Cocoa swollen shoot virus

The causative agent of this disease is Badnavirus deltainflatheobromae, a member of the Caulimoviridae family. This viral pathogen is considered one of the most critical threats to global cocoa production, as it leads to progressive decline and eventual death of infected cacao trees.

The primary host plant affected by this virus is the cacao tree (Theobroma cacao). The disease is particularly prevalent in West Africa, where it has necessitated the destruction of millions of trees to curb the spread of the virus across major plantations.

Symptoms of the infection manifest as distinct swellings or galls on the stems and branches of the tree. Foliage symptoms vary widely and can include chlorotic patterns, vein clearing, and leaf mosaic. Infected trees exhibit significantly reduced fruit yield and eventually lose their ability to produce pods altogether.

The virus is transmitted in nature by mealybugs, which act as vectors while feeding on the sap of infected trees. The spread is facilitated by the movement of these insects within the canopy. Secondary spread can occur through contaminated grafting material, although insect transmission remains the most significant factor.

Management of the disease requires comprehensive phytosanitary strategies because there is no known cure for infected trees. The focus is placed on prevention and containment:

• Systematic eradication of diseased trees and surrounding contact trees.
• Development and planting of virus-tolerant or resistant cacao varieties.
• Implementation of robust quarantine measures to prevent regional movement.
• Active management of mealybug populations within the plantation.