Control of Yellow and Purple Nutsedge in Bermudagrass with V-10142.

Chemical control of yellow nutsedge (Cyperus esculentus L.) and purple nutsedge (Cyperus rotundus L.) is difficult due to the presence of persistent underground tubers. Several herbicides are labeled for the control of both species, but long-term control is still difficult to achieve. V-10142, an experimental herbicide from Valent Corp., has shown potential to control both yellow and purple nutsedge. Experiments were conducted in the summer of 2007 at Abilene Country Club in Abilene, TX. Treatments were applied to established infestations of yellow and purple nutsedge in a common bermudagrass (Cynodon dactylon (L.) Pers.) rough grown on sandy loam soil. The experimental design was a randomized complete block with four replications. Treatments were initiated on July 10, 2007 and included an untreated check, V-10142 at 0.56 kg ai/ha followed by (fb) V-10142 at 0.56 kg ai/ha at various timing intervals, V-10142 at 1.12 kg ai/ha, and trifloxysulfuron at 0.03 kg ai/ha. Each plot was assessed at the time of initial herbicide application for percent cover of yellow or purple nutsedge. Percent cover and visual bermudagrass injury ratings were evaluated at 1, 2, 3, 4, 6, 8, and 12 weeks after initial treatment (WAIT). No bermudagrass phytotoxicity was recorded throughout the length of either study. All treatments provided 100% control of yellow nutsedge 12 WAIT except V-10142 fb V-10142 1 WAIT (90%). Among the four sequential treatments, V-10142 fb V-10142 3 WAIT provided the highest control (91%) of purple nutsedge 12 WAIT. V-10142 fb V-10142 2 or 4 WAIT provided 82% control 12 WAIT, while trifloxysulfuron provided 80% control 12 WAIT. Purple nutsedge control with V-10142 at 1.12 kg ai/ha and V-10142 fb V-10142 1 WAIT was only 71 and 42%, respectively, 12 WAIT.