Biological control of Parthenium. I: Effect of Imperata cylindrica on distribution, germination and seedling growth of Parthenium hysterophorus L.

Natural products have been the source of many pesticides, used either directly as crude preparations or as pure compounds. The present study was undertaken evaluate prospects of control of P. hysterophorus by using crude preparations of Imperata cylindrica (L). Beauv., an allelopathic grass. Ecological survey revealed that frequency and density of P. hysterophorus was significantly lower in I. cylindrica dominating localities as compared to nearby areas without I. cylindrica infestation. Aqueous extracts of I. cylindrica exhibited the potential to control germination and seedling growth of P. hysterophorus Aqueous root and shoot extracts of 5, 10, 15, 20 and 25% (w/v) concentration were employed against germination and seedling growth of P. hysterophorus. Root and shoot aqueous extracts of all the applied concentrations significantly suppressed the germination of P. hysterophorus. Early seedling growth of P. hysterophorus was generally reduced significantly by extracts of 10% and of higher concentrations. Increasing the concentration of the extract increased the inhibitory potential. Shoot extract was more inhibitory than root extract.