Influence of Cotton (Gossypium hirsutum) Densities on Competitiveness of Pigweed (Amaranthusspp.) and Sicklepod (Cassia obtusifolia)

Experiments were conducted from 1973 through 1975 on Lucedale sandy loam to determine the influence of in-row cotton (Gossypium hirsutumL. ‘Stoneville 213’) densities on the competitiveness of low-level infestations of sicklepod (Cassia obtusifoliaL.) and pigweed (Amaranthusspp.). Weeds were established at densities of 0, 4, 12, and 32 weeds per 15 m of row and allowed to compete the entire season with cotton grown at densities of 5, 10, or 20 plants/m of row corresponding to 47000, 94000 and 187000 cotton plants/ha. Conventional cultural practices were employed in these experiments. Cotton yields were inversely related to weed density; however, the density of cotton did not influence the competitive effect of sicklepod or pigweed. Pigweed or sicklepod dry weed weight was reduced when competing with 187000 cotton plants/ha.