Integrating synthetic community with chemical fungicide improves the control of Rhizoctonia bare patch disease in wheat

The soil borne pathogen Rhizoctonia solani AG8 causes Rhizoctonia bare patch disease, a major constraint on global wheat production, particularly in no- or minimal -till systems. Current control strategies such as crop rotation, chemical fungicides, and tillage provide only partial protection, while fungicides can accelerate resistance development and negatively impact crop, soil, and human health. Microbial biological control agents (BCAs) and synthetic communities (SynComs, combining two or more BCAs) represent a sustainable alternative for managing Rhizoctonia bare patch. However, inconsistent efficacy and limited compatibility with fungicides remain key challenges to adoption. Here, we demonstrated that individual BCAs and a SynCom (comprising Diaporthe sp. and Pseudomonas sp. KAR75) reduced disease incidence at the seedling stage by 51–71% compared with fungicide treatment. When combined with fungicide, disease incidence was further reduced by 65–100%. The BCA treatments also improved grain yield by 9–12% compared with fungicide treatment and by 11–15% compared to no-pathogen control, demonstrating their ability to promote wheat growth in the absence of disease. Grain yield increased most with the fungal-bacterial SynCom, particularly when applied together with fungicide. These results demonstrated that integrating BCAs with chemical fungicides has strong potential to improve control of soil-borne diseases in grain crops.