Antifungal and growth activity of strains of Trichoderma spp. against the Avocado “tristeza” disease, Phytophthora cinnamomi

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Background Avocado “tristeza,” a disease caused byPhytophthora cinnamomi, is one of the main limiting factors of avocado production in the Caribbean region. To control the pathogen, the application of agrochemicals is required, but this has caused environmental problems.Trichodermaspp. present properties in promoting plant growth and controlling phytopathogens, being proposed as an alternative to replace chemical fertilizers. The objective of the study was to evaluate the antagonistic activity ofTrichodermaspp. againstP. cinnamomiand its possible potential for promoting plant growth in vitro. Soil samples were taken from avocado cultivars from the municipalities of Ovejas (Sucre-Colombia) and Chalán (Sucre-Colombia). Results Serial dilutions were carried out for the isolation ofTrichodermaspp. Once the strains were purified, the antagonism test againstP. cinnamomiwas carried out in PDA culture medium. For growth promotion, SRS medium was used for phosphate solubilization and CAS medium for siderophore production. DNA extraction and identification of the isolates were performed using the tef1 gene.Trichoderma harzianumandT. asperellumpresented a 93.4% inhibition against the pathogen, followed byT. viridewith an inhibition of 83.5% and finallyT. longibrachiatumwith 78.4% inhibition, showing significant differences in the control of the growth of the pathogen (p < 0.05) and promoted plant growth. These species release enzymes that can degrade the cell wall of the pathogen causing its death or inhibit its growth through the production of secondary metabolites. Conclusions The results showed that the application ofTrichodermaspp. in crops confers protection against pathogens and stimulates the growth of plants to obtain a high yield.