Embracing Biological Control of Septoria Tritici Blotch for Sustainable Wheat Protection

Wheat, one of the top-produced cereals worldwide, is affected by many abiotic and biotic stresses, such as the ascomycete fungus Zymoseptoria tritici, the causal agent of Septoria tritici blotch (STB). STB has historically been managed with fungicides, but the pathogen readily overcomes chemical control because of its rapid genetic evolution. In addition, many fungicides are now being banned or limited by governments aiming for more environment-friendly methods for pest management. This scenario gave rise to thinking about alternative control means such as biological control agents (BCAs) and organism-derived biomolecules (ODBs). In this work, we review microbial BCA candidates and ODBs currently studied for the control of STB. Key studies have identified successful candidates including bacterial strains of the genera Pseudomonas and Bacillus, and fungal strains such as Trichoderma harzianum, Penicillium olsonii and Acremonium alternatum. In addition, lesser-studied fungi, bacteria and compounds have been tested. Despite promising research, no BCA or ODB has been registered or commercially used against STB, and field trials are notably lacking, with existing studies being limited in scale. Further understanding of the interactions between Z. tritici and the wheat microbiome may uncover new potential candidates for STB biocontrol.