We evaluated potential synergy between ASD and Trichoderma spp. in suppression of Rhizoctonia root rot (RRR) in radish. A split plot design with three replications was used; main plots were T. harzianum T22, T. asperellum SM1785 and a non-Trichoderma control. Subplots were ASD carbon sources wheat bran, molasses, chicken manure, and mustard greens and two non-amended controls: anaerobic (covered and flooded) and aerobic (not covered or flooded). Carbon sources and R. solani inoculant were mixed with soil, which was placed in pots and flooded, followed by drenching Trichoderma spore suspensions and sealing the pots in Ziploc bags. After three weeks, bags were removed, soil aired for one week and radish 'SSR-RR-27' seeded. RRR severity was lowest in radish plants grown in ASD-treated soil amended with wheat bran, molasses or mustard greens across all Trichoderma treatments. Disease severity was lower in plants treated with SM1785 than with T22 or the non-Trichoderma control across all ASD treatments, and in radish grown in ASD-treated soil amended with wheat bran plus SM1785 compared to ASD-wheat bran or SM1785 alone. Trichoderma populations were significantly reduced compared to the controls only by ASD-mustard greens. ASD-wheat bran and SM1785 acted synergistically to reduce disease pressure. The efficacy of ASD amended with most carbon sources against soilborne pathogens may be improved by addition of one or more ASD-compatible Trichoderma isolates.