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Fighting lethal yellowing disease for coconut farmers

October 3, 2018

As one of the world’s top 20 coconut producers, Côte d'Ivoire’s local economy depends heavily on the fruit as a source of nutrition, for livestock feed, and for jobs — the majority of which are held by women.

By the time lethal yellowing disease (LYD) was detected in Côte d'Ivoire in 2014, it had already killed more than 8% (over 400 hectares) of coconut groves in the country’s coastal region of Grand-Lahou. Without prompt action, the disease was forecast to decimate the country’s coconut crop by 2020.

Research highlights

  • Discovered phytoplasma, the bacterial parasite behind lethal yellowing disease. Researchers also identified a new leafhopper insect that transmits the disease between coconut palms.
  • Developed practical and environmentally friendly field practices to control the spread of the disease and increase coconut crop productivity and profitability.
  • In greenhouse-based sweet pepper production, appropriate varieties combined with local compost increased yields by more than 100%.
  • Gender-responsive approaches to engage farmers, stakeholders, and policymakers in disease management and control strategies.
  • New tool to predict land use change and to help re-allocate the areas devastated by the disease.

    A two-pronged approach to research

    When researchers identified a bacterial parasite associated with LYD, called phytoplasma, in all of the affected villages, farmers in the Grand-Lahou region finally had an answer as to why their coconut crops had been destroyed. Then attention was quickly turned to preventing the disease’s spread.

    Preventing the spread of LYD required a two-pronged research approach: understanding and controlling the outbreak, and continually sharing new information so that authorities, policymakers, and farmers could act immediately to control it.

    Once the major culprit responsible for spreading the disease was identified — a leafhopper insect (Nedotepa curta) that transmits LYD phytoplasma to coconut palms and other plant species — researchers explored several potential solutions to curb the damage to coconut palms.

    These included naturally strengthening a plant’s defence to LYD by working with microbes that live within plants (endophytes) and in soil; establishing practices for removing weeds that host LYD phytoplasma; and introducing a technique from Ghana that calls for felling diseased trees at an early stage. The most effective method, however, was controlling the proliferation of leafhopper insects. A new species of parasitoid was found to be a practical tool for defense against LYD because the tiny insects infest and destroy the leafhopper’s eggs. Rearing parasitoids is simple and fast, with the potential of providing a new income source for farmers.

    With the identification of LYD and methods to curb its spread established, attention turned to sharing this new information with stakeholders so they could act immediately. Farmers were empowered with the knowledge and tools to detect, identify, and control the lethal bacterium; establish a healthy seednut supply; and generate revenue from other crops and coconut products to compensate for lost revenues.  

    Planning for the long-term

    The new information gleaned from the research was translated into a new disease management plan for LYD; a three-year rehabilitation plan; an environmental and mitigation plan; a farmer field mini-guide; and policy briefs. Researchers transferred a new technology that quickly detects the disease in its early stages to the National Centre of Agronomic Research and the University Nangui Abrogoua in Côte d'Ivoire.

    The project organized 10 field schools to train 1,960 farmers and 180 extension agents on proper coconut farming, marketing, disease management, and seedling supply. The field schools also imparted critical knowledge for establishing coconut nurseries, controlling seed exchange, and managing resistance trials. Lessons also featured demonstrations on how to intercrop coconuts with bananas, apply poultry manure for stronger crops, and sell coconut products in an effort to help farmers, particularly women, improve coconut crop productivity, their family’s nutrition, and to increase incomes.

    In addition, nine plant clinics mobilized more than 670 farmers, villagers, producers, and processors with technical training and advice. For the first time women coconut farmers in Grand-Lahou organized themselves into groups to provide training on coconut farming and maintenance, land preparation, and processing and marketing. The initiative resulted in more than 300 women in six villages planting cassava in areas devastated by the disease as a new source of income.

    An action plan has been developed to continue scaling up these activities into 2020. Ongoing field trials in Côte d’Ivoire and Ghana will continue to identify local palm varieties that are resistant to LYD, as well as the best approaches to support the rehabilitation of the coconut industry in Côte d'Ivoire.

    The Canadian International Food Security Research Fund (CIFSRF) is jointly funded by IDRC and Global Affairs Canada.

    Learn more about this project and its outcomes.