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By Dr. Mathew M. Abang
Bananas represent one of the most consumed and traded fruits globally. In Southern Africa, bananas serve both as a staple food and important cash crop. To date, Tanzania is the largest producer of bananas in the Southern African Development Community (SADC) region, followed by the Democratic Republic of Congo (DRC).
Most bananas grown in southern Africa belong to the Cavendish variety, even though other dessert varieties are also produced. Production is mostly for local consumption, while Cavendish banana exports mostly from Mozambique, take place regionally and internationally. Commercial growers of Cavendish varieties in Mozambique, Eswatini, South Africa, Zambia and Zimbabwe obtain their planting material from tissue culture laboratories and implement advanced cultivation practices to obtain yields of more than 40 tons/ha.
Threat to investment
Commercial production of bananas is capital intensive but all of that investment is severely threatened in Southern Africa by a recently introduced damaging Banana Fusarium wilt disease described as Tropical Race 4 (TR4).
Banana Fusarium wilt disease, caused by a soil-borne fungus scientifically denominated as Fusarium oxysporum f. sp. cubense (Foc), gained prominence when it caused such enormous damage to the popular banana variety Gros Michel that the international banana export industry was forced to switch its entire production to the Cavendish variety, which is resistant to the race of Fusarium wilt that was responsible for the disease outbreak. The form of Foc that affects Gros Michel is designated race 1, while race 2 affects Bluggoe banana and race 4 affects Cavendish bananas.
In the 1990s a form of Foc was reported that severely affected newly planted commercial
Cavendish plantations in Indonesia and Malaysia. This form became known was Foc TR4 and is the most devastating of all the Foc strains as it affects a much broader variety of banana cultivars than previous strains of Fusarium wilt.
Counting losses in Mozambique
In a study published in 2020, which was partly funded and co-authored by the Food and Agriculture Organization of the United Nations (FAO), Prof Altus Viljoen and colleagues reported the occurrence of Foc TR4 in northern Mozambique and described the spread of the fungus in affected Cavendish banana farms between 2013 and 2018. This represents the first scientifically confirmed report of the presence of Foc TR4 in Africa (http://www.scielo.org.za/pdf/sajs/v116n11-12/19.pdf).
Within 4 years of its discovery in northern Mozambique, Foc TR4 destroyed more than 700 000 Cavendish banana plants at the Matanuska farm, which led to the liquidation of the farm in 2018. The liquidation of the farm represented the loss of an investment of about USD 80 million plus the forfeited future income from banana production.
Besides the direct impact, there was an indirect impact on the livelihood of the people working at the farm, which was considerable as more than 2 500 people lost their jobs. Moreover, the affected company had to discontinue the health care and education that it provided to the local communities. The damage caused by Foc TR4 contributed to increased poverty in the area, food shortage and less trade opportunities, with important social and political implications.
The spread of Foc TR4 beyond the boundaries of infested farms in northern Mozambique could threaten the banana-based livelihoods and food security of half a million people, as all bananas produced by large and small-scale commercial and backyards or home garden growers are susceptible to the fungus.
A transboundary pest with no remedy
There are numerous reasons to be concerned about the spread of Foc TR4 in Southern Africa and beyond. Once introduced into a field, the fungus can survive in soil for decades, killing all susceptible banana varieties planted.
There is no cure for Banana Fusarium wilt TR4, and the only means to manage the disease is to introduce quarantine measures (legislation) to prevent the movement of planting materials from infested to non-infested areas, and to plant resistant banana varieties. None of the popular banana varieties grown in the SADC region, however, are resistant to Foc TR4. This probably explains why Foc TR4 is recognized by SADC as one of the five priority plant pests/diseases that constitute a serious transboundary threat to crop production in the region.
Invest in prevention and early detection
There is the real possibility of FocTR4 spreading from the infested farms in northern Mozambique into other parts of the country and to neighbouring SADC countries. To deal with this possibility, three strategies to manage the disease have been proposed. These include, (1) the prevention of introduction into new areas by proper awareness campaigns, farm border control, and the use of clean planting and field materials; (2) the early detection and containment of new outbreaks, which involves routine scouting and the appropriate isolation of newly infested field sites; and (3) the management of the disease by planting disease-resistant varieties and applying good agricultural practices, including soil and water management.
Collective effort – how Mozambique has succeeded
The national response to the outbreak of Foc TR4 in Mozambique has been exemplary and sets high standards. The presence of Foc TR4 in northern Mozambique prompted the Department of Agriculture and Food Security to introduce quarantine measures that restricted the movement of plants and planting material off the affected farms, and the transport of fruit outside the Nampula and Cabo Delgado Provinces.
Strict containment measures were introduced at both Metocheria and Lurio farms, which included gate control, the use of disinfectants, and the issuing of footwear to all workers and visitors. Only farm vehicles were allowed to enter plantations. Farmworkers, communities, and plant protection officials were trained in symptom identification, and awareness programmes were launched. The strict implementation and effectiveness of quarantine measures announced by the Mozambican government should be continuously monitored.
Given the difficulties in managing the disease, these measures should be a collective effort involving policymakers, growers, and the scientific community, and should be implemented on local, national, and regional levels. Strengthened international collaboration, particularly with regards to enhanced data collection and information sharing, will further support improved awareness, prevention, and containment of Foc TR4.
FAO support
At the global level, FAO and the World Banana Forum host the Foc TR4 Global Network as a platform for stakeholder collaboration as well as a knowledge hub for awareness and prevention of the spread of the disease (https://www.fao.org/tr4gn/about-the-tr4gn/en/).
Within the framework of the project ‟Support towards operationalization of the SADC Regional Agricultural Policy (STOSAR)” financed by the European Union and implemented by FAO, a regional training workshop was organized to strengthen the capacity of National Plant Protection Organizations of the 16 SADC member states in the sustainable management of banana Fusarium wilt Tropical Race 4.
The training of trainers (ToT) workshop was conducted in partnership with Stellenbosch University, which is a regional center of excellence on Foc TR4. Following the ToT workshop, laboratory equipment and consumables were provided to the 16 SADC member states to strengthen national capacities in plant disease diagnosis and monitoring for effective disease management. FAO is providing support for countries in the region to conduct surveillance and submit banana samples to Stellenbosch University for identification.
In addition, the southern Africa regional strategy for sustainable management of FocTR4 has been developed, and will soon be validated and approved by the SADC Committee of Ministers of Agriculture.
FAO and Stellenbosch University are assisting SADC member states to develop their national strategies for the control of Foc TR4. The implementation of regional and national Foc TR4 strategies will ensure a harmonized approach and coordinated action in the response to this serious transboundary disease threat.
The regional and national strategic plans will serve as working documents to guide stakeholders at both the regional and national levels to implement plant protection activities for the prevention of Foc TR4. They offer guidelines on how to report, investigate and identify suspect plants. The strategic plans propose ways to develop, legislate and regulate sanitary and phytosanitary policy on Foc TR4, and to communicate a national contingency plan with producers, government officials, the community and neighbouring countries.
Developing capacities
For the implementation of the national strategic plan, technical and regulatory human capacity needs to be developed, and funding made available for the implementation and execution of the plan.
A proper pest risk analysis for Foc TR4 in Mozambique and Africa is required in the event that the fungus spreads beyond the borders of the two affected farms. FAO and Stellenbosch University are collaborating to assess possible pathways of entry for the pathogen in selected SADC member states and develop pest risk maps.
Banana cultivars and production areas that can be affected need to be identified, potential pathways of spread determined, and the risk of the fungus spreading to these areas managed. Resistant banana varieties in Mozambique and Africa still need to be identified, and the possible spread of Foc TR4 in Mozambique needs to be continuously investigated.
Strong political will is needed, as well as commitment and proper investment in plant biosecurity and phytosanitary actions to deal with Foc TR4. To effectively deal with Foc TR4 in the SADC region, legislation should be introduced and enforced by plant protection officials to regulate the movement of planting materials, soil and water off infested farms.
Strict phytosanitary and biosecurity practices should be introduced, and the development of the disease monitored through regular surveillance and reporting. All suspect cases should be reported immediately. To implement a Foc TR4 confinement strategy, scientists, plant health officials and extension workers should be trained in laboratory and field diagnostics, and in disease management.
Mathew M. Abang (PhD, MBA) is the Plant Production and Protection Officer at the Sub-regional Office for Southern Africa of the Food and Agriculture Organization of the United Nations (FAO)
