West African Farmers Test Early Detection Method for Cocoa Disease

Cacao is a fragile crop, extremely vulnerable to pests and diseases that can significantly impact its yield. According to the International Cocoa Organization (ICCO), some estimates put losses as high as 30 to 40 percent of global production, compromising the livelihoods of smallholder farmers and causing major concern for the global cocoa and chocolate supply chain.

Some of the most destructive diseases include Black Pod Rot, caused by the pathogen Phytophthora spp. and present in Africa, Brazil and Asia; Witches’ Broom, caused by the fungus Moniliophthora perniciosa and present in Latin America; and Cacao Swollen Shoot, caused by the at least 10 species of badnaviruses and present in West Africa.

Other issues particularly affecting West Africa include Loranthus, a genus of parasitic plants that grow on ageing cocoa trees, and Mirids (Distantiella theobroma and Sahlbergella singularis), the most important insect pest of cocoa in West Africa, causing annual crop losses of about 25% in Ghana and 30-40% in Côte d’Ivoire.

Long-standing problem with no known cure

Cocoa Swollen Shoot Disease (CSSD) is one of the most prevalent issues affecting cocoa plantations in West Africa and has been causing serious losses to farmers since it was first discovered in Ghana in 1936.  According to a press release issued by the Ghanian government in 2020, “a survey of the country’s cocoa farms in 2017 revealed that out of the total national cultivated cocoa area of 1.95 million hectares, about 17% of the cocoa tree stock was affected by CSSV disease and 23% was overaged.”

Until now, science has been unable to find a cure that would help the 14 million households in West Africa who rely on cocoa as their main source of income. However, early detection could enable farmers to control the spread of the disease, while the infection is not yet visible.

On-site, early detection brings hope to the cocoa industry

A new testing method is now bringing hope to the cocoa supply chain. Built on SwissDeCode’s DNAFoil proprietary technology, and incorporating underlying research from Mars Wrigley, the new solution is an easy-to-perform testing kit that enables field personnel to quickly test cocoa trees, using their leaves as samples.

In July, Mars and SwissDeCode organised focus group discussions in Côte d’Ivoire to get first-hand input on the in-field test kit from farmers, agronomists, sustainability managers and exporters.

Cocoa producers were excited when introduced to the new tool, which is easy to use and delivers results quickly, and showed interest in using it on their farms.

“For me this is a welcome tool if it can help us to really detect the disease before it is visible – it could help a lot of the farmers in the bush,” said one producer.

The simple test can be performed on-site and has the potential to help safeguard farmers’ incomes, as it gives them an early warning and more time to prepare to face the consequences of the disease.

“If the farmer already knows that in two or three years time his farm could be destroyed by the swollen shoot, he can already start working on a plan B,” comments one sustainability and traceability manager.

The potential impact of this new tool should not be underestimated, as one producer said: “Swollen shoot killed all the cocoa, only five hectares remain of the fifteen I started with. Without the rice and manioc we planted, we would have nothing to eat.”

One tool, multiple applications

The cocoa supply chain is complex and, in order to improve the response against Swollen Shoot disease, several processes and organizations must work together in a coordinated way. Beyond detecting infected trees in the field, the new testing method has the potential to also aid in:

• certification of nurseries as virus-free
• mapping the spread of CSSD
• surveillance of non-infected areas
• monitoring of seed and clonal gardens for early detection
• monitoring of remediated farms – for early detection of possible re-infection

While scientists continue the quest for a cure for CSSD, this tool can provide cocoa producers with a valuable early warning system that could save millions of cocoa trees.

The DNAFoil CSSD test is currently being validated in the field and will soon be made available to all companies in the cocoa supply chain.