Effect of MON 12037 on the growth and tuber viability of purple nutsedge (Cyperus rotundus)

A field study was conducted in 1994 and 1995 to determine the efficacy of MON 12037 on purple nutsedge in a bermudagrass turf. The percentage of bermudagrass infested with purple nutsedge following a single application of MON 12037 decreased from 60 to 30% at 18 g ai/ha and to approximately 20% at 36, 54, and 72 g/ha. Regrowth of purple nutsedge occurred between 28 and 55 d after treatment (DAT) and was greatest at 18 g/ha. A second application of MON 12037 reduced purple nutsedge percent infestation similarly to one application. Tuber weight and number were not affected by either one or two applications of MON 12037; however, tuber viability decreased after two applications. These results suggest that when using MON 12037, a program of several years duration may be required to successfully manage purple nutsedge in a bermudagrass turf because viable tubers persist following two applications of MON 12037 in a season.