POPULATION-DYNAMICS OF YELLOW NUTSEDGE (CYPERUS-ESCULENTUS) IN CROPPING SYSTEMS IN THE SOUTHEASTERN COASTAL-PLAIN

Studies were conducted from 1990 through 1994 near Tifton, GA, on the population dynamics of yellow nutsedge and certain annual weeds in pea nut-corn and peanut-cotton rotations. Converse rotation sequences were included to eliminate year effects. Continuous fallow plots (noncrop) were included for comparison. Within each crop, including fallow, wer e 3 levels of weed management: low, moderate, and intensive. Weed dens ities and numbers of yellow nutsedge tubers were not affected by crop rotations, but they were affected by individual crops and weed managem ent systems in each crop. Fallow plots, including those with intensive fallow weed management using tillage and nonselective herbicides, con sistently contained more yellow nutsedge plants and tubers than other plots. Moderate and intensive weed control systems in peanut and cotto n reduced yellow nutsedge densities and tubers, but only peanut yields were increased by intensive weed management. Weed management systems did not affect yellow nutsedge densities in corn, although yields were increased by moderate and intensive systems due to improved control o f other weeds. Our results suggest that uninterrupted plantings of pea nut, corn, or cotton with moderate levels of weed management are gener ally sufficient to suppress yellow nutsedge and allow for optimum crop yield. If fields are fallow, yellow nutsedge population densities and tubers will increase exponentially, even with intensive fallow weed m anagement.