Observations on the Potential of an Endophytic Fungus Associated with Cacao Leaves against Phytophthora palmivora

A study was conducted to test the pathogenicity of an endophytic fungus associated with asymptomatic cacao leaves, to determine its identity through cultural, morphological and molecular characterization, and to evaluate itsantagonistic ability vs. Phytophthora palmivora causing cacao black pod rot disease. Experiments were carried out under laboratory and shade house conditions. Homogeneity of variances and normal data distribution were determined using Bartlett’s and Shapiro–Wilk tests, respectively. Inoculation of the endophyte in healthy cacao seedlings and pods at 5 × 105 to 1 × 106 conidia per mL by spraying resulted in asymptomatic infections. The endophyte was recovered from artificially inoculated tissues 14 and 26 days after inoculation (DAI) (UF18 seedlings), and at 10 (K9 seedlings) and 14 DAI from cacao pods. The endophyte was identified as Colletotrichum siamense based on its cultural, morphological and molecular characteristics. In vitroanti-pathogen assays showed that C. siamense had the potential to limit pathogen growth by antibiosis. At 3, 5 and 7 days after incubation period (DAIP), growth of the pathogen in co-cultivation with the endophyte measured 60.0, 70.0 and 71.0 mm, respectively, which wasconsiderably lower than the growth of the pathogen alone.