Postemergence Control of Carolina Dichondra in Hybrid Bermudagrass.

Field experiments were conducted in Athens, GA during the summer of 2016 on ‘TifTuf’ hybrid bermudagrass (5.1 cm) with a mature infestation of Carolina dichondra. Plots measuring 1.5 x 1.5 m were arranged in a randomized complete block with four replications. Herbicide treatments were initiated on July 12, 2016 with a sequential application made on August 17, 2016. Treatments consisted of EH1587 (halauxifen-methyl + fluroxypyr + dicamba) at 0.31 kg ai ha^-1, EH1580 (penoxsulam + pyrimisulfan – fertilizer carrier) at 0.09 kg ai ha^-1, Surge (sulfentrazone + 2,4-D + MCPP + dicamba) at 0.99 kg ai ha^-1, 4-Speed XT (2,4-D + triclopyr + dicamba + pyraflufen) at 1.4 kg ai ha^-1, Celsius (thiencarbazone + iodosulfuron + dicamba) at 0.18 kg ai ha^-1, Triplet (2,4-D + MCPP + dicamba) at 1.58 kg ai ha^-1, and Negate (rimsulfuron + metsulfuron) at 0.04 kg ai ha^-1. An untreated check was included for comparison. Herbicides were applied with a CO₂ powered backpack sprayer calibrated to deliver 187 L ha^-1 at 241 kPa. Visual ratings of % Carolina dichondra control were recorded at 2, 5, and 10 weeks after initial treatment (WAIT). Plots averaged approximately 60% Carolina dichondra cover at the trial start. Initial Carolina dichondra control (2 WAIT) was greatest in response to 4-Speed XT (83%), Triplet (78%), and Surge (72%). All other treatments resulted in ≤ 33% control 2 WAIT. Triplet, 4-Speed XT, Surge, and Celsius applications resulted in 96% to 100% Carolina dichondra control 5 WAIT. Control in response to EH1587 and EH1580 was 71% and 58%, respectively, while control with Negate was only 24% 5 WAIT. Surge, Triplet, 4-Speed XT, and Celsius maintained excellent control (96% to 100%) 10 WAIT. Control with EH1587 and EH1580 increased to 82% and 72%, respectively, while control with Negate was reduced to 19% 10 WAIT.