In vitro antifungal activity of garlic (Allium sativum L.) volatile compounds against Bipolaris sorokiniana, the causal agent of barley spot blotch

Spot blotch is an important seed-borne foliar disease of barley ( Hordeum vulgare L.) caused by Bipolaris sorokiniana (Sacc.) Shoemaker, which can lead to considerable yield losses and deterioration of grain quality. The present study assessed the in vitro antifungal activity of garlic ( Allium sativum L.) volatile compounds as a potential eco-friendly alternative to synthetic fungicides. The pathogen was isolated from infected barley seeds (cv. Fouara) and evaluated on potato dextrose agar (PDA) using a sealed-vial assay in which sterilized garlic bulbs (slightly wounded to release volatiles) were fixed to the inner side of the vial cap above a 5-mm mycelial plug. Mycelial growth was recorded daily for 11 days at 20 °C under continuous light. Garlic volatiles resulted in complete inhibition of fungal growth (100% inhibition) throughout the incubation period, while the control showed normal colony expansion. These findings indicate that garlic-emitted volatiles have strong antifungal potential against B. sorokiniana and could be further investigated under greenhouse and field conditions as part of integrated spot blotch management.