Abstract
Trichoderma spp. are widely recognized as effective biocontrol agents used to control plant pests and reduce reliance on chemical pesticides. This study aimed to evaluate the in vitro antifungal activity of Trichoderma citrinoviride (AUMIC 13831) against five common plant pathogens: Alternaria sp., Aspergillus sp., Colletotrichum sp., Fusarium sp., and Rhizoctonia sp. Antagonistic potential was assessed using dual culture, volatile metabolite, non-volatile metabolite, and slide culture assays. T. citrinoviride exhibited significant antagonism across all methods tested. In the dual culture method, T. citrinoviride effectively inhibited the radial growth of all tested pathogens, showing inhibition percentages ranging from 50.88% ± 0.73 (against Rhizoctonia sp.) up to a maximum of 61.29% ± 1.86 (against Colletotrichum sp.). The non-volatile metabolites extracted from the culture filtrate proved to be the most potent fungistatic mechanism, demonstrating the highest overall efficiency, particularly against Fusarium sp. (80.95% ± 0.92) and Colletotrichum sp. (69.62% ± 0.72). The volatile metabolite assay exhibited moderate fungistatic effects, achieving a maximum growth inhibition of 36.36% ± 0.43(against Alternaria sp.). Furthermore, the mycoparasitic interaction between T. citrinoviride and the pathogenic fungi was confirmed through detailed microscopic observations. T. citrinoviride shows promising in vitro antifungal activity across multiple antagonistic mechanisms. Further studies in planta, toxicological/environmental assessments, and detailed metabolite identification using LC-MS are required to confirm its applicability as a commercial biocontrol agent. Further studies under greenhouse or field conditions are recommended to validate these findings.