Coffee Senna (Cassia occidentalis) Competition with Cotton (Gossypium hirsutum)

Field research was conducted at two locations in 1982 and 1983 to evaluate the competitiveness of coffee senna (Cassia occidentalisL. # CASOC) with cotton (Gossypium hirsutumL.). With season-long competition, each increase of 1 coffee senna plant/7.5 m of row reduced seed cotton by 9 to 117 kg/ha. Each additional week of competition from a dense stand (40 plants/m of row) of coffee senna reduced seed cotton yield by 118 kg/ha and cotton main stem height by 1.25 cm. Neither cotton stand density nor fiber properties were affected by coffee senna density or duration of competition. Seed cotton yields and main stem heights obtained when cotton was kept weed free for 6 weeks after cotton emergence were not significantly different from those kept weed free for 8, 10, or 14 weeks. Coffee senna dry-matter production was essentially zero when cotton was maintained weed free for 8 or more weeks.