Influence of Yellow Nutsedge (Cyperus esculentus)—Free Periods on Yield of Cotton (Gossypium hirsutum)

Yellow nutsedge (Cyperus esculentus L. # CYPES) was hoed in two cotton (Gossypium hirsutum L. ‘Acala SJ-2′) fields each year (1979 to 1981) for 2 to 12 weeks after crop emergence to evaluate the influence of several nutsedge-free periods on the growth and reproduction of nutsedge and yields of seed cotton. Compared to the control (plots cultivated but not hoed), a 2-week nutsedge-free period reduced the average number of nutsedge shoots at harvest by 52% (61 vs 29 shoots/m2). Additional hoeings for 4 to 12 weeks further reduced populations by 67 to 87%. Compared to tubers counted in the spring, populations of tubers in control plots increased 3- to 12-fold by harvest. However, compared to control plots, two weekly hoeings reduced tuber populations at harvest by 70 to 90% (treatment average of 884 vs 221 tubers/m2), and additional hoeings tended to reduce, or reduced, tuber populations further (75 to 98% reduction). When cotton yields were reduced in control plots in 1979 and 1980, a 2- to 6-week nutsedge-free period substantially decreased yield losses. Averaged over six locations, yields in plots with a 4- to 12-week nutsedge-free period were greater than yields of control plots.