In order to evaluate the effects of weed control and weed coexistence periods on cotton (Gossypium hirsutum) cultivar Delta Opal yield, an experiment was carried out consisting of two treatment groups. In the first, the crop was weed free from from emergence until 7, 14, 21, 28, 35, 42, 49, 56, 63 days, and harvest (159 days) respectively. In the second group, the crop was in competition with the weed community from emergence until the same period, as described for the first series of treatment, respectively. Among the weed species found in the experimental area, the most important were purple nutsedge (Cyperus rotundus), sicklepod (Senna obtusifolia), indigo (Indigofera hirsuta) and sandbur (Cenchrus echinatus). The period after cotton plant emergence and previous to weed interference, which reduced cotton yield in 5% was 8 days (DAE); the Total Period of Interference Prevention (TPIP) was 66 DAE and the Critical Period of Interference Prevention (CPIP) was between 8 to 66 DAE.
coexistence period; weed competition
