The antifungal effects of some plant extracts on Sclerotium rolfsii, the causal agent of peanut white stem rot disease

Secondary metabolites of plants are used to protect plants against fungal and bacterial diseases. This research evaluated the effect of 10 plant extracts prepared with either ethanol solvent or methanol solvent on the control of Sclerotium rolfsii, the causal agent of peanut white stem rot disease, under in vitro and greenhouse conditions. The plant extracts were extracted from Trachyspermum copticum, Ocimum basilicum, Eugenia caryophillata, Eucalyptus camaldulensis, Thymus pubescens, Mentha aquatical, Urtica dioica, Rosmarinus officinalis, Artemisia dracunculus, and Viola odorata. The in vitro trials were conducted on both the ethanolic and methanolic extracts at different rates of 0, 0.5, 0.75, 0.125, and 1.0 in a factorial experiment based on a completely randomized design in three replications. The greenhouse trials examined the effects of 10 net plant extracts on the morphological traits and peanut crown infection percentage. According to the in vitro trials, the highest inhibitory activity was observed in the ethanolic and methanolic extracts of E. caryophillata so that it fully inhibited the mycelial growth of the pathogen irrespective of its rate. In the greenhouse trials, E. camaldulensis among the ethanolic extracts and R. officinalis among the methanolic extracts were most effective in reducing disease severity. All studied plant extracts improved the vegetative traits of the peanuts. Based on the results, the extracts of E. caryophillata, E. camaldulensis, and R. officinalis can be used to biologically control peanut white stem rot disease. How plant extracts act has practical relevance for suppressing pathogenic fungi because they can provide useful information for preparing appropriate specific formulations.