An early detection tool has been developed that could help West African countries tackle cocoa swollen shoot virus.
Cocoa Swollen Shoot Virus (CSSV) is spreading rapidly in Côte d’Ivoire, Ghana, Nigeria, and Togo, in response to which the World Cocoa Foundation (WCF) has developed an early detection tool which has the potential to safeguard the livelihoods of millions of farmers in the region.
CSSV is a plant virus endemic to West Africa that attacks all stages of the cocoa plants, from seedlings to young and mature trees, and is responsible for the Cocoa Swollen Shoot Virus Disease (CSSVD).
When a cocoa tree is infected, it takes a while for symptoms to manifest themselves and three years for the tree to completely die. As a result, farmers may inadvertently spread the disease by sharing infected planting materials or through grafting and transferring infected germplasm. This is the main cause of the rapid spread of the virus in Côte d’Ivoire, Ghana, Nigeria, and Togo. The only known cure is cutting and destroying infected trees.
In August 2018, the governments of Côte d’Ivoire and Ghana announced a concerted, joint control effort to combat CSSVD. They described the threat posed by CSSVD as comparable to natural disasters like tsunamis and earthquakes and urged producers to allow their farms to be treated.
As Hervé Bisseleua, Director of Agricultural Productivity at WCF explained, the virus has already infected 16.5% of Ghana’s cocoa areas (more than 300,000 hectares) and the government is planning on investing an estimated US$33 million to replace 22,850 hectares of infected cocoa farms across the country over the next two years. The government of Côte d’Ivoire will cut more than 100,000 hectares of infected cocoa farms in the next three years, which will cost an estimated US$19 million. The prevalence of the disease is not yet well-known, and neighbouring countries like Cameroon may soon be infected.
WCF believes that the key to CSSVD eradication is early detection, both in planting material, before seedlings reach farms, and on existing trees, before symptoms occur. This should be part of an integrated approach to identification, management, cutting out of infected farms, replanting, and diversification.
The early detection tool will soon be deployed in Côte d’Ivoire. It combines real-time polymerase chain reaction (PCR ) and DNA-based genetic testing (a plant is declared diseased if the DNA of the virus is present).
A handheld PCR device is used to screen samples in the field, and only a few samples are sent to a specialized laboratory for DNA testing. The process requires a robust sampling protocol for farms and nurseries to ensure proper analysis of the disease presence and its spread.
WCF is coordinating a regional programme supported by the governments of Cameroon, Côte d’Ivoire, Ghana, Nigeria, and Togo, development partners, and the private sector to make a concerted effort to fight the disease and its spread.
(photo: World Agroforestry Centre)