Identification of Phytophthora spp. isolates obtained from cocoa crops in Antioquia, Colombia

With the aim to identify the Phytophthora species associated with black pod and stem canker diseases of cocoa in Antioquia, 120 isolates were evaluated using morphological and molecular approaches of Phytophthora spp. isolates obtained from pod, stem, and soil samples collected in 11 municipalities. Morphological characters in sporangia and chlamydospores, formation of sexual structures, pattern and growth rate of the colonies, and cardinal temperatures were evaluated. Molecular identification was done by conventional PCR and qPCR. The 120 obtained were identified as Phytophthora, 119 isolates belong to P. palmivora, and the strain CH6-3S was not associated with any Phytophthora species previously reported as a cocoa pathogen. A multidimensional scaling model based on morphological attributes showed a wide diversity in the size and shape of the sporangia (eight morphotypes). However, variability among isolates was low (17 %), and the formed subgroups do not correspond to locations, nor to the tissue type from which they were obtained.