The competitive effect ofOxalis latifoliaH.B.K, (red garden sorrel) in maize has been investigated in the past four seasons at Cedara. The site chosen had a heavyO. latifoliainfestation. In each of the four seasons initial weed control was achieved on all plots using a mixture of atrazine, terbuthylazine and metolachlor. This treatment controlled a wide spectrum of weeds exceptO. latifoliawhich became the dominant species present. On ten plots this weed was allowed to compete with maize throughout the season. This was compared with another ten maize plots where most of theO. latifoliawas selectively controlled. Maize grain yields, plant lodging counts and the incidence ofDiplodiaandFusariumcob rots were not significantly altered by up to 329 well-developedO. latifoliaplants m−2compared with up to 55 insignificant plants m−2in the control plots.