Abstract BACKGROUND Biocontrol strategies for soil rely on interactions between antagonistic and pathogenic fungi, shaped by competition, antibiosis, and parasitism, especially under nutrient stress. This study compared nitrogen use in phytopathogenic and antagonistic fungi to assess overlap and competitiveness under nutritional limitations. RESULTS The functional response of different fungal isolates (respiratory and biomass production) to nitrogen‐containing substrates was used to calculate niche overlap indices and estimate the competitiveness and nutritional stress between Trichoderma and Verticillium fungal species. Trichoderma isolates exhibited strong competition with Verticillium isolates for some nitrogen nutrients starting from the second day of incubation. Some nitrogenous substrates, such as putrescine and cytidine, were found to be metabolized almost only by Trichoderma , while other chemical species, such as urea and nitrite, were metabolized almost only by Verticillium . Substrates also emerged that both the pathogen and its antagonist can potentially use, but often at a different pace, and finally, compounds not used by either fungal taxa, such as hydroxylamine and ethanolamine. CONCLUSION The calculation of comprehensive indices of niche overlap and stress in fungal strains highlighted different mechanisms of competition between pathogens and antagonists. This highlights the complex dynamics of soil fungi and offers the opportunity of exploiting some fungal ecological mechanisms in an applied context. This includes the preparation of more targeted biocontrol products, based on nitrogenous prebiotic additives. © 2026 Society of Chemical Industry.
Oszust et al. (Thu,) studied this question.