Sclerotinia sclerotiorum : a dual‐purpose biological control agent for weed and disease management in pastures and cereal crops

The cosmopolitan phytopathogenic fungus Sclerotinia sclerotiorum (Lib.) de Bary infects many dicotyledonous species, including major crops and weeds. Its virulence toward key pasture weeds and the innate immunity of grasses has motivated research in North America and New Zealand into its potential as a microbial bioherbicide for pastures. Independently, discovery in China that S. sclerotiorum adopts a symptomless endophytic lifestyle in grasses protecting them against fungal diseases has stimulated research into its potential as a cereal crop vaccine. Together, these findings raise the prospect of deploying a single fungal strain as a broad-spectrum biological tool for integrated weed and disease control in pastures and cereals, challenging long-held assumptions about the ecological roles and applied value of this pathogen. We evaluate S. sclerotiorum as the active ingredient of such a dual-purpose biocontrol product using four foundational pillars for success-hypervirulence (efficacy), low production cost, formulation suitability and biosafety. Wild-type strains are sufficiently virulent and competent endophytic mutualists, whereas microsclerotia offer a cost-effective scalable active ingredient alternative to mycelium. Further innovation is needed to optimize industrial-scale production and formulation. To meet biosafety requirements, we propose developing a non-sclerotia-forming strain retaining hypervirulence and endophytic competence. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.