The volatile compounds act as fungistatic or fungicidal components that disrupt fungal cell metabolism due to the oxidation of proteins (Baron & Tansey, 1977; Slusarenko et al., 2008). Allicin is readily membrane-permeable and undergoes thiol-disulphide exchange reactions with free thiol groups in proteins. It is thought that these properties are the basis of its antimicrobial action. Alan et al., (2008) reported that the reduction in disease was apparently due to a direct action against the pathogen since no accumulation of salicylic acid (a marker for systemic acquired resistance, SAR) was observed after treatment with garlic bulb crude extract in downy mildew of Arabidopsis. We see a potential for developing preparations from garlic for use in organic farming, e.g., for reducing the pathogen inoculum potential in planting material such as bulbs, seeds and tubers.