Effective mitigation of sclerotium rot in lettuce cultivation by two soil fungi Aspergillus terreus and Albifimbria verrucaria

Abstract BACKGROUND Lettuce is widely cultivated for its high nutritional value, but its yield is significantly diminished by Sclerotinia sclerotiorum , a pathogenic fungus responsible for Sclerotinia rot. The overuse of chemical fungicides has led to resistance and environmental concerns. Consequently, there is an urgent need to develop effective biocontrol agents as a safer and more sustainable alternative for managing this disease. RESULTS Aspergillus terreus strain JH92 and Albifimbria verrucaria strain JH96, isolated from lettuce fields, exhibited inhibition on the mycelial growth and sclerotia formation of S. sclerotiorum . Crude extracts of both fungal strains demonstrated broad‐spectrum antifungal activity against S. sclerotiorum and other phytopathogens. In vitro and glasshouse trials revealed significant control of sclerotinia rot on lettuce plants. The optimal fermentation conditions for both strains were determined. The biocontrol mechanism of strain JH96 was attributed to reduction of oxalic acid secretion, whereas the biocontrol mechanism of strain JH92 was attributed to production of antifungal active compounds of glycitein and butyrolactone I. In particular, glycitein effectively inhibited the growth, sclerotia formation and sclerotium germination of S. sclerotiorum . CONCLUSION Results from this study clearly indicated that the two strains, in particular strain JH92, were antagonistic to S. sclerotiorum under in vitro and in vivo conditions. This revealed that both strains have great potential as environmentally‐friendly alternatives to chemical fungicides for biological control of Sclerotinia rot in lettuce production. © 2025 Society of Chemical Industry.