Harnessing Bioagents for Managing Major Soilborne Diseases of Groundnut- Mechanisms and Future Directions: A Review

Groundnut production is affected by several diseases, among which soilborne diseases pose significant management challenges due to the persistence and survival of their causal pathogens in soil. This review focuses primarily on stem rot and collar rot, two major soilborne diseases of groundnut, while incorporating evidence from other relevant soilborne diseases and pathogens where necessary to provide a broader understanding of biological disease management. Relevant literature was identified through searches of Google Scholar, Scopus and Web of Science using combinations of keywords related to groundnut, soilborne diseases, stem rot, collar rot, biological control, bioagents, PGPR, rhizosphere interactions and biofilms and relevant peer-reviewed studies were critically evaluated. The review critically examines the potential of microbial bioagents, including fungal and bacterial antagonists, plant growth-promoting rhizobacteria (PGPR), microbial consortia and the potential role of microbial biofilms in managing soilborne diseases of groundnut. Particular emphasis is placed on the mechanisms underlying biological disease suppression, including antibiosis, competition, mycoparasitism, hydrolytic enzyme production, induced plant defense responses and rhizosphere colonization. Available evidence from in vitro, pot, greenhouse and field studies is critically examined to distinguish antagonistic activity from demonstrated disease suppression and to identify factors influencing bioagent performance under field conditions. Although several microbial bioagents have shown promising potential against soilborne pathogens of groundnut, their efficacy is influenced by strain characteristics, environmental conditions, colonization ability, formulation and application methods. Future research should prioritize mechanistic validation in groundnut, improved microbial formulations and delivery strategies, multi-location field evaluation and the development of compatible microbial consortia for integration into sustainable disease management.