Weed Competition in Cotton. I. Sicklepod and Tall Morningglory

Abstract

Cotton (Gossypium hirsutumL.) was grown at two locations in Alabama during 1966 to 1969 with specific densities of sicklepod (Cassia obtusifoliaL.) and tall morningglory (Ipomoea purpureaL. Roth). Competition from sicklepod and tall morningglory caused cotton yield reductions at densities as low as eight weeds per 7.31 m of row. Tall morningglory was usually more competitive than sicklepod in cotton. Both species were more competitive on Lucedale sandy clay loam than on Norfolk sandy loam. Sicklepod at eight weeds per 7.31 m of row reduced yields from 10 to 23% on the Norfolk soil and approximately 40% on the Lucedale soil. At the highest density, 48 sicklepod plants per 7.31 m of row, yields were reduced 45 to 65% on the Norfolk soil and approximately 80% on the Lucedale soil. Tall morningglory at a density of eight weeds per 7.31 m of row reduced cotton yields 10 to 40% on the Norfolk soil and 50 to 75% on the Lucedale soil. Vegetative growth, boll, and seed size were not affected as much as cotton yields by competition. Percentage lint and lint fiber properties were unaffected by competition.