Antifungal Effects of Plant Extracts on Saffron Corms Infected with Three Pathogens

Background: Saffron corm rot causes significant yield losses worldwide. Although synthetic pesticides are commonly used for management, their overuse can lead to increased fungal resistance and pose a risk to public health. Numerous plants possessing antifungal properties hold significant potential for development as biocontrol agents against saffron corm rot. Result: In this study, the efficacy of biocontrol agents derived from natural plants was evaluated for managing saffron corm rot. Aqueous and 70% ethanol extracts from 15 plants were investigated for antifungal activity and virulence suppression against three saffron pathogens: Fusarium oxysporum, Penicillium citrinum, and Aspergillus brasiliensis. Antifungal activity experiments indicated that clove ethanol extract at a concentration of 20 mg/mL exhibited the highest inhibition rate, with values of 93.27 ± 0.0% for Fusarium oxysporum, 86.47 ± 5.55% for Penicillium citrinum, and 68.65 ± 2.40% for Aspergillus brasiliensis. Compared with the model group, clove ethanol extract significantly reduced corm rot and normalized the metabolism of infected corms. On day 30, compared with the model group (34.3 ± 3.7%), the rot rate of clove-treated corms was reduced to 17.2 ± 1.4%, and on day 60, it was reduced to 27.5 ± 1.5% (versus 52.9 ± 3.3% in the model group). Compared with the model group, the levels of soluble sugar, starch, α-amylase, soluble protein, and superoxide dismutase in clove-treated infected corms approached those observed in the control group. Field trials confirmed that clove ethanol extract effectively improved plant growth and reduced the disease severity index (37.00 ± 3.51) in infected corms. Conclusion: Clove ethanol extract is a promising candidate to replace or reduce the use of synthetic pesticides. It provides a theoretical and practical basis for the biocontrol of saffron corm rot.