Evaluation of different plant aqueous extracts for effective management of Thielaviopsis paradoxa causal agent of the black scorch disease in date palm fronds in Morocco

Date palm plays an essential role in the Moroccan economy today. However, the plantations are vulnerable to contamination by fungi such as Thielaviopsis paradoxa, a pathogen that causes black scorch disease. The objectives of present investigation are to report the antifungal efficacy of aqueous extracts from five species—Eucalyptus globulus, Olea europaea, Euonymus japonicus, Nerium oleander, and Ficus microcarpa —against T. paradoxa, tested for spore germination inhibition and radial growth inhibition. Additionally, this study aims to identify the richness of these extracts in polyphenols and flavonoids and to evaluate their antioxidant properties. The extracts of these plants showed significant differences in their antifungal activity (p < 0.01). Notably, this study revealed that the aqueous extract of E. globulus at 8% exhibits strong antifungal activity, inhibiting spore germination by 76.15% and reducing radial growth by 96.15%. The efficacy of this extract is comparable to that of Chlorothalonil (2 g/L) and surpasses that of Fosetyl-aluminium (2.5 g/L). Correlation analysis demonstrated a relationship between phenolic compound content and both antioxidant along with antifungal activities, suggesting that these bioactive polyphenol compounds play a significant role in the observed effects.