The alelopathic potential of cucumber (Cucumis saitvus L.) plants after their crop harvest was investigated. Aqueous methanol extracts inhibited the growth of shoots of cress (Lepidium sativum L.) alfalfa (Medicago sativa L) and barnyardgrass (Echinochloa crus-galli (L.) Beauv). A potent growth inhibitory subsance in the extract was isolated by chromatographic separation of silica gel and Sephadex columns, Sep-Pack cartridge and HPLC. Full article