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Lethal Yellowing Disease in Côte d’Ivoire

Published: March 23rd, 2017

Revised: January 29th, 2019

IDRC/DFATD Project Title and Number: Improving livelihoods of resource-poor coconut smallholder farmers threatened by an emerging lethal yellowing disease of coconut in the coastal region of Côte d’Ivoire – ‘Fighting lethal disease for coconut farmers’. No. 107789. Project Dates: August 1st 2014 to January 31st 2017; 2.5 years. Project Budget: $2, 586, 916 CAD. Location of […]

IDRC/DFATD Project Title and Number: Improving livelihoods of resource-poor coconut smallholder farmers threatened by an emerging lethal yellowing disease of coconut in the coastal region of Côte d’Ivoire – ‘Fighting lethal disease for coconut farmers’. No. 107789.

Project Dates: August 1st 2014 to January 31st 2017; 2.5 years.

Project Budget: $2, 586, 916 CAD.

Location of Study: Grand-Lahou, Côte d’Ivoire.

Research Organizations involved in the study: Sporometrics Inc., Canada; National Centre of Agronomic Research (CNRA), Côte d’Ivoire; University Nangui Abrogoua (UNA), Côte d’Ivoire; National Agency for Aid and Rural Development (ANADER), Côte d’Ivoire; Council for Scientific Research Program – Oil Palm Research Institute – Coconut Research Program (CSIR-OPRI), Ghana; University of Toronto, Canada.

Project Leader: Dr. Yaima Arocha Rosete (Sporometrics Inc.).

Principal Investigators in Côte d’Ivoire: Prof. Taky Hortense Atta Diallo (UNA), and Prof. Jean Louis Konan Konan (CNRA)

General Objective:
To provide and communicate new needed information to allow authorities, policy makers, stakeholders and farmers to better control, Lethal Yellowing disease in Côte d’Ivoire.

Specific objectives:
1) To better understand the bio-ecology and epidemiology of the Côte d’Ivoire lethal yellowing phytoplasma, and the environmental and socio-economic impact of the disease on the coconut industry.
2) To develop and adapt control strategies to reduce the impact of the Côte d’Ivoire lethal yellowing.
3) To strengthen local capacity to diagnose, implement and disseminate control strategies, and empowering women’s role in addressing gender inequity in Grand-Lahou.


Coconut (Cocos nucifera L.) plays a paramount role in the export economy of Côte d’Ivoire, which is the top African exporter of copra coconut oil to Europe and West Africa. Coconut production totals 55,000 tons of copra/year equivalent to 550,000,000 nuts/year. Coconut is cultivated on approximately 50,000 ha along the Ivoirian coastal littoral zone, and it is a critical source of employment and income for around 85, 000 smallholder coconut farmers in Grand-Lahou. In 2013, the Côte d’Ivoire lethal yellowing disease (CILY) was officially reported and associated with a phytoplasma, namely 16SrXXII-B, ‘Candidatus Phytoplasma palmicola’-related strains. Lethal yellowing diseases caused by a phytoplasma affect coconut and over 40 other palm species, and have decimated the coconut industries of many countries in Central America, the Caribbean, Africa and South Asia. In Grand-Lahou, over 400 ha of coconut groves have been destroyed by CILY, and other 7,000 ha are under severe threat. A summary of significant research findings, key advances, outcomes and innovative outputs derived from the IDRC-DFATD project is herein provided.

The CILY phytoplasma was confirmed in over 80 % of the CILY-affected coconut palms in Grand-Lahou. Its epidemiological origin and spread was hypothesized from either the Central or West Regions in Ghana, where the Cape St. Paul Wilt Disease (CSPWD) phytoplasma destroyed the coconut industry in the last 20 years. For the CILY phytoplasma, a new leafhopper genus and species, Nedotepa curta Dimitriev was found as its potential vector, and six plant species from five botanical families identified as its alternative hosts, which may play a critical role in disease spread. The CILY phytoplasma was found in 30 % of symptomless palms, as well as, in mixed infection with a phytoplasma of group 16SrI ‘Ca. Phytoplasma asteris’ leading to a more complex epidemiology and control of the disease.

Nine promising coconut varieties were recommended for long-term resistance trials in pilot farms in Grand-Lahou and Ghana. New field and laboratory diagnostics were developed for the early and specific detection of the CILY phytoplasma to support surveillance, plant health, and disease resistance screening. A new disease management plan, and a 3-year rehabilitation plan were generated and delivered to farmers, stakeholders and policy makers as factsheets, a farmer field mini-guide and policy briefs. The assessment of the socio-economic impact of CILY revealed over 90 % of farmer illiteracy, and high inequality levels for women with limited access to land, training and market. An econometric model was developed to predict the land use change of the coconut cultivated area to re-allocating the CILY-devastated areas and help reviving the coconut industry in Grand-Lahou.

Bacterial and fungal endophytes with biocontrol potential were identified for the CILY phytoplasma, as well as, a new bacterial endosymbiont within N. curta, which may be used for a long-term vector control. A new species of parasitoid of the genus Anagrus was identified parasitizing the eggs of N. curta, which opens new ways of vector control, and a new source of income for farmers due to its very easy-to-implement massive rearing. Field management recommendations included intercropping coconut with plantain for a higher revenue, and to apply poultry manure, which boosts flower development and leads to a higher volume of seednuts for farmers.

Nine training-courses on field and laboratory basic diagnosis, and advanced technology for phytoplasma research, and twelve workshops, including Gender Workshops were held in Côte d’Ivoire, Ghana and Canada; one of them with the attendance of the Ministry of High Education and Scientific Research of Côte d’Ivoire. Six Ivoirian MSc students and 1 PhD graduated, and four of the MSc students are already involved in PhD programs. Project scientific results have been presented in three international conferences, and officially published as full research papers in six high impact factor scientific journals.

New approaches were innovated to increase disease awareness in farmers, stakeholders and policy makers, as well as to empower women within the coconut production chain, which included: field schools, plant clinics, Women Groups and Women Coconut Fairs. Eight field schools trained 1,960 farmers (1,568 men, 392 women), 180 extensionists, and around 700 families on farming and disease resistance assessment, which exceeded the expected figures. Ten plant clinics mobilized 671 farmers, villagers, and processors (478 men, 193 women); and addressed plant disease queries not only in coconut, but also in over twenty other crops such as cacao, cassava, citrus, okra, coffee, peanut, yam, beet, plantain, tomato, maize, etc. The Major and Prefect of Grand-Lahou, the Canadian Ambassador in Côte d’Ivoire, Representatives of the Ivoirian High Education and Scientific Research Ministry, and ten village Chiefs attended the plant clinic held at Braffedon in April 2016. Eight Women Coconut Fairs mobilized 550 participants (390 men and 160 women), and allowed new opportunities of marketing and small businesses for them. Women sell out their coconut products, from crafted and food products, cosmetics to home furniture, whose number increased from 14 to 26 (64 %) from 2015 to 2016. Women coconut farmers organized themselves for the very first time in Grand-Lahou in six Women Groups, which are currently planting cassava yards as a new source of income. New recent findings include the identification of the CILY phytoplasma infecting cassava orchards nearby the CILY-affected coconut farms, which impacts directly on food security for the smallholder coconut farmers of Grand-Lahou.

Project outcomes and outputs have significantly contributed to the knowledge of palm lethal yellowing diseases for the phytoplasma community. Results reach out the coconut farming community in Côte d’Ivoire, Ghana, Mozambique, and other countries of Central America and the Caribbean, and South Asia and the Pacific affected by lethal yellowing diseases. Project outcomes and outputs are an example of how well-orchestrated gender and communication strategies were successfully implemented to empower women to support family income and nutrition; and how to engage natural and social scientists, as well as, stakeholders and policy makers in helping farmers to improve their livelihoods, and rescue the Ivoirian coconut industry. The project strengthened collaboration ties among scientists from Canada, Ghana, Italy, France, and Mozambique, and enhanced the international image of Canada supporting research in Africa. Details are provided at COWALY website (


Acknowledgement: This work was carried out with the aid of a grant from Canada’s International Development Research Centre (IDRC),, and with financial support from the Government of Canada, provided through Foreign Affairs Canada (GAC),

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