Abstract Paraquat (1,1’-dimethyl-4,4’-bipyridyl dichloride) is an herbicide widely used worldwide and officially banned in Brazil in 2020. Kidney lesions frequently occur, leading to acute kidney injury (AKI) due to exacerbated reactive O2 species (ROS) production. However, the consequences of ROS exposure on ionic transport and the regulator local renin-angiotensin-aldosterone system (RAAS) still need to be elucidated at a molecular level. This study evaluated how ROS acutely influences Na+-transporting ATPases and the renal RAAS. Adult male Wistar rats received paraquat (20 mg/kg; ip). After 24 h, we observed body weight loss and elevation of urinary flow and serum creatinine. In the renal cortex, paraquat increased ROS levels, NADPH oxidase and (Na++K+)ATPase activities, angiotensin II-type 1 receptors, tumor necrosis factor-α (TNF-α), and interleukin-6. In the medulla, paraquat increased ROS levels and NADPH oxidase activity but inhibited (Na++K+)ATPase. Paraquat induced opposite effects on the ouabain-resistant Na+-ATPase in the cortex (decrease) and medulla (increase). These alterations, except for increased serum creatinine and renal levels of TNF-α and interleukin-6, were prevented by 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl (tempol; 1 mmol/L in drinking water), a stable antioxidant. In summary, after paraquat poisoning, ROS production culminated with impaired medullary function, urinary fluid loss, and disruption of Na+-transporting ATPases and angiotensin II signaling. 1,1dimethyl4,4bipyridyl 11dimethyl44bipyridyl dimethylbipyridyl 1,1 dimethyl 4,4 bipyridyl 4 dichloride 2020 occur AKI (AKI O (ROS However reninangiotensinaldosterone renin aldosterone RAAS (RAAS level Na+transporting Natransporting Na+ transporting Na 20 (2 mg/kg mgkg mg kg ip. ip . ip) 2 h Na++K+ATPase NaKATPase Na++K+ ATPase K activities IItype type receptors factorα factor α TNFα, TNFα TNF , (TNF-α) interleukin6. interleukin6 interleukin 6. 6 interleukin-6 Na++K+ATPase. ATPase. ouabainresistant ouabain resistant Na+ATPase NaATPase decrease (decrease increase. increase (increase) alterations interleukin6, 6, 4hydroxy2,2,6,6tetramethylpiperidin1oxyl 4hydroxy2266tetramethylpiperidin1oxyl hydroxytetramethylpiperidinoxyl hydroxy 2,2,6,6 tetramethylpiperidin oxyl tempol (tempol mmolL mmol L water, water water) antioxidant summary poisoning function signaling 1dimethyl4 4bipyridyl 11 1, 44 4, 202 ( NaK Na++K (TNF-α interleukin- (increase 4hydroxy2 6tetramethylpiperidin1oxyl 2266 2,2,6, 1dimethyl 4hydroxy tetramethylpiperidinoxyl 226 2,2,6 22 2,2, 2,2 2,

Abstract: Background: Weeds pose a significant challenge to Argentine crops, leading to herbicide resistance and environmental concerns. Objective: To identify key weed problems, assess management practices, and herbicide use. Methods: A web-based survey system, with closed questions, was distributed from March to August 2020 among 147 agricultural stakeholders related to soybean, corn, wheat, and sunflower crops in Argentina. Results: Notable troublesome weeds included Conyza bonariensis (L.) Cronq., Digitaria sanguinalis (L.) Scop., Eleusine indica (L.) Gaertn., Amaranthus hybridus L., and Sorghum halepense (L.) Pers. Herbicide usage was as follows: 86% used burndown fallow chemical control, 51% adhered to labeled application rates, 40% applied herbicides at the labeled growth stage, and 37% rotated modes of action. Non-chemical controls were also employed, with 67% favoring crop rotation and 36% focused on preventing weed seed production. Glyphosate was the dominant herbicide, employed by over 90% of respondents. For summer crops, frequently used herbicides included paraquat, 2,4-D (80% of respondents), atrazine (60% of respondents), sulfentrazone, flumioxazin, S-metolachlor (60% of respondents), and clethodim (65% of respondents). In winter cereals, 2,4-D, flurochloridone, flumioxazin, and pyroxasulfone were the top choices. Conclusions: This survey underscores the high reliance on chemical control in Argentina's major crops. The findings provide crucial insights for regional policy planning, emphasizing the importance of integrating diverse weed management tactics. It also highlights the need for proactive integrated management strategies at the field level to mitigate and prevent weed issues in Argentina, offering a valuable approach for analyzing weed problems in extensive crops worldwide. Abstract Background concerns Objective practices use Methods webbased web based system questions 202 14 soybean corn wheat Argentina Results L. L (L. Cronq Cronq. Scop Scop. Gaertn Gaertn. Pers follows 86 51 rates 40 stage 37 action Nonchemical Non 67 36 production 90 respondents paraquat 2,4D 24D D 2,4 2 4 80% 80 (80 respondents, , respondents) 60% 60 (60 sulfentrazone flumioxazin Smetolachlor S metolachlor 65% 65 (65 . cereals 2,4D, D, flurochloridone choices Conclusions Argentinas s planning tactics worldwide 20 1 (L 8 5 3 6 9 4D 24 2, (8 (6 (

Abstract The objective of this work was to evaluate the effectiveness of herbicides when applied alone and in combinations at sourgrass (Digitaria insularis) post-emergence, as well as to identify a substitute to paraquat in sequential application. Field and greenhouse experiments were conducted during the 2019/2020 and 2020/2021 crop seasons. The herbicides applied alone and in combinations were: atrazine, clethodim, clodinafop, diquat, glufosinate, haloxyfop, imazapic, imazapyr, mesotrione, nicosulfuron, paraquat, glyphosate, saflufenacil, tembotrione, and tepraloxydim. In the 2019/2020 crop season, in the experiment conducted in the field, the control of sourgrass was considered low due to the dry weather condition and to the full flowering of the plants. In the greenhouse, a satisfactory control above 80% was observed at 28 days after herbicide application for most treatments. In the 2020/2021 crop season, under field conditions, the application of glyphosate combined with haloxyfop, with a sequential application of glufosinate, resulted in the highest weed control. In the greenhouse, most treatments were effective and, of these, all contained glufosinate. The sequential application of glufosinate or in combinations favors a better control of sourgrass. However, diquat and glufosinate do not differ in efficacy in sequential application and are an option for the control of the weed. Digitaria insularis postemergence, postemergence post emergence, emergence post-emergence 20192020 2019 2020 2019/202 20202021 2021 2020/202 seasons atrazine clethodim clodinafop haloxyfop imazapic imazapyr mesotrione nicosulfuron saflufenacil tembotrione tepraloxydim season plants 80 2 conditions these However 2019202 201 202 2019/20 2020202 2020/20 8 201920 20 2019/2 202020 2020/2 20192 2019/ 20202 2020/

Resumo O objetivo deste trabalho foi avaliar a eficácia de herbicidas quando aplicados isolados e em combinações na pós-emergência de capim-amargoso (Digitaria insularis), bem como identificar um substituto ao paraquat na aplicação sequencial. Experimentos em campo e em casa de vegetação foram conduzidos durante as safras de 2019/2020 e 2020/2021. Os herbicidas aplicados isolados e em combinações foram: atrazina, cletodim, clodinafope, diquate, glufosinato, haloxifope, imazapique, imazapir, mesotriona, nicossulfurom, paraquate, glifosato, saflufenacil, tembotriona e tepraloxidim. Na safra de 2019/2020, no experimento em campo, o controle de capim-amargoso foi considerado baixo devido às condições de clima seco e ao pleno florescimento das plantas. Na casa de vegetação, observou-se controle satisfatório acima de 80% aos 28 dias após a aplicação dos herbicidas para a maioria dos tratamentos. Na safra de 2020/2021, em condições de campo, a aplicação de glifosato combinado com haloxifope, com aplicação sequencial de glufosinato, resultou no maior controle da planta daninha. Na casa de vegetação, a maioria dos tratamentos foi eficaz e, destes, todos continham glufosinato. A aplicação sequencial de glufosinato ou em combinações favorece um melhor controle de capim-amargoso. No entanto, o diquate e o glufosinato não diferem em eficácia na aplicação sequencial e são opções de controle desta planta daninha. pósemergência pós emergência capimamargoso capim amargoso Digitaria insularis, insularis , insularis) 20192020 2019 2020 2019/202 20202021 2021 2020/2021 atrazina cletodim clodinafope haloxifope imazapique imazapir mesotriona nicossulfurom paraquate saflufenacil tepraloxidim plantas observouse observou se 80 2 daninha destes capimamargoso. amargoso. entanto 2019202 201 202 2019/20 2020202 2020/202 8 201920 20 2019/2 202020 2020/20 20192 2019/ 20202 2020/2 2020/

Abstract The aim of the present study was to investigate the effect of swertiamarin (STM) in attenuating paraquat (PQ)-induced human lung alveolar epithelial-like cell (A549) apoptosis and the underlying mechanisms. A549 cells were pretreated with different concentrations of STM for 2 hr and then cultured with or without PQ (700 μM) for 24 hr. Cell survival was determined using the CCK8 assay. Morphological changes, MDA content, inflammatory factors, fibrogenesis parameters, apoptosis rates, redox status and mitochondrial membrane potential (MMP) were evaluated. The expression of several genes involved in the modulation of redox status was measured by Western blotting. Cell viability and MMP were decreased, but the apoptosis rate and DCFH oxidation were elevated by PQ exposure. STM pretreatment notably increased cell viability and MMP and reduced the apoptosis rate and DCFH oxidation. Furthermore, TLR4- NOX4 signaling was significantly inhibited by STM. The downregulation of NOX4 by siRNA exerted the same protective effects as STM. This study provides the first evidence that STM attenuates PQ-induced pulmonary epithelial-like cell apoptosis via NOX4-mediated regulation of redox and mitochondrial function. (STM PQinduced induced epitheliallike epithelial like A (A549 mechanisms A54 700 (70 μM CCK assay changes content factors parameters rates (MMP evaluated blotting decreased exposure Furthermore TLR4 TLR NOX NOX4mediated NOXmediated mediated function (A54 A5 70 (7 (A5 7 ( (A

Resumen El paraquat es un plaguicida del grupo de los herbicidas asociado a una gran morbimortalidad, luego de su ingesta con intención suicida. Dentro de las ayudas pronósticas, en el paciente intoxicado por esta sustancia, la literatura internacional considera la tomografía de tórax y sus hallazgos, sin embargo, en Colombia, no hay reportes a nivel nacional, ni inclusión de este parámetro dentro de las guías del Ministerio de Salud. Reportamos el caso de una paciente con diagnóstico tardío de intoxicación por paraquat, la tomografía de ingreso no indicó compromiso pulmonar así que se inició tratamiento y se obtuvo resultados favorables relacionados con la supervivencia de la paciente.

Abstract Paraquat is a pesticide from the group of herbicides associated with high morbidity and mortality after ingestion with suicidal intent. Within the prognostic aids, in the patient intoxicated by this substance, the international literature considers the chest tomography and its findings. However, in Colombia, there are no reports at the national level, nor is there any inclusion of this parameter within the guidelines of the Ministry of Health. We report the case of a patient with a late diagnosis of paraquat poisoning, admission tomography did not indicate pulmonary compromise, so treatment was started and favorable results related to the patient's survival were obtained.

Resumen: Introducción. El herbicida paraquat constituye la primera causa de decesos por intoxicaciones en distintos países. Objetivo. Relacionar las características sociodemográficas y clínicas con la condición final de pacientes intoxicados por paraquat atendidos en un hospital del suroccidente de Colombia. Materiales y métodos. En este estudio observacional, descriptivo, analítico, transversal y retrospectivo, se revisaron las historias clínicas de pacientes atendidos por intoxicación con paraquat en una institución de tercer nivel de complejidad en Pasto (Colombia) entre el 2013 y el 2018. Se recolectó la información sobre la condición final (vivo o fallecido) de cada paciente, así como los datos sociodemográficos, clínicos y de los exámenes paraclínicos. Se establecieron comparaciones por grupos y se diseñó un modelo de regresión logística binaria. Resultados. Se filtró la información de 299 registros y se analizaron finalmente 160 casos. Las características relacionadas con la condición final de los pacientes fueron el tiempo de estancia (OR=0,124; IC95% 0,03-0,6; p=0,009), la frecuencia cardiaca (OR=35,65; IC95% 1,44-884,78; p=0,029) y la creatinina inicial (OR=1,73; IC95% 1,23-2,44; p=0,002). Conclusiones. La proporción de la letalidad fue mayor entre los pacientes con estancia hospitalaria corta, taquicardia y elevación de la concentración sérica de creatinina al ingreso. Este reporte puede ser útil como fundamento de una escala de gravedad para detectar a los pacientes con resultados adversos en la fase temprana para que puedan recibir una intervención oportuna.

Abstract Introduction: Paraquat is an agrochemical that constitutes the first cause of death by poisoning in different countries. Objective: To relate sociodemographic and clinical characteristics with the final condition of patients intoxicated by paraquat in a hospital in southwestern Colombia. Materials and methods: This was an observational, descriptive, analytical, crosssectional, and retrospective study. We reviewed the medical records of patients diagnosed with paraquat poisoning at a level III hospital in Pasto, Colombia, from 2013 to 2018. We collected the data regarding their final condition (alive or deceased) and their sociodemographic, clinical, and paraclinical information. We established group comparisons and designed a binary logistic regression model. Results: We reviewed 299 records and, after the exclusion, we analyzed 160 cases. The characteristics related to the final condition of the patients were length of stay (OR = 0.124; 95% CI: 0.03-0.6; p = 0.009), heart rate (OR = 35.65; 95% CI: 1.44-884.78; p = 0.029), and initial creatinine (OR = 1.73; 95% CI: 1.23-2.44; p = 0.002). Conclusion: The proportion of case fatality was higher in patients with short hospital stay times and elevated heart rates and admission creatinine levels. This report may be useful as a rationale for the creation of a severity scale for the early detection of patients with adverse outcomes and their timely treatment.

RESUMEN ''Anemia macrocítico-normocrómica en el bagre africano Clarias gariepinus (Siluriform: Clariidae) expuesto a Paraquat en laboratorio'' Introducción: Los plaguicidas agrícolas se encuentran entre las principales causas de contaminación en los ecosistemas acuáticos y pueden provocar cambios fisiológicos en los peces. Por ejemplo, la alteración de la sangre y el daño al tejido hematopoyético pueden estar asociados con condiciones patológicas relacionadas con el agua. Objetivo: Describir los efectos de ciertos niveles de plaguicidas en una especie de pez de Nigeria. Métodos: Se indujo anemia macrocítico-normocrómica en C. gariepinus a intervalos de 1, 7 y 14 días (concentraciones subletales de Paraquat: 0; 0,03; 0,05; 0,07 and 0,09mg/l). Resultados: Hubo discrasias sanguíneas con una disminución significativa (p <0,05) de hemoglobina, hematocrito, glóbulos rojos, glóbulos blancos, linfocitos y monocitos, el volumen corpuscular medio (MCV), la hemoglobina corpuscular media (MCH), los neutrófilos, eosinófilos y basófilos aumentaron significativamente (p <0,05) con concentraciones crecientes del tóxico, mientras que la concentración de hemoglobina corpuscular media (MCHC) se mantuvo normal. Conclusión: Las concentraciones subletales de paraquat generaron anemia macrocítico-normocrómica en el bagre C. gariepinus.

ABSTRACT Introduction: Agricultural pesticides are among the main causes of pollution in aquatic ecosystems, and they can lead to physiological changes in fish. For example, blood alteration and damage to haemopoietic tissue can be associated with pathological conditions related to water. Objective: To describe the effects of certain levels of pesticide on a Nigerian fish species. Methods: Macrocytic-normochromic anaemia was induced in C. gariepinus at intervals of 1,7 and 14 days (sub-lethal concentrations of Paraquat: 0; 0,03; 0,05; 0,07 and 0,09mg/l). Results: Blood dyscrasias was observed with a significant (p<0,05) decrease in haemoglobin, haematocrit, red blood cells, white blood cells, lymphocytes and monocytes. Mean corpuscular volume (MCV), Mean corpuscular haemoglobin (MCH), Neutrophils, Eosinophil and Basophil increased significantly (p<0,05) with increasing concentrations of the toxicant while Mean corpuscular haemoglobin concentration (MCHC) remained normal. Conclusion: Sublethal concentrations of paraquat induced macrocytic-normochromic anaemia in the catfish C. gariepinus.

Paraquat is an herbicide widely used for weed control in Chile. Its intake determines a high probability of mortality because of its inherent toxicity through the production of free radicals. Multiple organs are affected, mainly the lungs; to this is added the lack of effective treatment. We present the clinical case of an 18-year-old man who in a suicidal attempt swallows 50 mL of paraquat (200 g/L), with a fatal outcome. The clinical presentation depends on the amount of Paraquat ingested. Radiological findings described vary according to the temporality of the condition and could even determine the prognosis

Resumen El Paraquat es un herbicida ampliamente utilizado para el control de las malezas en Chile. Su ingesta determina una alta probabilidad de mortalidad dado su inherente toxicidad mediante la producción de radicales libres, que afectan a múltiples órganos, principalmente los pulmones; a esto se suma la falta de un tratamiento efectivo. Se presenta el caso clínico de un hombre de 18 años que en un intento suicida consume 50 mL de paraquat (200 g/L), con desenlace fatal. La presentación clínica depende la cantidad de Paraquat ingerida y los hallazgos radiológicos descritos varían según la temporalidad del cuadro e, inclusive, podrían determinar el pronóstico.

Abstract Background Paraquat is a broad spectrum herbicide used particularly in burndown, in pre-plant of row crops and in the pre-harvest desiccation of some crops. In Brazil, paraquat was re-evaluated by Anvisa, leading to a prohibition of production and sales on September 22, 2020, and used until July 31, 2021. Objective The objective of this review is to characterize the use of paraquat in Brazil and describe the status in other countries, particularly the agronomic implications of its ban, possible replacements, and scenarios. Review The use of paraquat is important for weed management in different production systems. Owing to its toxicity, its use has been re-evaluated in several countries. For pre-harvest desiccation of soybeans, diquat, glufosinate, and some combinations with Protox inhibitors are highlighted as alternatives to paraquat. For pre-harvest desiccation of common beans, diquat, saflufenacil, and glufosinate could be used; however, only glufosinate could be used for wheat. For managing broadleaves weeds, glufosinate, saflufenacil, carfentrazone, and diquat are effective alternatives. Diquat may be less effective in controlling Conyza spp. resistant to paraquat. For grasses control, glufosinate, in addition to ACCase inhibitors and possible mixtures, may be helpful. Although pre-emergent herbicides are not classified as desiccant herbicides, they contribute to weed management. The adoption of herbicide-tolerant crops, mechanical control, and cover crops can be added as agricultural practices for integrated weed management. Conclusions Due to the ban on paraquat, challenges arise, and the most often suggested replacements are glufosinate, diquat, and Protox inhibitors; however, grass control will be of greater concern. burndown preplant pre plant preharvest harvest reevaluated re evaluated Anvisa 22 2020 31 2021 countries scenarios systems toxicity soybeans beans saflufenacil however wheat weeds carfentrazone spp mixtures helpful preemergent emergent herbicidetolerant tolerant arise concern 2 202 3 20

Abstract Evaluation of montmorillonite for paraquat by in vitro and in vivo test. In vitro test were evaluated by a batch test, taking the paraquat concentration, adsorbents, reaction environment and time as indices, the absorption rate was screened by orthogonal design. In vivo test was executed with rabbits. Group 1: 4 rabbits dosed with montmorillonite. Group 2: 8 rabbits dosed with 200 mg/kg paraquat. Group 3: 6 rabbits dosed with 200 mg/kg paraquat then gavage with montmorillonite 5 min later. Group 4: 6 rabbits dosed with 200 mg/kg paraquat then gavage with montmorillonite 30 min later. Blood paraquat concentration, serum cytokines, blood gas analysis and histopathology of lung were implemented. In vitro test found that all the four factors influence the absorption rate of paraquat (P < 0.05). In vitro test found that oral montmorillonite could change toxicokinetics parameters of paraquat (P < 0.05); decrease raised serum TGF-β1 and HMGB1 (P < 0.05) and alleviate the histopathology damage of lung. Montmorillonite might exert its protective effects on paraquat induced damage. concentration adsorbents indices design 1 2 20 mgkg mg kg 3 later cytokines implemented P 0.05. 005 0.05 . 0 05 TGFβ1 TGFβ TGF β1 β TGF-β HMGB 00 0.0 0.

Abstract Bidens pilosa L. is a species of plant that grows wild. It is commonly found in abundance in the Mekong Delta region of Vietnam. This study aimed to investigate the chemical composition, in vitro and in vivo antioxidant activity, the antimicrobial activity against some aquatic pathogenic bacteria and antifungal activity against plant pathogenic bacteria of Bidens pilosa L. extract. The results showed that Bidens pilosa L. extract had good antioxidant capacity through all four test methods of DPPH, ABTS●+, RP, and TAC with the EC50 values of 455.78 ± 3.28 μg/mL, 148.68 ± 2.02 μg/mL, 462.09 ± 12.57 μg/mL and 139.14 ± 4.34 μg/mL, respectively. Fruit flies fed on a diet supplemented with 0.5 g/mL of Bidens pilosa L. extract had an average lifespan of 2.15 times and 1.54 times longer under oxidative stress using 20 mM Paraquat and H2O2 10%, respectively. In addition, the total polyphenols and total flavonoids in the extract were also determined to be 107.49 ± 4.04 mg GAE/g and 165.63 ± 2.90 mg QE/g, respectively. Regarding the antimicrobial activity, the ethanol extract of Bidens pilosa L. showed stronger resistance to Gram (+) S. agalactiae than the tested Gram (-) bacteria, including A. hydrophila, E. ictaluri, and A. dhakensis. In addition, the ethanol extract from Bidens pilosa L. also showed the better ability to inhibit the growth of the fungus Colletotrichum sp. (MIC = 1250 µg/mL) than that of Fusarium oxysporum (MIC = 2500 µg/mL).

ABSTRACT Agriculture in the Yucatán Peninsula, Mexico, grew last year, and pesticide use problems have been reported; however, there is no information about the use and management of pesticides in farms. In this study, the main pesticides used by farmers were identified in two types of agriculture: open-air (milpa) (OA) and enclosed area (shade house and greenhouse) (EA), in order to evaluate their use and management and the related environmental and health perceptions of users. Surveys (38 questions) were applied to 39 farmers in the study area, which consisted of 14 localities in Yucatán State. The most cultivated products were habanero pepper (Capsicum chinense) for enclosed-areas and maize (Zea mays) for open-air agriculture. The use of 33 active ingredients was reported. Some of them have restrictions in México (i.e., dicofol and methamidophos). Paraquat was the most used of all pesticides reported. Organophosphorus pesticides (OP) were the most used. Farmers know about the environmental and health risks related to pesticide use; however, a lack of knowledge about the misuse of these products was evident. The surveys showed deficiencies in personal protection during application and incorrect disposal of empty containers and wastes. The analysis showed that the behavior of farmers about pesticide management and their perception of damage to health and the environment were multifactorial. The results conclude that farmers’ personal aspects (i.e., language, education) are the leading cause of problems associated with pesticide misuse and the lack of information and training, representing a risk for human health and the environment.

RESUMEN La agricultura en la Península de Yucatán, México, creció en los últimos años, reportando problemas con el uso de plaguicidas; sin embargo, no existe información al respecto en la región. Este estudio identificó los principales plaguicidas utilizados en la agricultura al aire libre (milpa) (OA) y en áreas cerradas (áreas techadas e invernaderos) (EA); se evaluó su uso y manejo, así como la percepción ambiental y de salud de los agricultores al emplearlos. Se aplicaron 39 encuestas (38 preguntas) en el área de estudio (14 localidades de Yucatán). Los productos más cultivados fueron el chile habanero (Capsicum chinense) para áreas cerradas y el maíz (Zea mays) para agricultura al aire libre. Se reportó el uso de 33 ingredientes activos, algunos cuyo uso está restringido en México (p.ej., dicofol y metamidofos). El paraquat fue el plaguicida mas empleado. Los plaguicidas organofosforados (OP) fueron los más utilizados. Los agricultores conocen los riesgos a la salud y el ambiente por el uso de plaguicidas; sin embargo, fue evidente la falta de conocimiento sobre su uso indebido. Las encuestas mostraron deficiencias en la protección personal durante la aplicación y eliminación incorrecta de contenedores vacíos y residuos. Los análisis mostraron que el comportamiento de los agricultores sobre el manejo de plaguicidas y su percepción del daño a la salud y al ambiente fue multifactorial. Los resultados concluyen que los aspectos personales de los agricultores (idioma y educación) son la principal causa de problemas asociados con el uso indebido de plaguicidas y la falta de información y capacitación, lo que representa un riesgo para la salud humana y el medioambiente.

Abstract Background Agriculture in South America (SA) had a great expansion in the last decades and weed control changed accordingly with region and crop practices. Objective The objective of this review is to present the history of herbicide use and discuss the main changes in weed management in SA. Methods Herbicide use quantities were obtained from official institutions and commercial organizations in Argentina, Brazil, Chile, Paraguay and Uruguay. Data were summarized per active ingredient, herbicide mode of action or crop. The evolution of the cultivated area of the main crops in each country, and the crop and weed management associated to it were considered to discuss the importance and the consequences of the main herbicides used. Results In 2019 the most used herbicides in Brazil were glyphosate, 2,4-D, atrazine, paraquat and diuron representing 62, 15, 7, 5 and 2% of the total amount used. In Argentina, the increasing selection of herbicide resistant populations (4 cases/year), resulted in utilization of older chemistries. Weed control in Uruguay is traditionally benefited from crop/pasture rotations but recently is also facing problems of continuous cropping systems. Agriculture in Chile is more diverse, but similar patterns and problems of herbicide use are present. Conclusions Intensification of agriculture, no-tillage, glyphosate resistant crops, and herbicide resistant weeds were the most important drivers of herbicide use changes in SA. Integrated weed management is unpostponable to provide sustainable increasing food production in SA.

Resumo O aumento na produtividade deve estar atrelado ao controle efetivo dos custos de produção. Assim, o controle químico e seletivo das plantas daninhas é um método adequado, pois proporciona economia de trabalho e energia, demanda pouca mão de obra e permite o controle durante todo o ciclo de cultivo. O presente trabalho teve como objetivo avaliar a sensibilidade da cultura do abacateiro aos efeitos fitotóxicos da aplicação de herbicidas em pós-emergência. O experimento foi instalado utilizando-se de sementes de abacate da cultivar Margarida e conduzido em casa de vegetação no Setor de Fruticultura do Departamento de Agricultura, da Universidade Federal de Lavras. O delineamento experimental utilizado foi de blocos ao acaso, com 4 repetições e 8 tratamentos e cada parcela experimental foi composta por três mudas. Os herbicidas paraquat, oxyfluorfen, fomesafem, carfentrazone-ethyl e glyphosate causaram danos às mudas de abacateiro e não devem ser recomendados com base na dosagem comercial utilizada. O paraquat causou a morte das plantas em 30 dias após a aplicação. Os tratamentos com Fluasifope-p- butílico e Imazetapir demonstraram ser os mais promissores para uso em área de implantação de pomares de abacateiros pois causaram menores danos à cultura.

Abstract An increase in crop productivity should be linked to the effective control of production costs. Thus, the chemical and selective control of weeds is an appropriate method because it saves labor and energy, requires little manpower, and allows control throughout the crop cycle. The present study aimed to evaluate the sensitivity of avocado seedlings to the phytotoxic effects of postemergence herbicide application. The experiment was carried out on avocado seeds of the cultivar Margarida in a greenhouse in the fruit sector of the Department of Agriculture, Federal University of Lavras. The experimental design was randomized block design, with four replicates and eight treatments, and each experimental plot consisted of three seedlings. The herbicides paraquat, oxyfluorfen, fomesafem, carfentrazone-ethyl, and glyphosate caused damage to avocado seedlings and should not be recommended based on the commercial dosage used. Paraquat caused the plants to die within 30 days after application. Fluazifop-p-butyl and imazethapyr proved to be the most promising for use in avocado orchards because they caused less damage to the crop.

Abstract Background: Aerobic metabolism generates reactive oxygen species that may cause critical harm to the cell. The aim of this study is the characterization of the stress responses in the model aromatic degrading bacterium Paraburkholderia xenovorans LB400 to the oxidizing agents paraquat and H 2 O2. Methods: Antioxidant genes were identified by bioinformatic methods in the genome of P. xenovorans LB400, and the phylogeny of its OxyR and SoxR transcriptional regulators were studied. Functionality of the transcriptional regulators from strain LB400 was assessed by complementation with LB400 SoxR of null mutant P. aeruginosa ΔsoxR, and the construction of P. xenovorans pIZ oxyR that overexpresses OxyR. The effects of oxidizing agents on P. xenovorans were studied measuring bacterial susceptibility, survival and ROS formation after exposure to paraquat and H 2 O2. The effects of these oxidants on gene expression (qRT PCR) and the proteome (LC–MS/MS) were quantified. Results: P. xenovorans LB400 possesses a wide repertoire of genes for the antioxidant defense including the oxyR , ahpC , ahpF , kat , trxB , dpsA and gorA genes, whose orthologous genes are regulated by the transcriptional regulator OxyR in E. coli . The LB400 genome also harbors the soxR, fumC , acnA , sodB , fpr and fldX genes, whose orthologous genes are regulated by the transcriptional regulator SoxR in E. coli . The functionality of the LB400 soxR gene was confirmed by complementation of null mutant P. aeruginosa Δ soxR . Growth, susceptibility, and ROS formation assays revealed that LB400 cells were more susceptible to paraquat than H2O2. Transcriptional analyses indicated the upregulation of the oxyR , ahpC1 , katE and ohrB genes in LB400 cells after exposure to H2O2, whereas the oxyR , fumC , ahpC1 , sodB1 and ohrB genes were induced in presence of paraquat. Proteome analysis revealed that paraquat induced the oxidative stress response proteins AhpCF and DpsA, the universal stress protein UspA and the RNA chaperone CspA. Both oxidizing agents induced the Ohr protein, which is involved in organic peroxide resistance. Notably, the overexpression of the LB400 oxyR gene in P. xenovorans significantly decreased the ROS formation and the susceptibility to paraquat, suggesting a broad OxyR regulated antioxidant response. Conclusions: This study showed that P. xenovorans LB400 possess a broad range oxidative stress response, which explain the high resistance of this strain to the oxidizing compounds paraquat and H2O2.