A trial was conducted at the Centro de Investigaciones y Asesorias Agroindustriales (CIAA) of the Universidad Jorge Tadeo Lozano, Chia (Cundinamarca) under greenhouse conditions to assess the effect of incorporating fresh above-ground material of seven plant species (Tagetes zipaquirensis, T. erecta, Brassica cempestris. Bidens pilosa, Rufa graveolens, Taraxacum officinale and Ricinus communis) on the yield and commercial quality of a carrot (Daucus carota) crop var. Mokum, on the population density of Meloidogyne hapla and on the intensity of root-knotting of carrot. No significant differences were detected in the biological yield of carrot plants, but commercial average production obtained from plots.treated with R. graveolens and T. officinale were the highest (3070 g.m·2 and 2270 g.m·2) and significantly different from the control plots (1090 g.m·2). Final average population densities of infective secondstage juveniles [J2] of M. hapla were significantly lower in the plots treated with R. communis, T. officinale, B. campes tris and T. erecta (65-130 Jj100 g of soil) than in the control plots (435 J2/100 g of soil). Significant differences were detected between rootknotting intensity of control plots (5.0 knots per root tip) and the averages of other treaments (1.9-2.6 knots per root tip).