This study was conducted to assess the population dynamics of two major weeds of the family Poaceae associated with a banana agroecosystem. The experiment was conducted in the area of Cariari de Pococí between October 2003 to September 2005. An experiment with four weed control treatments was established as a randomized blocks design. The treatments were: bimonthly mechanical control with machete, scheduled applications of glyphosate, scheduled applications of gluphosinate, and a treatment based on the monitoring of the weed population. The main Poaceae registered were Panicum polygonatum and Axonopus micay. Weeds were counted every two months. The second evaluation showed that glyphosate tended to reduce significantly the populationsof P. polygonatum, while mechanical control favored the development of this species; gluphosinate applicationsresulted in intermediate populations of the weed. Gluphosinate treatments and mechanical control resulted in higher populations of A. micay.
Keywords: P. polygonatum, A. micay, glyphosate, gluphosinate ammonium, mechanical control.