Sequential Postemergence Applications for the Control of Khakiweed in Bermudagrass.

Field experiments were conducted at Meadowbrook Country Club in Lubbock, TX in 2010 to examine the efficacy of postemergence herbicides for the control of khakiweed. Studies were located on established infestations of khakiweed present in a common bermudagrass rough. Plots measured 1.5 m² and were arranged in a randomized complete block design with four replications. Treatments were applied using a CO₂ backpack sprayer equipped with XR8004VS nozzles calibrated to deliver 375 L/ha at 221 kPa. Treatments were initiated on June 11, 2010 and consisted of metsulfuron (0.036 or 0.072 kg ai/ha), trifloxysulfuron (0.019 or 0.028 kg ai/ha), carfentrazone + 2,4-D + mecoprop + dicamba (0.45 kg ai/ha), 2,4-D + triclopyr + dicamba + pyraflufen (1.2 kg ai/ha), aminocyclopyrachlor (52.6 g ai/ha), pendimethalin (2.2 kg ai/ha) + [quinclorac + mecoprop + dicamba (0.69 kg ae/ha)], pendimethalin (2.2 kg ai/ha) + BAS 8004H (3.5 g ai/ha), pendimethalin (2.2 kg ai/ha) + quinclorac (0.42 kg ae/ha), and thiencarbazone + iodosulfuron + dicamba (176.5 g ai/ha). Sequential applications were made 3 to 5 weeks after initial treatment (WAIT). Visual estimates of % khakiweed control were taken 1, 2, 4, 6, and 8 WAIT. Data were subjected to analysis of variance (ANOVA) and means were separated using Fisher’s Protected LSD at (α = 0.5). Thiencarbazone + iodosulfuron + dicamba, 2,4-D + triclopyr + dicamba + pyraflufen, pendimethalin + BAS 8004H, and metsulfuron treatments exhibited ≥ 92% control 4 WAIT. All other treatments exhibited ≤ 70% control 4 WAIT. Thiencarbazone + iodosulfuron + dicamba, 2,4-D + triclopyr + dicamba + pyraflufen, pendimethalin + BAS 8004H, metsulfuron,  pendimethalin  + quinclorac + mecoprop + dicamba, pendimethalin  + quinclorac, and aminocyclopyrachlor exhibited ≥ 92% control 8 WAIT. Trifloxysulfuron treatments exhibited 81 to 87% control, while control with carfentrazone + 2,4-D + mecoprop + dicamba decreased to 30% 8 WAIT.