Graphene Oxide Has Inhibitory Effects on Diverse Soil-Borne Pathogens

Soil-borne diseases pose a major threat to global vegetable production, yet effective and environmentally friendly control strategies remain limited. In this study, the inhibitory effects of graphene oxide (GO) were systematically investigated against six soil-borne pathogens: three formae speciales of a single fungal species, Fusarium oxysporum (f. sp. niveum, cucumerinum and lycopersici), one bacterial pathogen (Pectobacterium carotovorum), one protist (Plasmodiophora brassicae) and one nematode (Meloidogyne incognita). In vitro assays demonstrated that GO exhibited concentration-dependent inhibition across all pathogens. At 200 mg·L−1, GO reduced mycelial biomass by 64–68%, spore germination by 38–44%, and colony diameter by 13–21% across three Fusarium formae speciales. GO also suppressed P. carotovorum colony-forming units by 65% and increased M. incognita mortality to 59.4%. Notably, GO showed exceptional efficacy against P. brassicae, reducing root hair infection by 86.2% and inhibiting dormant spore germination by 85.6%. In pot experiments, GO applied at 100 mg·kg−1 soil significantly reduced Fusarium wilt incidence and clubroot incidence by 59.8% and 57.3%, respectively. qPCR analysis confirmed that GO treatment reduced the abundance of target pathogens in soil. These results indicated that GO was a promising nanomaterial for the integrated management of soil-borne diseases.