Bermudagrass Tolerance of the Herbicide Sethoxydim.

Sethoxydim, an acetyl-CoA carboxylase (ACCase) inhibiting herbicide, is typically used to control grass weeds in broadleaf crops. The development of a sethoxydim tolerant turfgrass would give managers a new chemical tool for use on troublesome grass weeds such as crabgrass (Digitaria spp.) and goosegrass (Eleusine indica). A non-genetically engineered sethoxydim tolerant bermudagrass (Cynodon dactylon), 93-175, previously developed by the turfgrass breeding program at the University of Georgia Tifton Campus was used as a parent to develop a new population of 56 hybrids during 2016. The tolerance of these genotypes to sethoxydim injury when applied at a labeled rate of 1.75 L Ha^-1 was estimated during the spring of 2017 using a visual scale of 1-9, fresh tissue weight of clippings from cone-tainers maintained at 3cm height of cut, and the corresponding weights after drying at 15.5 °C for 2 wks. Correlation of turf quality to fresh clipping weight and turf quality to dry clipping weight 68 DATwas 0.80 and 0.79, respectively. The four experimental hybrids that had less injury than 93-175 at 28 DAT, after sethoxydim application will be evaluated for response to rates of sethoxydim, clethodim, fluazifop, quizalofop, and fenoxaprop in efforts to characterize the level of inherited herbicide tolerance in the most sethoxydim tolerant hybrid lines. The remaining 52 bermudagrass hybrids that performed similarly or worse than Tifway and Celebration will not be further evaluated at this time.