Phytotoxicity of cacalol and some derivatives obtained from the roots ofPsacalium decompositum (A. Gray) H. Rob. & Brettell (Asteraceae), matarique or maturin.

The effect of cacalol and extracts (water and petroleum ether) derived from the roots ofPsacalium decompositum (Asteraceae) on the germination and radicle growth of two plants.Amaranthus hypochondriacus (Amaranthaceae) andEchinochloa crusgalli (Poaceae), and on the radial growth of four phytopathogenic fungi is described. The activity of two cacalol derivatives (methyl cacalol and cacalol acetate) was also investigated. Germination ofA. hypochondriacus was inhibited by almost all the treatments. The extracts and cacalol produced a significant inhibition of radicle growth ofA. hypochondriacus andE. crusgalli. Cacalol acetate showed a specific inhibition onE. crusgalli, and methyl cacalol significantly inhibited the growth ofA. hypochondriacus. In general, antifungal activity depended upon the target fungi and the concentration of each treatment. Cacalol had also effects on the morphology and coloration of the fungal mycelium. The bioactivity shown by the extracts ofPsacalium decompositum on the tested seeds and fungi is mainly due to their content in cacalol.