Kleigrass pastures: Effects of infestation by purple nutsedge.

Investigations were conducted in the La Pampa province, Argentina, to study allelopathic potential of purple nutsedge or nutgrass (Cyperus rotundus) on germination and survival of seeds and seedlings of kleingrass (Panicum coloratum). Results of laboratory experiments using extracts from roots, bulbs and leaves of C. rotundus are summarised. A diagram is included on effect of root, bulb and leaf extracts on survival of grass seedlings. Evidence was obtained that the extract from bulbs had the highest allelopathic effect. The weed is characterized by a high ability for regeneration year after year after the rest period in the bulb state. It is recommended to reduce quantities and sizes of bulbs and roots of the weed as a measure to prevent reinfestation.