Going against nature

A grower of organic bananas in the Chira Valley, Peru. Banana production is based on one of the largest mono cultures in the world. Credit: www.musarama.org

06/09/2019
pests & diseases | plant genetic diversity

In his latest blog, Juan Lucas Restrepo talks about the importance of identifying collective solutions to diversify our agriculture and thus fight crop diseases such as the dreaded TR4, which originated in South East Asia and is now hitting banana farms in Colombia.

In August, the Instituto Colombiano Agropecuario (ICA) confirmed the devastating news for the banana sector in Latin America: the disease identified in some banana farms in the Colombian region of La Guajira is the dreaded Tropical race 4 (TR4), a strain of the fungus Fusarium oxysporum.

Although the ICA, with the support of guilds, Agrosavia and experts from Bioversity International and other institutions, have developed a timely containment and mitigation intervention, the fact that this disease, which originated in South East Asia, has managed to conquer the Americas sets off alarm bells.

The issue is that banana production, especially for export markets, is based on one of the largest mono cultures in the world, mainly relying on a single variety called the Cavendish. This means that all the plants are genetically similar and, as such, highly vulnerable to diseases like TR4, which can easily break their poor defences.

Fungicide sprayed to protect bananas. While some crop diseases can be controlled by chemicals, currently there are no control measures for TR4. Credit: www.musarama.org

The Cavendish variety is also very vulnerable to other fungi and diseases such as black Sigatoka, which can be controlled by spraying chemicals on crops, with very high economic and environmental costs. TR4, however, cannot be controlled by chemicals and, once infected, the plants will die. It can also stay in the soil for many decades, thus spelling the end of the production of susceptible cultivars in that field. Hundreds of thousands of hectares and jobs, as well as an entire value chain which is worth billions, are put at risk by adopting this monoculture model – an industrial agricultural model which underlies the production of many crops around the world.

While we hope that the work done by the ICA in Guajira will be effective in temporarily containing the progression of the disease, the situation calls for reflection on the risk posed to society by agricultural development that goes against nature, based on populating huge areas with genetic clones such as Cavendish, or by just a few kinds of seeds.

The advance of global warming and climate variability are adding to the risks to farmers, as it goes hand in hand with the outbreak of pests and diseases. Greater agrobiodiversity can also mitigate these challenges.

For instance, Cenicafé worked hard to generate a solution before coffee rust hit plantations in Colombia. As a result, they developed the Colombia Variety and its disease-tolerant successors. These varieties are not monoclonal but rather mixtures of a significant number of different plants, with a similar agronomic performance and almost identical fruits. This strategy in effect provides a shield to protect the crop.

Red bananas for sale at a market in Sri Lanka. In the future, we should be able to find in supermarkets bananas that delight us with a wide variety of flavours and colours. Credit: Bioversity International/D.Hunter

Countries, industry and international entities must unite against TR4 and propose structural solutions. As currently there is not a TR4-tolerant variety similar to Cavendish, we must try other varieties of bananas (and plantains) that are resistant to TR4, but whose appearance and taste are distinct. At the same time, establish a collaborative and robust platform for the genetic improvement of the Cavendish.

In the future, we should be able to find in the fruit section of supermarkets bananas that delight us with a wide variety of flavours and colours and that come from a more diverse and resilient agriculture. Bioversity International safeguards the richest collection of edible and wild species of bananas in Leuven, Belgium, and together with CIAT we are ready to support Latin America and other regions in the design and implementation of new approaches for this and other industries.

Finally, it is worth taking advantage of this situation to understand in which other value chains there are similar risks generated by poor agrobiodiversity. For instance, should the avocado industry rely almost exclusively on the Hass avocado when there are more possibilities? Agrobiodiversity has many of the solutions.

This article is adapted from the original ‘Contra natura’ and reproduced with kind permission from Portafolio. Read the original here.