our study [1] revealed a high frequency in the use of suckers sourced from individual home gardens or within communities, and a low frequency in the use of clean planting materials, such as tissue-cultured plants. Currently there are no quarantine measures being implemented to prevent the movement/exchange of planting materials. 5. What management practices are farmers currently using? • Farmer responses to infected plants in their gardens/ farms were found to vary [1]. Practices such as complete rogueing (removing diseased banana mats, i.e. cluster of stems arising from physically interconnected corms) were underutilized. Disease prevalence is linked to using infected suckers as planting materials. 6. What are the recommended management practices? • Regularly removing old/dried leaves to prevent aphid population build-up. • Applying a soapy and/or plant extract solution on infected and neighboring mats to immobilize or kill aphids before uprooting the diseased mats. • Firstly, uprooting all infected mats (rogueing) and composting plant debris for later use as manure. Corm pieces should not be buried, but instead left to dry on the ground in a sunny location. Secondly, using clean planting materials to re-populate cleared areas (see point 2 of the Policy Recommendations—Clean Planting Materials). 7. What lessons can we learn from other countries? • The disease is difficult to control once it is established. • BBTD severely affects banana productivity, leading to significant yield and economic losses of up to 100% for farmers [10]. BBTD almost wiped out the banana industry in Australia between 1913 and 1920 [12], while it reduced the banana production area in Malawi from 3,500 ha to 800 ha in the 1990s [13]. 3Tackling Banana Bunchy Top Disease in Uganda III. POLICY RECOMMENDATIONS These research findings should be integrated into a new national and even regional BBTD prevention and mitigation strategy. Such a strategy should align with other national and regional BBTD control initiatives [14], including the recent coordination efforts by the African Union’s Inter-African Phytosanitary Council (AU- IAPSC) and the Food and Agriculture Organization of the United Nations (FAO). The integrated BBTD management strategy should include: 1. SURVEILLANCE AND QUARANTINE: i. Strengthening disease surveillance and imposing quarantine measures in affected areas to prevent further spread of BBTD. ii. Monitoring regions identified as high-risk, particularly in the southwestern region of Uganda. iii. Integrating predictive risk mapping to better target quarantine, surveillance, and mitigation efforts [1]. 2. CLEAN PLANTING MATERIALS: i. Promoting the use of certified, disease-free planting materials, and establishing local clean seed systems for farmers. ii. Restricting the movement of planting materials from infected areas. iii. Ensuring BBTD containment policy aligns with broader national and regional policies. 3. CAPACITY BUILDING FOR BBTV DIAGNOSIS, SURVEILLANCE AND MANAGEMENT: i. Training agricultural extension officers and farmers on BBTD detection, surveillance, monitoring, and timely reporting of BBTD incidence. ii. Enhancing farmer and extension worker training on BBTD prevention and control measures, such as correct rogueing techniques and disposal of infected material. • Enhanced knowledge of BBTD epidemiology and management will trigger a more rapid response in the field, if and when new infections are observed, preventing further spread of the disease. Awareness campaigns will also foster citizen involvement in disease surveillance and management (linked to point 7). 4. POLICY SUPPORT FOR INTEGRATED BBTD CONTROL i. Supporting active policy enforcement. ii. Restricting the movement of planting materials from affected regions to mitigate long-distance spread. iii. Strengthening regulatory measures to enforce quarantine and manage aphid populations. iv. Providing policy support for advice on sources of clean planting material. Strengthening policy to guide banana seed multipliers in producing healthy banana planting material (in vitro-derived plantlets, macro-propagation-derived plantlets, suckers). v. Considering clean planting material certification once this becomes possible. vi. Ensuring BBTD containment policy aligns with broader national and regional policies. vii. Forming a national task force of key stakeholders, for technical consultations and regular surveillance and monitoring BBTD spread at country level. 5. SUPPORT FRAMEWORKS TO BUILD POLICIES FOR DISEASE MANAGEMENT AT GRASSROOTS LEVEL, INCLUDING INVESTMENTS IN RESEARCH FOR: i. BBTD-resistant banana varieties. ii. BBTD epidemiology and control measures, including approaches to suppress aphid populations. 6. CLIMATE ADAPTATION STRATEGIES: i. Incorporating BBTD control into broader agricultural climate-resilience programs. Figure 4: Likelihood of BBTD establishment and spread within different landscapes in Uganda, under current climate. Source: authors 4 POLICY BRIEF 7. PUBLIC AWARENESS: i. Launching awareness campaigns that involve communities in disease surveillance and reporting, and also emphasizing the economic and nutritional importance of bananas. IV. CONCLUSION BBTD presents an increasingly significant challenge to Uganda's food security and agricultural economy. Proactive measures focusing on prevention, management, and farmer education are critical to limiting its spread and safeguarding banana production landscapes. Collaborative action by government agencies, researchers, and farming communities is essential to addressing this urgent threat. Such a strategy should align with other national and regional banana disease-control initiatives [12], including the recent coordination efforts by AU-IAPSC and FAO. V. REFERENCES 1. Ocimati W; Ogwal G; Tazuba AF; Kubiriba J; Tugume J; Erima R; Okurut W; Mahuku G; Kutunga D; Blomme G. (2024). Mapping the vulnerability of banana production landscapes in Uganda to banana bunchy top disease. Front. Agron. 6:1401478. https://doi.org/10.3389/fagro.2024.1401478 1 2. Uganda Bureau of Statistics. (2020). Uganda annual agricultural survey 2018. Kampala, Uganda: UBOS. 3. FAO (Food and Agriculture Organization of the United Nations). (2024).Crops and livestock products. https://bit.ly/3WGj7lY 4. Feed the Future. (2018). Available online at: https://www.feedthefuture.gov/country/uganda/ 5. Ocimati W; Tazuba AF; Tushemereirwe WK; Tugume J; Omondi BA; Acema D; Were E; Onyilo F; Ssekamate AM; Namanya P; Kubiriba J; Erima R; Okurut AW; Kutunga D; Blomme G. (2021). First report of banana bunchy top disease caused by Banana bunchy top virus in Uganda. New Disease Report 44, e12052. https://doi.org/10.1002/ndr2.12052 1 The research reported in this paper has generated this Policy Brief. 6. Ocimati W. Unpublished results. 7. Amanyire S. (2024). Banana disease threatening food security in Kasese. New Vision. https://bit.ly/3CHhZrg 8. Nakato GV; Okonya JS; Kantungeko D; Ocimati W; Mahuku G; Legg JP; Blomme G. (2023). Influence of altitude as a proxy for temperature on key Musa pests and diseases in watershed areas of Burundi and Rwanda. Heliyon 9, e13854. https://doi.org/10.1016/j.heliyon.2023.e13854 9. Niyongere C; Ateka E; Losenge T; Blomme G; Lepoint P. (2011). Screening Musa genotypes for banana bunchy top disease resistance in Burundi. Acta Horticulturae 897, 439–447. https://doi.org/10.17660/ActaHortic.2011.897.60 10. Niyongere C; Losenge T; Ateka EM; Ntukamazina N; Ndayiragije P; Simbare A; Cimpaye P; Nintije P; Lepoint P; Blomme G. (2012). Understanding banana bunchy top disease epidemiology in Burundi for an enhanced and integrated management approach. Plant Pathology 62, 562–570. https://doi.org/10.1111/j.1365-3059.2012.02676.x 11. Bouwmeester H; Blomme G; Omondi AB; Ocimati W. (2023). Banana bunchy top disease in Africa — Predicting continent‐wide disease risks by combining survey data and expert knowledge. Plant Pathology, 72(8), 1476-1490. https://doi.org/10.1111/ppa.13764 12. Magee CJ. (1927). Investigation on the bunchy top disease of bananas. Bulletin of the Council for Scientific and Industrial Research in Australia No. 30. Melbourne, Australia. 13. Soko MM; Dale J; Kumar PL. (2009). Banana bunchy top disease survey reports, previous control efforts and the way forward. Limbe, Malawi: Agricultural Research Station. 14. BBTD Alliance. (2024). Disease Control. Banana disease framework for containing emerging disease spread in sub-Saharan Africa. https://bit.ly/3WHrGgf https://doi.org/10.3389/fagro.2024.1401478 https://www.feedthefuture.gov/country/uganda/ https://doi.org/10.1002/ndr2.12052 https://bit.ly/3CHhZrg https://doi.org/10.1016/j.heliyon.2023.e13854 https://doi.org/10.17660/ActaHortic.2011.897.60 https://doi.org/10.1111/j.1365-3059.2012.02676.x https://doi.org/10.1111/ppa.13764 https://bit.ly/3WHrGgf 5Tackling Banana Bunchy Top Disease in Uganda ACKNOWLEDGEMENTS The authors wish to acknowledge the contributions of the authors of the main research paper that led to the development of this policy brief, namely, W. Ocimati, G. Ogwal, A. F. Tazuba, J Kubiriba, J Tugume, R Erima, W Okurut, G Mahuku, D Kutunga, and G. Blomme. Financial support is also recognized from the CGIAR Initiative on Plant Health and Rapid Response to Protect Food and Livelihood Security. The policy brief was developed by Joab Tugume (MAAIF, Uganda), Patrick Odongo Ikoku (NARO, Uganda), Vincent Johnson (consultant), Walter Ocimati (Alliance Bioversity & CIAT) and Guy Blomme (Alliance Bioversity & CIAT). We thank Olga Spellman (Alliance Bioversity & CIAT Science Writing Service) for copy editing, and Vicky Rengifo (Alliance Bioversity & CIAT Publications, Branding, and Graphic Design) for design and layout. CIAT December 2024 The Alliance is part of CGIAR, a global research partnership for a food-secure future dedicated to reducing poverty, enhancing food and nutrition security, and improving natural resources. CIAT CONTACT Joab Tugume (MAAIF, Uganda), joabtugume@gmail.com Patrick Odongo Ikoku (NARO, Uganda), pat4ikoku@yahoo.com Walter Ocimati (Alliance Bioversity & CIAT), w.ocimati@cgiar.org George Mahuku (The International Institute of Tropical Agriculture), g.mahuku@cgiar.org alliancebioversityciat.org https://www.cgiar.org/initiative/plant-health/ CITATION Tugume J; Odongo Ikoku P; Johnson V; Ocimati W; Blomme G. (2024). Tackling Banana Bunchy Top Disease in Uganda. 6p. mailto:joabtugume%40gmail.com?subject= mailto:pat4ikoku%40yahoo.com?subject= mailto:w.ocimati%40cgiar.org?subject= mailto:g.mahuku%40cgiar.org?subject= http://alliancebioversityciat.org