AUTHOR=Lim Soo-Hyun , Kim Harim , Noh Tae-Kyeong , Lim Ji-Soo , Yook Min-Jung , Kim Jin-Won , Yi Jee-Hwan , Kim Do-Soon 

TITLE=Baseline Sensitivity of Echinochloa crus-gall and E. oryzicola to Florpyrauxifen-Benzyl, a New Synthetic Auxin Herbicide, in Korea

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.656642

DOI=10.3389/fpls.2021.656642

ISSN=1664-462X

ABSTRACT=<p><italic>Echinochloa</italic> 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 <italic>Echinochloa</italic> management; however, the potential risk for the development of herbicide resistance in <italic>Echinochloa</italic> species has not been well-investigated. Thus, this study was conducted to evaluate the baseline sensitivity of <italic>Echinochloa</italic> species to florpyrauxifen-benzyl to estimate the risk of future resistance development. A total of 70 and 71 accessions of <italic>Echinochloa crus-galli</italic> and <italic>Echinochloa oryzicola</italic> were collected from paddy fields in Korea, respectively. These two <italic>Echinochloa</italic> 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<sup>–1</sup>. Nonlinear regression analyses revealed that GR<sub>50</sub> values for <italic>E. oryzicola</italic> ranged from 4.54 g to 29.66 g a.i. ha<sup>–1</sup>, giving a baseline sensitivity index (BSI) of 6.53, while those for <italic>E. crus-galli</italic> ranged from 6.15 g to 16.06 g a.i. ha<sup>–1</sup>, giving a BSI of 2.61. Our findings suggest that <italic>E. oryzicola</italic> has a greater potential risk than <italic>E. crus-galli</italic> for the development of metabolism-based resistance to florpyrauxifen-benzyl.</p>