Constituent content and allelopathic potential of eighteen extracts for the control of Urochloa decumbens under laboratory conditions

•Medicinal plants can show allelopathic potential.•Plant extracts rich in phenols, flavonoids and tannins showed high allelopathic activities.•Annona dioica (Annonaceae), Stryphnodendron adstringens (Fabaceae) and Palicourea crocea (Rubiaceae) decelerated U. decumbens seed germination.•Alternative methods for controlling U. decumbens in areas of ecological restoration.