From risk to weapon: Composting transforms phytopathogen-contaminated vegetable waste into a sanitized and disease-suppressive fertilizer

The increase of vegetable cultivation areas and frequent plant diseases caused by continuous cropping have made the disposal of phytopathogen-contaminated vegetable waste a pressing problem that needs to be solved. The study carried out a composting experiment of Fusarium oxysporum - contaminated cucumber residues amended with sawdust, sugarcane bagasse, or Chinese herbal residues, in which pathogen concentration was 10 4 CFU/g. Pathogen presence did not disrupt the core biodegradation dynamics of the composting process. After 18 days of composting, the pathogens were effectively removed across all treatments. Sugarcane bagasse emerged as the optimal amendment, as it delivered an 85.47% Fusarium oxysporum f. sp. Cucumerinum (FOC) removal rate and superior maturity (germination index, GI >80%). Integrated multi-modal analytics revealed that carbon amendments regulate FOC suppression (83.33~85.47%) via bacillus-mediated pathways and ammonia emissions, while pH governs GI through organic acid conversion. All treatments developed disease-suppressive microbiomes enriched with Bacillus , Aspergillus , and Penicillium, and also showed reduced occurrence of soil borne diseases. Network analyses confirmed functional redundancy despite pathogen-induced taxonomic shifts. This work establishes a circular economy paradigm where composting transforms phytopathogen-contaminated vegetable waste into a sanitized and disease-suppressive fertilizer. • High pathogen load (10 4 CFU/g DW) in PCVW would not inhibit the composting process. • Disease suppression by infected-waste compost matched that from healthy residues. • qPCR and culturing indicated effective FOC reduction (<300CFU/g, unculturable). • Composting proceeded effectively despite a high initial pathogen load (10 4 CFU/g DW). • Biocontrol-enriched compost microbiomes suppress pathogens in vitro.