Management, Ecology, and Genetics of Yellow Nutsedge (Cyperus esculentus L.) in Turfgrass

Yellow nutsedge (Cyperus esculentus L.) is one of the most widely distributed and troublesome weeds in the world. Chemical control of yellow nutsedge is often inconsistent. Field and greenhouse studies were conducted to optimize strategies for increased yellow nutsedge control with halosulfuron and sulfentrazone. Both herbicides reduced yellow nutsedge ground cover from 70–99%, root and rhizome dry mass from 39–98%, tuber formation and average tuber fresh weight from 38–100%, and can prevent re-emergence. Herbicide applications should be made as early as possible postemergence, preferably at the three- to five-leaf stage. Halosulfuron was more effective in suppressing yellow nutsedge within a mixed turfgrass stand, whereas sulfentrazone was more effective when turfgrass was absent. Sequential applications of either herbicide within a three-week interval is recommended for optimal control. An ecology study was conducted to evaluate interference between Kentucky bluegrass (Poa pratensis L.) and yellow nutsedge in a home lawn setting. Yellow nutsedge was germinated from a single parent tuber, either within Kentucky bluegrass, or in bare soil. Plots were not irrigated, irrigated with 80% ET replacement, or irrigated 167 L plot–1 wk–1, and fertilized with 0, 97, or 195 kg N ha–1 year–1. Yellow nutsedge shoot and tuber production were slowest in non-irrigated and non-fertilized plots. Managers should consider using deficit-based irrigation in yellow nutsedge infested turfgrass instead of 80% ET replacement or irrigating without considering precipitation. Fertility recommendations should be based on expectations of turfgrass quality, avoiding excessive fertilizer applications in yellow nutsedge infested turfgrass. The presence of actively growing Kentucky bluegrass impedes tuber and shoot production of yellow nutsedge from 65 to 99%, proving that maintenance of an actively growing Kentucky bluegrass stand is a powerful cultural practice to reduce the invasiveness of yellow nutsedge. Amplified fragment length polymorphism (AFLP) was used to compare clones collected from a local golf course in Lincoln, NE with those collected in Nebraska, Kansas, Minnesota, Indiana, and cultivated chufa. Results indicated a low level of genetic variability among samples collected within populations, whereas a higher level of variability was found among distinct populations