Celebrating Success: Zambian Smallholders Combat Cassava Brown Streak Disease (CBSD)
09 November 2024, Zambia: Cassava is a critical crop to Zambia’s economy and food security. According to a 2019 paper, cassava (Manihot esculenta) is one of the most important root staple crops in Zambia. An estimated 30% of Zambians – over four million people – consume cassava as part of their daily diet. Indeed, this crop is so important to Zambia that the reverse side of the five Kwacha currency note features a cassava plant’s leaves and root.
Yet this valuable staple crop is coming under threat. The invasive cassava brown streak disease (CBSD) has devastated crop yields and farmer livelihoods. The disease has seen affected regions report substantial losses in both yield and income. A CABI evidence note on CBSD estimated economic damage to be 55% of total annual cassava production across four traditional cassava growing provinces. This corresponds to monetary losses of over US $500,000 annually and could be more if extrapolated to the whole country. The disease causes, among other things, severe rot in harvested roots and can lead to up to 100% yield losses in susceptible varieties.
CBSD impact on sub-sectors
CBSD also affects several subsectors that rely on cassava. Investment company, Itabwa Investments, Sunbird Bioenergy Zambia Ltd, Zambia Breweries and biofuel manufacturer, Zhongkai International, have felt the effects of CBSD. Collectively, they need over 50,000 tonnes of cassava feedstock annually for biofuels, brewing, confectionary and mining. Cassava starch has been found to work well in copper processing. It is preferred over chemical acids that are typically used because it is also friendlier to the environment. Furthermore, demand from other subsectors is increasing. Market forecasts indicate that cassava starch demand will reach over 10 million tonnes in 2024.
Taking action to manage the spread of CBSD
CABI is working with the Zambian Ministry of Agriculture (MoA) to promote the cultivation of healthier cassava crops, specifically the Department of Agriculture (DoA), the Seed Control and Certification Institute (SCCI) and Zambia Agricultural Research Institute (ZARI).
In August 2022, the government, together with CABI, rolled out a campaign to curb the spread of the CBSD. At a meeting held during the campaign, stakeholders agreed on a response plan. This included better diagnostics and phytosanitation at the community and farm level. It also developed a seed (cutting) system to ensure farmers’ access to disease-free and improved planting materials.
A fundamental challenge that farmers faced is a lack of access to clean cassava cuttings, free from CBSD, which resulted in the rapid spread of the disease through the sharing of diseased planting materials. In 2023, CABI spearheaded a comprehensive training programme in the cultivation of clean cuttings. Seed controller, SCCI, conducted the training. Farmers learned about the correct cultivation and management of the cassava crop. They are now reaping a bountiful harvest of clean cassava cuttings.
The PlantwisePlus roll-out of clean cassava cuttings
In February 2023, through PlantwisePlus, CABI distributed clean cassava cuttings to 516 farmers in the Nsama District of Zambia’s Northern Province. The cuttings have helped smallholders to produce healthy cassava crops free from CBSD. Following the training, 14 ‘lead’ farmers successfully transitioned into registered “seed” growers. Itabwa Investments is already buying cuttings from CABI-trained seed growers. The company is also providing smallholders with anti-termite products and tractors, as well as other inputs, to help improve their cassava production.
PlantwisePlus is working with Zambian farmers helping to manifest the country’s vision of managing CBSD. Now in its roll-out phase, the programme is focusing on the successful implementation of a functional cassava seed system in Zambia. The programme is concentrating in particular on training women and young people in the production of clean cassava cuttings. The aim is to build community resilience against CBSD, through a formal and gender-responsive seed system.
Some of the smallholder farmers have even proceeded to register new cooperatives. They are now able to better position themselves for continued seed production activities in the region.
Reaping the harvests of healthy cassava cuttings
The clean seeds campaign has been a great success. Smallholder cassava farmers in Zambia are celebrating after growing their crops with clean cassava cuttings free from the CBSD menace. Of the 500 farmers in February 2023 who received disease-free cassava cuttings, 70% have reported a “very good crop stand” and say that the crop is “performing well.”
Furthermore, cassava crops from 16 CABI-trained cassava seed growers have been inspected. The yields from 14 of these growers have met the requirements for official SCCI certification. This means the crop is currently fit to sell as virus-free cuttings and can be used to propagate cleaner cassava fields in the region.
Lead farmer, Gabriel Chisenga, said, “These cuttings have improved our cassava farming prospects. We hope to be regional suppliers of clean cassava seed in northern province because of the certification we are getting as seed growers with the help from CABI.”
Itabwa Investments is now looking forward to engaging 2,000 smallholders by the end of their three-year project. The company will work with CABI-trained farmers to maintain the continuity of cassava seed supply to other farmers in the region.
Improving the cassava production process
The initiative to promote clean cuttings among farmers has highlighted traditional cassava production practices. They reveal how cassava is often cultivated using conventional, but less-than-optimal methods. However, these approaches may not be best for achieving high cassava yields. In upcoming interactions with farmers, CABI plans to incorporate new farming guidance. Our focus will be enhancing overall production practices to fully harness the benefits of clean cuttings and boost cassava yields.
CABI recently visited the lead farmers in Nsama who had received cuttings. They discussed opportunities for accessing other inputs like fertilizer and herbicides to complement the potential of the clean cuttings. The farmers requested more face-to-face support from CABI and ZARI to ensure they are on track with their cassava cuttings’ production.
Beyond CBSD: Growing businesses and mitigating other cassava diseases
The initiative in Nsama has also shown how providing clean cassava cuttings could create potential new business opportunities for everyone, including women and young people. These businesses could be taken beyond Nsama district to other districts in other provinces. This focus aligns well with CABI’s mission to make farming more inclusive and to increase farmer training to boost the success of the initiative to provide clean cassava cuttings.
Dr Chapwa Kasoma, Scientist in Invasive Species Management, is based at CABI’s centre in Lusaka. She explained how CABI has also seen proof that planting clean cassava cuttings mitigates the impacts of diseases other than CBSD. The clean cuttings initiative has reduced the effects of other viral diseases, such as cassava mosaic disease. Researchers are looking into causative agents of other pests affecting the crop in the region. Above all, the project has successfully demonstrated that crop pests and diseases can be managed effectively through an integrated pest management (IPM) approach involving the use of clean planting material.
Discover more information about PlantwisePlus’ work in Zambia here
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