Virulencia de <i>Phytophthora</i> sp en brotes de cacao (<i>Theobroma cacao</i> L.) a nivel <i>in vitro</i>

Phytophthora sp. is a significant phytopathogen that affects fruits, stems, leaves, and shoots of cocoa (Theobroma cacao L.), causing considerable yield losses. The characterization of pathogenic strains is very useful to optimize disease management. For this reason, the objective of this study was to evaluate the virulence of Phytophthora sp. in cocoa shoots under controlled in vitro culture conditions. Initially, a morphological characterization of Phytophthora isolates was carried out. Subsequently, this phytopathogen was inoculated into disinfected shoots of two cocoa varieties: Nacional fino de aroma and CCN-51, following a completely randomized factorial design with seven replications, using the shoots as experimental units. Phytophthora sp. is a significant phytopathogen that affects fruits, stems, leaves, and shoots of cocoa, causing considerable yield losses. The variables evaluated included incidence, severity, resistance, and the area under the disease progress curve, which were evaluated daily for four days. Identification of the genus Phytophthora sp was performed through molecular testing using internal transcribed spacer primers ITS4-ITS6. The results showed that the incidence and severity in National Fine aroma cocoa shoots reached 100% when infected with strain PP8, evidencing a high susceptibility to the disease known as black pod. In contrast, CCN-51 cocoa shoots did not show any infection by the strains evaluated. It is concluded that the virulence of Phytophthora sp. depends specifically on both the pathogen strain and the host. These findings highlight the importance of considering the phenotypic variability of the pathogen and host resistance to effectively manage fungal diseases in cocoa crops.