Weed control, corn safety, and mechanism of the novel herbicide HW-3

Context HW-3 acts as a pyruvate dehydrogenase herbicide for weed control. However, its biological efficacy against weeds, as well as its safety concerning gramineous crops, remains poorly understood. Aims The objectives of this study were to determine the efficacy of HW-3 against common weeds in corn fields and identify the safety of HW-3 on different cultivars and leaf stages of corn. Methods This study determined the toxicity of HW-3 to common weeds in cornfields under greenhouse conditions through whole plant bioassay. The study also determined the mechanism of action and selectivity principle of HW-3 through in vitro enzyme activity measurements. Key results When HW-3 was applied at 150 g of active ingredient ha−1, the fresh weight inhibition rates of the broad-leaved weeds Eclipta prostrata, Ludwigia prostrata, Ammannia baccifera, Ammannia auriculata, Amaranthus retroflexus, Portulaca oleracea, Abutilon theophrasti, and Cyperus rotundus in the corn field were all above 90%. The selectivity indices of HW-3 in common corn, sweet corn, and glutinous corn were 4.29, 4.22, and 4.98, respectively, indicating the safety of HW-3 across different corn types. The concentration causing 50% inhibition (IC50 value) of pyruvate dehydrogenase activity in A. theophrasti treated with HW-3 was 287.94 mg L−1, and the IC50 value of PDH activity in corn was much greater than 1000 mg L−1. This indicates that HW-3 is a selective pyruvate dehydrogenase inhibitor. Conclusions HW-3 has potential use for the control of broad-leaved weeds in cornfields and is safe for different types and leaf stages of corn. Implications This research provides a reference for the commercial application of HW-3.