Farmer-Friendly Method Controls Banana Xanthomonas Wilt Disease

Bioversity International, the International Institute of Tropical Agriculture (IITA) and the Institutional Learning and Change (ILAC) Initiative under the umbrella of the CGIAR Research Program on Roots, Tubers and Bananas (RTB) are collaborating on efforts to get banana farmers in Eastern and Central Africa to adopt a new approach to managing banana Xanthomonas wilt (BXW) that enables them to contain that devastating disease without having to destroy large amounts of plants. Widespread adoption of this ‘single diseased stem removal’ (SDSR) technique has the potential to bring the disease under control while saving labor and money.

Field of bananas infected with Xanthomonas wilt, a devastating bacterial disease found only in Eastern Africa.

Field of bananas infected with Xanthomonas wilt, a devastating bacterial disease found only in Eastern Africa.

BXW first struck East Africa in the early 2000s, and by 2004, 33% of farms in Uganda were infected and yield losses were estimated to be 30-52%. Agricultural extension officials advised farmers to remove all infected ‘mats’ (two or more banana stems growing together) and replant with clean planting material. While this strategy proved effective, it is costly, labor-intensive and results in a major loss of food and income – not to mention banana biodiversity – so many subsistence farmers resisted implementing it.

Scientists from IITA and Bioversity collaborated with Uganda’s National Agricultural Research Organization on field studies at a site in Kifu, Uganda from 2008 -12 to assess the systemicity of the bacteria that causes BXW in plants and mats. The results indicated that few stems in an infected mat will show disease symptoms. The researchers also noticed that some farmers who were reluctant to destroy entire mats of bananas had resorted to cutting only the visibly infected plants, and continued to harvest bananas.

While IITA began work to develop BXW-resistant bananas in Uganda, a Bioversity team led by scientist Guy Blomme tested a management approach using SDSR in eastern DR Congo. They began at the village of Katana centre, in South Kivu, where BXW incidence averaged 80% in February 2013.

Within one month, BXW incidence had dropped to below 10%, and within three months of application, it was below 2%. “Results across the pilot sites are very consistent,” said Blomme. “If farmers cut all diseased shoots off at soil level, incidence can easily be kept below 1%.”

By the end of 2014, SDSR was being evaluated on 540 smallholdings across 10 pilot sites in South and North Kivu and initial results showed that SDSR can reduce disease incidence from as high as 90% to less than 1% in 6 to 10 months.

The Katana pilot site now serves as a demonstration farm where more than 500 representatives of government agencies, NGOs and farmer associations, and individual farmers have learned about the technique.

“We show them photos of what the site looked like two years ago. It’s like day and night,” Blomme said.

The control package was fine-tuned through transdisciplinary research conducted in South Kivu in 2013 and 2014 by a team that included social and biophysical scientists from ILAC and Bioversity who analyzed results together from agronomic and social science perspectives.

The researchers worked with farmers’ groups to test the recommended package under farmer conditions. Results in farmer-managed plots showed that SDSR and sterilizing machetes with fire after cutting diseased stems could keep incidence below 1% under the agro-ecological conditions of South Kivu.

“Our results have all sorts of implications, not only for scaling out SDSR but also for research priorities,” said ILAC coordinator Javier Ekboir. He added that the team reached conclusions that will facilitate the tailoring of the SDSR package to different agro-ecological conditions and identified general principles for the implementation of transdisciplinary research.

Blomme noted that BXW poses a major threat in Burundi and especially in North and South Kivu. FAO studies have found that the disease is moving into the Congo Basin, where millions more depend on bananas and plantains for food and income.

The good news is that government agencies and NGOs are interested in promoting SDSR.

In September 2014, Bioversity and IITA researchers gathered with government and NGO representatives in Kampala, Uganda to plan a RTB initiative for managing BXW that includes both SDSR and breeding for resistance.

The workshop resulted in an impact pathway for improving management of BXW and catalyzed greater cooperation around the issue. Emmanuel Njukwe, an associate scientist at IITA, said that many workshop participants attended a follow-up meeting in Bukavu, South Kivu, after which the FAO and the DR Congo National Institute for Agronomic Study and Research began organizing monthly meetings on BXW in South Kivu with more than a dozen organizations.

“We have been doing a lot of training in stakeholder workshops and we are trying to engage policy makers so that we have synergy and an approach to scale out this technology,” he said.

The provincial branch of the DR Congo Ministry of Agriculture in North Kivu has already commissioned a BXW management project based on SDSR. RTB scientists are helping the international NGO Food for the Hungry to promote the SDSR package in South Kivu.

They are providing comparable support for Catholic Relief Service’s BXW work in Burundi’s Muyinga province, where Bioversity and ILAC will collaborate on further transdisciplinary research to determine the most appropriate management strategy for that region.

RTB scientists envision promoting SDSR and other BXW management options to half a million smallholders who currently lose up to one third of their banana production to the disease – equivalent to an annual loss of more than US$200 million.

This will be accomplished by partnering with government agencies, NGOs and farmer associations, as well as through linkages to the CGIAR Research Program on Integrated Systems for the Humid Tropics (Humidtropics) R4D and innovation platforms.

Further scaling is underway with other Ugandan and DRC stakeholders involved in the RTB Results Based Management (RBM) pilot. The RBM pilot is an initiative wich started in 2014 with a grant awarded to RTB by the CGIAR Consortium.

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