Rates of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) applied preplanting were combined with rates of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] applied postemergence in cotton (Gossypium hirsutum L. ‘Deltapine 16’). In another experiment, two levels of these herbicides were applied in three populations of cotton. All herbicide combinations improved weed control, compared to that of cultivated checks. Applications of 0.28, 0.42, and 0.56 kg/ha of trifluralin combined with 0.56 kg/ha of diuron controlled annual weeds and produced the highest cotton yields. Herbicide treatments had more influence than crop spacing on weed control and crop yield. Weed competition on cultivated checks affected boll weight, seed per boll, and fiber fineness.