Banana Xanthomonas wilt (BXW)—a bacterial disease spread by insects, birds, bats, larger animals, and farm tools—is the biggest constraint for banana production in East and Central Africa. Since its appearance in Uganda in the early 2000s, BXW has spread rapidly in the region, causing food insecurity and income loss. Bioversity International and IITA have collaborated with Uganda’s National Agricultural Research Organization, the Democratic Republic of Congo’s National Institute for Agronomic Study and Research, and other partners on basic research, field testing options for controlling BXW, and scaling-out effective control approaches.
African NARS initially recommended destroying all banana ‘mats’ (2–20 plants growing together) with BXW symptoms and replanting with clean material, but many smallholders resisted this approach because of the labor and hardship caused by production loss. Bioversity International scientist Guy Blomme conducted field studies that showed farmers could reduce incidence of the disease to less than 2% within months by removing only infected banana plants, which requires less labor and income loss than complete mat removal. That approach, called single diseased stem removal (SDSR), is part of a BXW control package that Bioversity International, IITA, and partners are promoting in several SSA countries. The approach also includes the early removal of male buds to prevent insects from infecting plants with the bacteria, and sterilizing farm tools after contact with diseased plants.
RTB is supporting greater regional cooperation around BXW and results-based management of efforts to scale out control measures, monitor their effectiveness, and use gender research to enhance their impact. This has included baseline studies of 900 households in eastern DR Congo and 1,217 households in Uganda, where sex-disaggregated data were collected to shed light on differences between men’s and women’s application of BXW control measures. Banana pest and disease surveys were also completed in Burundi and Rwanda during the dry and rainy season, in collaboration with the UK research agency Fera to draft a pest risk analysis document for BXW.
Bioversity International and IITA work with NARS, agricultural ministries, farmer organizations, and non-governmental organizations (NGOs) to tailor control measures to local conditions and farmers’ needs. Whereas commercial farmers prefer removing entire mats, subsistence farmers have adopted SDSR. Bioversity International researchers estimated that the latter approach results in individual household income recovery of USD115/acre a year.
While BXW control initiatives often include establishing seed systems to multiply and disseminate disease-free planting material for replanting, researchers have recently determined that symptomless banana suckers sourced from infected plots can be used as planting material within BXW-affected zones. This is an option for farmers in areas where clean planting material is unavailable.
IITA and Bioversity International collaborated with FAO on a project in Burundi, Rwanda, and DR Congo that educated farmers about BXW control options and facilitated the propagation and dissemination of clean planting material for improved varieties. Bioversity International produced a video on BXW in several languages, and distributed 5,000 copies together with printed materials to national programs and NGOs for use in training activities. According to IITA agronomist Emmanuel Njukwe, in 2016 more than 15 NGOs promoted BXW control methods such as SDSR and early male-bud removal in these three countries.
According to Njukwe, many local banana varieties are so tall that bud removal is difficult for farmers, which hinders efforts to control the disease. IITA is consequently promoting the cultivation of shorter hybrid varieties (FHIA 17, FHIA 21, and FHIA 25) that were developed in Honduras decades ago and are distributed by the International Transit Center and Bioversity International. Though they are not BXW resistant, the hybrids are easier to keep from becoming infected with the disease. And because they produce large bunches of bananas that are good for local uses, they are quite popular in the region. Consequently, IITA is working with the private sector and farmer cooperatives in Burundi, DR Congo, and Rwanda to scale up the supply of clean planting material for those hybrid varieties.
Image: An excerpt from a poster developed by Bioversity International and FAO promoting the SDSR technique.