ANTAGONISTIC INTERACTIONS BETWEEN Trichoderma spp. AND Phytophthora palmivora (Butler) FROM OIL PALM IN COLOMBIA

Bud rot is the most critical disease in Colombian oil palm crops. In addition to implementing current management strategies, it is necessary to search for alternatives to control this disease. This work aimed to assess in vitro the antagonistic activity of 12 isolates of Trichoderma spp. (seven native, three commercial and two donated) against one isolate of Phytophthora palmivora, the causal agent of bud rot. To determine the potential of these isolates in biological control, their competitive abilities, mycoparasitic interactions and the antibiotic properties of their metabolites against P. palmivora in vitro and detached leaf tissue were assessed. The seven native isolates were molecularly identified by partial sequencing of the ITS region and TEF1. As result, in the mycoparasitism tests, coiling, entangling of pathogen hyphae, and colonization of pathogen sporangia were observed. Also, the strain CPTrZC-02 displayed the highest frequency of interactions with pathogen hyphae (55%) and sporangia (63%). For the volatile metabolite activity, inhibition of the diametrical growth of P. palmivora was found, with percentages between 12.8 and 32.2%. For the non-volatile metabolites, the development of P. palmivora was limited, with inhibition percentages between 81 and 98% for isolates CPTrZC-05, CPTrZC-02 and CPTrZC-04. The crude extract from CPTrZC-09 inhibited the development of pathogen lesions at a rate of 100%. The native isolates were identified as Trichoderma reesei (CPTrZC-04), Trichoderma harzianum (CPTrZC-09), Trichoderma asperellum (CPTrZC-05 and CPTrZC-12), and Trichoderma asperelloides (CPTrZC-01, CPTrZC-10, and CPTrZC-11). The isolates T. reesei, T. harzianum, and T. asperelloides, due to their properties, are promising for further field assessments as part of a comprehensive management plan for bud rot in Colombia.