A composition having a germination-preventing activity, comprising, as active principle, allyl isothiocyanate alone or in combination with other substances having a synergic action, in the form of emulsifiable formulates or as a microencapsulate in which allyl isothiocyanate is englobed in a polymeric-based system for the controlled release of the active principle. The microcapsule membrane represents a weight percentage of 5-25%, the surfactant 2-10% and allyl isothiocyanate a weight percentage not lower than 70%.
