Abstract:The allelopathic effects of aqueous extract, root exudates, shoot leachates and decomposition from C. canadesis on radish (Raphanus sativus L.), cucumber (Cucumis sativus L.), crabgrass (Digitaria sanguinalis (L.) Scop.), rape (Brassica campestris L.) and wheat (Triticum aestivum L.),were tested in petri dishes in laboratory. and the shoot leachates and root exudates were also tested in pot in greenhouse. The aqueous extract strongly inhibited the seedling growth of the tested plants. The root exudates, shoot leachates and decomposition inhibited the seedling growth of the tested plants differently, and the inhibitory effect of the root exudates was highest, The similar results were gotten from the greenhouse test. C. canadesis released the allelochemicals mainly through root exudates.