How can we break tool-mediated spread of Xanthomonas wilt? Wash your garden tools with soap!

Photo by Walter Ocimati

For the past 2 decades, Xanthomonas wilt of banana (aka XW) has severely compromised the livelihoods of millions of banana dependent households in the East and Central African (ECA) region. Where XW has occurred, it has reduced the availability of banana in households and markets; often increased food prices, food and income insecurity; led to loss of key ecosystem services (e.g. erosion control) and in general led to socio-economic insecurity. Like the coronavirus that quickly spreads within a susceptible human population, the bacterial pathogen that causes XW can disperse rapidly through a population of susceptible banana plants.

XW spreads from one plant or farm to another mainly through i) contaminated farm tools, ii) insect vectors foraging for nectar, sap and pollen, and iii) infected planting materials. Yield losses can reach 100% if disease management is delayed.

XW spread through cutting tools has been minimized by cleaning them with household bleach or putting them in a fire for 20 to 30 seconds. While effective, many households cannot afford household bleach nor is it readily available in remote rural areas. The use of fire is often not practical. Flaming and heating can damage the metal blade of tools. Farmers fear starting a fire during the dry season, while they find it difficult to start a fire during the wet season.

To break XW transmission, we looked for alternatives to fire and bleach to enable farmers to routinely sterilize their cutting tools. We found one effective method that was all along very obvious, even more so since the beginning of the COVID-19 pandemic: washing with bar soap. Our recent paper shows how washing with soap and detergents or boiling water can effectively clean/sterilize farming tools.

Key messages from the paper

  • Xanthomonas wilt disease of banana and enset (XW) severely compromises livelihoods of households dependant on banana in East and Central Africa.
  • XW has no cure and is currently only managed through cultural practices (cutting single plants or uprooting entire mats and fields jointly with tool sterilization and early removal of male buds).
  • Tool sterilization is poorly adopted, due to the cost and limited access to household bleach and weakening of metal blades of farm tools by fire. This reduces effectiveness of the control packages
  • Washing tools with laundry soaps or detergents or their insertion into boiling water attains similar results to using household bleach.
  • Laundry soaps and boiling water are more readily accessible and cost-effective alternatives and could improve full adoption of the control packages, thus better disease control. 

The paper is open access at this link https://www.frontiersin.org/articles/10.3389/fagro.2021.655824/full