Antifungal activity of garlic essential oil and hydrosol against Zymoseptoria tritici, the causal agent of septoria tritici blotch in bread wheat
Septoria tritici blotch (STB), caused by Zymoseptoria tritici, is one of the most damaging foliar diseases of bread wheat (Triticum aestivum L.), leading to yield losses of up to 50% under favorable conditions and increasing reliance on synthetic fungicides. In this study, the antifungal activity of essential oil (EO) and hydrosol (the aqueous phase obtained as a by-product of hydrodistillation) derived from a local Algerian red garlic variety was evaluated in vitro against Z. tritici. Garlic extracts were characterized through morphological, physicochemical, and chemical analyses, with the volatile composition of EO determined by gas chromatography–mass spectrometry (GC–MS). The EO was rich in organosulfur compounds, particularly diallyl trisulfide and diallyl disulfide. Antifungal assays demonstrated a strong dose-dependent inhibition of mycelial growth, as evaluated by radial growth inhibition percentage. Garlic essential oil completely inhibited fungal growth at 0.30 µL mL⁻¹, although a reduction in efficacy over time suggested limited stability. Notably, garlic hydrosol achieved complete and stable inhibition at 150 µL mL⁻¹, representing a promising and underexplored approach for STB control.