<![CDATA[Pathogenic fungi remain a major constraint in horticultural cultivation, necessitating effective and environmentally friendly biological control solutions. This study evaluated the antagonistic ability of Trichoderma sp. isolated from spent mushroom (Volvariella volvacea) substrate against six horticultural pathogens F. oxysporum from shallot and chili, Sclerotium rolfsii, Rhizoctonia solani from rice, Colletotrichum sp., and Rhizopus stolonifer from strawberry in vitro using the dual culture method within a completely randomized factorial design with four replications. Parameters measured were percentage inhibition of radial growth (PIRG), daily growth rate (LPH), and area under the colony growth curve (AUCGC), analyzed using the Kruskal Wallis test followed by Dunn's Bonferroni post hoc test (α = 5%). Trichoderma sp. suppressed all tested pathogens, with the highest PIRG against the chili isolate of F. oxysporum (59.97%) and the lowest against S. rolfsii (34.58%). S. rolfsii exhibited the highest LPH and AUCGC values, indicating high colonization aggressiveness with the weakest suppression response. Microscopic observations confirmed mycoparasitism, marked by hyphal coiling and lysis, and antibiosis, indicated by clear inhibition zones. Consistent statistical grouping across all parameters demonstrated stable suppression capacity, with effectiveness varying according to pathogen aggressiveness, indicating that Trichoderma sp. from spent mushroom substrate holds potential as a biofungicide for horticultural pathogen control.]]>
