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Mirid resistance studies in Côte d'Ivoire : Field observations on recent and cumulative damage

N'Guessan F.K., Eskes A., Lachenaud P.. 2006. In : Eskes Albertus (ed.), Efron Yoel (ed.). Global approaches to cocoa germplasm utilization and conservation : Final report of the CDC/CCO/IPGRI project on "Cocoa germplasm utilization and conservation: A global approach" (1998-2004). Amsterdam : CFC, p. 170-176. (CFC Technical paper, 50).

A study was conducted in Côte d'Ivoire with the objectives of firstly, classifying the major genetic groups of cocoa based on the level of resistance or susceptibility to cocoa mirids, and secondly, identifying promising genotypes within each genetic group. All the genotypes were evaluated on the basis of recent and cumulative mirid damage in a field collection. A score of 0 (no damage) to 4 (severe damage) was given to each genotype. The results showed that there were significant differences between the major genetic groups of cocoa with regard to mirid damage. The Upper Amazon, wild Guianan and hybrid genotypes were the least damaged by the mirids. The scores of these groups of cocoa varied between 0.1 and 0.3 for the recent damage; and between 0.4 and 0.8 for the cumulative damage. The Catongo group was by far the most susceptible group. This group had scores of 2.3 for recent damage and 2.0 for cumulative damage. The Amelonado, near Criollo and Trinitario groups were also found to be susceptible but to a lesser extent. Promising genotypes were identified within each group.

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