A Comparative Analysis of Soil Morphology under Cocoa Trees Infected with Swollen Shoot Disease in the Subprefectures of Bouaflé and Kononfla, Central-West of Côte d’Ivoire

Abstract

In Côte d'Ivoire, cocoa farming is one of the most important agricultural activities in the country's economy. However, the economic success of cocoa farming is severely threatened by numerous constraints, the most decisive of which is swollen shoot disease, leading to a significant decline in production over the years. The various solutions considered to date are generally limited to uprooting cocoa trees and have neglected the soil, the natural support for the crop. The reality is that the disease persists and is gaining ground. In the search for a solution, this study sets as its overall objective of highlighting the link between soil factors and swollen shoot. This study involved conducting a morpho-pedological analysis in the two areas made up of Bouaflé and Kononfla, which are an integral part of Marahoué, a region with a high endemicity of this disease. In fact, the morphophysical properties of soils under healthy cocoa trees are compared to those of soils under infected cocoa trees. Two experimental plots measuring 100 m × 100 m were established at each site, and slope was measured using a clisimeter. Morpho-pedological characterization was conducted in field pits to evaluate key physical and hydromorphic properties using standard field and laboratory methods. The results from all sites show a similar level of development. The main differences observed in infected plots include a higher concentration of iron-rich concretions and bad internal soil drainage, as well as an accumulation of sand or silt between 20 and 40 cm deep in diseased plots. In contrast, healthy plots showed deeper hydromorphic limits (beyond 120 cm) and better soil permeability. These results allow us to conclude that the quality of the cultivation soil conditions the appearance of the disease in the cocoa tree. The soil physical constraints, particularly compaction, textural imbalance, and shallow waterlogging, may contribute to cocoa tree weakening and increase susceptibility to swollen shoot disease, highlighting the importance of soil quality in disease dynamics.