Paraquat was the most successful nonselective herbicide in Korea due to its rapid herbicidal activity. However, its high mammalian toxicity, frequent self-poisoning incidents, and a lack of effective antidotes led to a paraquat ban in Korea in 2012. Therefore, this review was conducted to revisit the toxicological profile of paraquat and to investigate the impacts of the paraquat ban on human health and agriculture in Korea. A review of toxicological information reconfirmed that paraquat is highly acutely toxic to humans, and ingestion, inhalation, or dermal administration of the herbicide can cause severe clinical signs and inevitably lead to death by respiratory failure. In Korea, the paraquat ban immediately decreased the suicide rate due to pesticides (mainly paraquat) by 46.1%, resulting in a 10% decrease of the total suicide rate. However, this also led to an increase in suicide attempts with other poisons such as carbon monoxide, suggesting that suicide attempts and rates of suicide by poisoning depend on not only the toxicity of the poison but also the accessibility of the poisoning agents. In agriculture, paraquat was quickly replaced by other nonselective herbicides such as glufosinate and glyphosate. Thus, the paraquat ban did not have a significant impact on agricultural practices but influenced the nonselective herbicide market; the use of glufosinate was higher than use of glyphosate due to glufosinate’s rapid herbicidal activity, which is similar to that of paraquat. Though the paraquat ban can be considered as a national strategy to lower suicide rates, the increase in suicide attempts with other poisons suggests that multilateral efforts are required for not only keeping suicidal agents away from people but also minimizing motives for suicide.

Echinochloa is a major weed that grows almost everywhere in farmed land. This high prevalence results from its high adaptability to various water conditions, including upland and paddy fields, and its ability to grow in a wide range of climates, ranging from tropical to temperate regions. Three Echinochloa crus-galli accessions (EC-SNU1, EC-SNU2, and EC-SNU3) collected in Korea have shown diversity in their responses to flooding, with EC-SNU1 exhibiting the greatest growth among three accessions. In the search for molecular components underlying adaptive diversity among the three Echinochloa crus-galli accessions, we performed de novo assembly of leaf transcriptomes and investigated the pattern of differentially expressed genes (DEGs). Although the overall composition of the three leaf transcriptomes was well-conserved, the gene expression patterns of particular gene ontology (GO) categories were notably different among the three accessions. Under non-submergence growing conditions, five protein categories (serine/threonine kinase, leucine-rich repeat kinase, signaling-related, glycoprotein, and glycosidase) were significantly (FDR, q < 0.05) enriched in up-regulated DEGs from EC-SNU1. These up-regulated DEGs include major components of signal transduction pathways, such as receptor-like kinase (RLK) and calcium-dependent protein kinase (CDPK) genes, as well as previously known abiotic stress-responsive genes. Our results therefore suggest that diversified gene expression regulation of upstream signaling components conferred the molecular basis of adaptive diversity in Echinochloa crus-galli.

This study was conducted to establish a weed management system based on the sequential application of pre-emergence (PRE) and post-emergence (POST) herbicides for soybean production in Primorsky krai. Field experiments were conducted for two years in a field located in Bogatyrka, Primorsky krai, Russia (N43°49′, E131°36′). No herbicide application resulted in significant soybean yield loss, 0.03–0.3 t ha⁻¹, which is more than 91.6% yield loss compared with that of the weed-free plot. The PRE application of acetochlor showed good weed control efficacy (greater than 90% weed control) with acceptable soybean safety (less than 10% soybean damage), while the other PRE herbicides performed poorly in terms of weed control. The POST application of bentazon + acifluorfen, bentazon, and imazamox at 30 days after soybean sowing (DAS) showed good weed control efficacy with good soybean safety. Neither the PRE nor POST application alone showed a sufficient soybean yield protection, resulting in much lower soybean yield than the weed-free plot. The sequential application of acetochlor (PRE), followed by either bentazon + acifluorfen (POST) at 30 DAS in 2012 or bentazon + imazamox (POST) at 60 DAS in 2013 showed the best performance in soybean yields, 1.7 t and 1.9 t ha⁻¹, respectively, provided with 724.5 US$ and 1155.6 US$ ha⁻¹ of economic returns. For alternative PRE herbicides of acetochlor, which is now banned, our tests of the sequential application of S-metolachlor with other POST herbicides and the sole application of other PRE herbicides revealed that S-metolachlor and clomazone could also be considered. Our results thus demonstrate that the sequential applications of PRE and POST herbicides should be incorporated into the weed management system for soybean production in Primorsky krai, Russia.

Echinochloa 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 Echinochloa management; however, the potential risk for the development of herbicide resistance in Echinochloa species has not been well-investigated. Thus, this study was conducted to evaluate the baseline sensitivity of Echinochloa species to florpyrauxifen-benzyl to estimate the risk of future resistance development. A total of 70 and 71 accessions of Echinochloa crus-galli and Echinochloa oryzicola were collected from paddy fields in Korea, respectively. These two Echinochloa 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^–1. Nonlinear regression analyses revealed that GR₅₀ values for E. oryzicola ranged from 4.54 g to 29.66 g a.i. ha^–1, giving a baseline sensitivity index (BSI) of 6.53, while those for E. crus-galli ranged from 6.15 g to 16.06 g a.i. ha^–1, giving a BSI of 2.61. Our findings suggest that E. oryzicola has a greater potential risk than E. crus-galli for the development of metabolism-based resistance to florpyrauxifen-benzyl.