The effect of cane molasses amendment on biocontrol of frosty pod rot (Moniliophthora roreri) and black pod (Phytophthora spp.) of cocoa (Theobroma cacao) in Panama

Frosty pod rot (FPR), caused by Moniliophthora roreri, and black pod (BP), caused by Phytophthora spp., of cocoa (Theobroma cacao) cause combined pod losses of more than 80% in Panama. Biological control of both diseases appeared promising in Peru and is desired by certiWed organic producers in Panama. We evaluated both local and Peruvian fungal antagonists in participatory trials on smallholdings during two complete production cycles. Furthermore, we tested the inXuence of a 3% v/v cane molasses amendment on biocontrol eYcacy, yield and population dynamics of mycoparasites on the cocoa pod. SigniWcant variation was observed between the two years: FPR was more severe in the Wrst year, BP in the second. FPR was signiWcantly reduced by biocontrol agents (BCAs), but not by the molasses amendment. However, BCAs responded diVerently to molasses in both years. All BCAs reduced inoculum production by M. roreri with no consistent eVect of molasses. BCAs had a lesser and more variable eVect on BP, whereas molasses reduced BP slightly by increasing the eYcacy of native antagonists. All BCAs and the molasses amendment enhanced the percentage of healthy pods. Molasses was beneWcial to absolute yield, but only one inoculum improved yield signiWcantly in the Wrst year. Populations of a Peruvian Trichoderma asperellum isolate remained high for over two months after application to surface-sterilized pods. Molasses had no eVect on establishment or survival of this antagonist or recolonization by any native mycoparasite. The reasons for enhanced biocontrol eYcacy of the molasses formulation requires further investigation. (Résumé d'auteur