Abstract

In vitro studies were carried out to investigate the inhibitory effect of allicin in garlic juice on hyphal growth and spore germination of Drechslera tritici-repetis, Bipolaris sorokiniana andSeptoria tritici. The purpose was to investigate the possibility of developing an organic agriculture compatible garlic/allicin-based management strategy for the wheat fungal spotting complex. Allicin in garlic juice inhibited radial colony growth of all three pathogens on agar plates. Spore germination of all three pathogens was inhibited by allicin in garlic juice in seeded agar plates and in conidial suspensions. At high concentrations of allicin (> 80 µg/ml) in garlic juice and pure (synthetic) allicin, conidia lysed. The minimum inhibitory amount of pure synthetic allicin which inhibited spore germination completely ranged between 80 to 120 µg/ml, depending on fungal species. At 10 µg/ml, allicin caused morphological abnormalities in hyphae and conidia of D. tritici-repentis and B. sorokiniana. The current work also provides novel information regarding the effect of allicin-treated hyphae that were collapsed, damaged or thinner when compared with the control. These results suggest that the use of garlic juice is a promising, effective and environmentally friendly management measure against fungal pathogens that could be used in the production of an organically grown wheat crop.

Key words: Antifungal activity, growth inhibition, wheat, plant pathogens, allicin, garlic extract.