LAUSR

Abstract A novel 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide, 4-(2-chloro-4-(methylsulfonyl)-3-((2,2,2- trifluoroethoxy) methyl) benzoyl)-1-ethyl-1H-pyrazol-5-yl 1,3-dimethyl-1H- pyrazole-4-carboxylate (QYC101), was evaluated under greenhouse and field conditions in China to determine its efficacy against weeds and safety towards maize via post-emergence (POST) applications. In the greenhouse experiment, QYC101 application at 15 g a.i. ha−1 was highly effective (>80% dry weight reduction) at controlling some major weed species present in maize production systems in China such as Solanum nigrum L., Amaranthus retroflexus L., Digitaria ischaemum (Schreb.) Schreb. ex Muhl., Setaria glauca (L.) Beauv., Setaria viridis (L.) P. Beauv. and Eleusine indica (L.) Gaertn. The tolerance results revealed that 22 of the tested maize hybrids displayed different levels of tolerance to QYC101 application at 90 and 180 g a.i. ha−1. The results obtained from the field experiments in 2016 and 2017 showed that QYC101 applications at 45, 67.5, 90 and 135 g a.i. ha−1 provided an 88.7–97.4% weed biomass reduction and a 10.1–22.2% yield increase in maize fields. These results indicate that QYC101 has great potential for weed management in maize production systems in China.