Baseline Sensitivity of and to Florpyrauxifen-Benzyl, a New Synthetic Auxin Herbicide, in Korea.

species is one of the most problematic weed species due to its high competitiveness and increasing herbicide resistance. Florpyrauxifen-benzyl, a new auxin herbicide, was recently introduced for management; however, the potential risk for the development of herbicide resistance in species has not been well-investigated. Thus, this study was conducted to evaluate the baseline sensitivity of species to florpyrauxifen-benzyl to estimate the risk of future resistance development. A total of 70 and 71 accessions of and were collected from paddy fields in Korea, respectively. These two species were grown in plastic pots up to the 5-leaf stage, and treated with florpyrauxifen-benzyl at a range of doses from 2.2 g to 70.0 g a.i. ha. Nonlinear regression analyses revealed that GR values for ranged from 4.54 g to 29.66 g a.i. ha, giving a baseline sensitivity index (BSI) of 6.53, while those for ranged from 6.15 g to 16.06 g a.i. ha, giving a BSI of 2.61. Our findings suggest that has a greater potential risk than for the development of metabolism-based resistance to florpyrauxifen-benzyl.