Response of JSC 2‐21‐18 (Iron Cutter ^® ) hybrid bermudagrass to postemergence herbicides and plant growth regulators

Abstract A field study was conducted in Athens, GA, to evaluate JSC 2‐21‐18 (Iron Cutter ® ) hybrid bermudagrass ( Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy) response to postemergence herbicides (topramezone + metribuzin, thiencarbazone‐methyl + foramsulfuron + halosulfuron, thiencarbazone‐methyl + iodosulfuron + dicamba, 2,4‐D + triclopyr + dicamba + pyraflufen, foramsulfuron, sulfosulfuron, monosodium methanearsonate, quinclorac, and 2,4‐D + mecoprop + dicamba + carfentrazone). Thiencarbazone‐methyl + foramsulfuron + halosulfuron, thiencarbazone‐methyl + iodosulfuron + dicamba, monosodium methanearsonate, and 2,4‐D + mecoprop + dicamba + carfentrazone resulted in similar turfgrass color (TC), turfgrass quality (TQ), and normalized difference vegetation index (NDVI) as the non‐treated check, regardless of rating date. Topramezone + metribuzin and 2,4‐D + triclopyr + dicamba + pyraflufen were most injurious, causing significantly lower TC, TQ, and NDVI than the non‐treated check 3 weeks after treatment (WAT). Decreases in TC were also observed in response to quinclorac, sulfosulfuron, and foramsulfuron 3 WAT; however, recovery from quinclorac and sulfosulfuron was reported 4 WAT. A second study examined JSC 2‐21‐18 response to trinexapac‐ethyl (TE), prohexadione calcium (PC), and TE + PC applied every 2 weeks. All treatments resulted in higher TC, TQ, and NDVI than the non‐treated check 40 days after initial treatment (DAIT), except TE at 96 g ai ha −1 with respect to TQ. The highest TC, TQ, and NDVI was observed in response to PC at 460 g ai ha −1 . At 84 DAIT, TE + PC resulted in the greatest percent growth inhibition (GI) (46%) followed by PC (41%), regardless of rate, while TE only resulted in % GI of 31%–32%. In general, a greater increase in aesthetics and inhibition was observed in response to PC than TE.