Downy mildew caused by Peronosclerospora spp. is a major disease of maize (Zea mays L.), and Trichoderma spp. are widely used as biological control agents against this pathogen. This study aimed to determine the effect of two Trichoderma spp. isolates propagated on different media on the incidence of downy mildew in maize. The study was conducted at the Biological Control Agent Laboratory of the West Java Plantation Protection Agency and in a field in Pasirbiru Village, Rancakalong District, Sumedang Regency, from April to May 2025. A Completely Randomised Factorial Design with two factors, isolate type (Trichoderma spp. from BBPOPT and BBPPTP) and propagation medium (cracked corn and rice bran), replicated five times, was used in the laboratory. At the same time, a Randomised Block Design was applied in the field to evaluate effectiveness against downy mildew. The propagation medium significantly affected the reduction in medium weight before and after inoculation, with rice bran reducing medium weight by up to 1.20 g. The BBPOPT and BBPPTP isolates grown on maize medium produced the lowest numerical AUDPC values (128.33 and 122.50, respectively) and the highest numerical disease suppression (42.8% and 45.40%, respectively), although differences among treatments were not statistically significant. These results indicate that Trichoderma spp. treatments delayed early-stage disease development but did not significantly suppress overall downy mildew progression. As field evaluation was conducted at only one location and season, further multi-location, multi-season studies are needed to confirm the consistency of these effects