Improvement of cocoa tree resistance to Phytophthora diseases

Cocoa black pod rot causes almost 30 % losses in world cocoa production. This disease is caused by various species of the genus Phytophthora. The most harmful species, P. megakarya, is currently invading Ivory Coast, the leading producing country. Faced with this threat, teams of researchers from CIRAD in France, IRAD in Cameroon, CNRA in Ivory Coast and CRU in Trinidad came together in a research project on the genetic bases of cocoa tree resistance to Phytophthora diseases. This research received financial backing from European chocolate makers through the Caobisco association.

This overview presents the results obtained in work undertaken during the project. Its main purpose is to provide the international community with knowledge and tools that can be used to breed cocoa trees with greater resistance to Phytophthora.

Improvement of cocoa tree resistance to Phytophthora diseases covers pathogen diversity, epidemiological knowledge, the genetic parameters of resistance observed in the field, and practical breeding aspects. The relevance of different screening tests involving artificial inoculations and the use of molecular markers for the selection of resistant material are widely covered.