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Off‐target drift of herbicides can seriously reduce peanut (Arachis hypogea L.) growth and yield and is of great concern to growers who will need to manage sensitive crops near new herbicide‐tolerant crops. Field experiments were conducted in 2021 and 2022 with 25% labeled rates of dicamba, glufosinate, glyphosate, lactofen, and paraquat to simulate drift on peanut. The objective was to evaluate the effects of low‐rate application of the herbicides on peanut injury and yield reductions and to determine if unmanned aerial vehicle (UAV) imagery‐based normalized difference vegetation index (NDVI) provides accurate estimation of peanut injury from the herbicides applied at vegetative (V3) and reproductive (R3) growth stages. Peanut suffered greater yield reduction (33%) when exposed to the herbicides at R3 than at V3 growth stage (19%) across all herbicides applied. The order of herbicides that induced yield reductions in peanut was glyphosate > glufosinate = dicamba > paraquat = lactofen. Regardless of exposure timing, NDVI values generated from UAV imagery could not differentiate paraquat or lactofen injury from the weed‐free check. However, NDVI values could differentiate between injured and weed‐free check plants up to 2 and 4 weeks after treatment (WAT) for dicamba at R3 and V3 exposure timing, respectively, up to 4 WAT for glufosinate, and 8 WAT for glyphosate. NDVI from aerial imagery may be helpful to accelerate the detection of injury in large hectarages with greater accuracy compared with visual injury rating, which can be influenced by individual estimation bias. Core Ideas Peanut yield loss from 25% labeled rates of selected herbicides was greater at reproductive than at vegetative stage. Peanut was most susceptible to glyphosate (59%) and expressed the greatest tolerance to lactofen (≤10%). The order of yield reduction from the herbicides was glyphosate > glufosinate = dicamba > paraquat = lactofen.

Despite widespread adoption of dicamba/glyphosate‐resistant (DGR) soybean [Glycine max (L.) Merr.] in Nebraska and across the United States in recent years, economic information comparing herbicide programs with glufosinate‐resistant (GLU‐R) and conventional soybean is not available. The objectives of this study were to evaluate weed control efficacy, crop safety, gross profit margin, and benefit/cost ratios of herbicide programs with multiple sites of action in DGR, GLU‐R, and conventional soybean. Field experiments were conducted in 2018 and 2019 at three irrigated and two rain‐fed locations across Nebraska, for a total of 10 site‐years. Herbicides applied pre‐emergence (PRE) that included herbicides with three sites of action provided 85–99% control of common lambsquarters (Chenopodium album L.), Palmer amaranth (Amaranthus palmeri S. Watson), velvetleaf (Abutilon theophrasti Medik.), and a mixture of foxtail (Seteria spp.) and Poaceae species. Pre‐emergence herbicides evaluated in this study provided 72–96% weed biomass reduction and 61‒79% weed density reductions compared with the nontreated control. Herbicides applied post‐emergence (POST; dicamba plus glyphosate, glyphosate, glufosinate, and acetochlor plus clethodim plus lactofen) provided 93–99% control of all weed species 28 d after POST (DAPOST). Herbicides applied POST provided 89–98% weed biomass reduction and 86–96% density reduction at 28 DAPOST. For individual site‐years, yield was often similar for PRE followed by POST herbicide programs in herbicide‐resistant (HR) and conventional soybean. Gross profit margins and benefit/cost ratios were higher in HR soybean than in conventional soybean, although price premiums for conventional soybean can help compensate for increased herbicide costs.

Diphenyl ether herbicides, typical globally used herbicides, threaten the agricultural environment and the sensitive crops. The microbial degradation pathways of diphenyl ether herbicides are well studied, but the nitroreduction of diphenyl ether herbicides by purified enzymes is still unclear. Here, the gene dnrA, encoding a nitroreductase DnrA responsible for the reduction of nitro to amino groups, was identified from the strain Bacillus sp. Za. DnrA had a broad substrate spectrum, and the Km values of DnrA for different diphenyl ether herbicides were 20.67 μM (fomesafen), 23.64 μM (bifenox), 26.19 μM (fluoroglycofen), 28.24 μM (acifluorfen), and 36.32 μM (lactofen). DnrA also mitigated the growth inhibition effect on cucumber and sorghum through nitroreduction. Molecular docking revealed the mechanisms of the compounds fomesafen, bifenox, fluoroglycofen, lactofen, and acifluorfen with DnrA. Fomesafen showed higher affinities and lower binding energy values for DnrA, and residue Arg244 affected the affinity between diphenyl ether herbicides and DnrA. This research provides new genetic resources and insights into the microbial remediation of diphenyl ether herbicide-contaminated environments.Key points• Nitroreductase DnrA transforms the nitro group of diphenyl ether herbicides.• Nitroreductase DnrA reduces the toxicity of diphenyl ether herbicides.• The distance between Arg244 and the herbicides is related to catalytic efficiency.

Waterhemp has become a serious management challenge for field crop growers in New York. Two putative glyphosate-resistant (GR) waterhemp populations (NY1 and NY2) were collected in 2023 from two soybean fields in Seneca County, NY. The objectives of this research were to 1) confirm and characterize the level of glyphosate resistance in waterhemp populations from New York relative to a known glyphosate-susceptible population from Nebraska (NE_SUS), and 2) evaluate the efficacy of various postemergence herbicides for GR waterhemp control. Based on the shoot dry weight reductions (GR50 values) in a dose-response study, the NY1 and NY2 populations exhibited 5.6- to 8.3-fold resistance to glyphosate compared with the NE_SUS population. In a separate study, postemergence herbicides such as dicamba, glufosinate, lactofen, and 2,4-D applied alone or in a mixture with glyphosate or glufosinate had provided 89% to 99% control and ≥97% shoot dry weight reduction of NY1 and NY2 populations 21 d after treatment. Greater than 98% control of the NE_SUS population was achieved with tested postemergence herbicides, except mesotrione (62% control). Furthermore, atrazine, chlorimuron + thifensulfuron, and mesotrione were the least effective in controlling NY1 and NY2 populations (42% to 59% control and 50% to 67% shoot dry weight reductions, respectively). These results confirm the first report of GR waterhemp in New York. Growers should adopt effective alternative postemergence herbicides tested in this study to manage GR waterhemp. Nomenclature: Atrazine; chlorimuron; dicamba; glufosinate; glyphosate; lactofen; mesotrione; thifensulfuron; 2,4-D; waterhemp; Amaranthus tuberculatus (L.)

Herbicides that inhibit protoporphyrinogen oxidase (PPO) are used in more than 40 agronomic and specialty crops across Georgia to manage weeds through residual and postemergence (POST) control. In 2017, a population of Palmer amaranth exhibiting reduced sensitivity to POST applications of PPO-inhibiting herbicides was identified by the University of Georgia. Seed were collected from the site along with a known sensitive population; distance between the samples was 200 m, increasing the likelihood of similar environmental and genetic characteristics. To quantify sensitivity for both preemergence (PRE) and POST uses, 21 greenhouse dose-response assessments were conducted from 2017 to 2022. After conducting initial rate-response studies, 13 doses per herbicide were chosen for the POST experiment; field use rates of fomesafen (420 g ai ha–1), lactofen (219 g ai ha–1), acifluorfen (420 g ai ha–1), and trifludimoxazin (25 g ai ha–1) ranging from 0× to 4× the field use rate for the susceptible population, and 0× to 40× for the suspect population were applied. Herbicide treatments included adjuvants and were applied to plants 8 to 10 cm in height. Relative resistance factors (RRFs) were calculated for control ratings, mortality, and biomass, and ranged from 105 to 318, 36 to 1,477, 215 to 316, and 9 to 49 for fomesafen, lactofen, acifluorfen, and trifludimoxazin, respectively. In the PRE experiment, herbicide applications included five to nine doses of fomesafen (1× = 210 g ai ha–1), flumioxazin (1× = 57 g ai ha–1), oxyfluorfen (1× = 561 g ai ha–1), and trifludimoxazin (1× = 38 g ai ha–1); doses ranged from 0× to 6× for the suspect population and 0× to 2× for the susceptible population. Visual control, mortality, and biomass RRFs ranged from 3 to 5 for fomesafen, 21 to 31 for flumioxazin, 6 to 22 for oxyfluorfen, and 8 to 38 for trifludimoxazin. Results confirm that a Georgia Palmer amaranth population is resistant to PPO-inhibiting herbicides applied both PRE and POST. Nomenclature: Aciflurofen; flumioxazin; fomesafen; lactofen; oxyfluorfen; trifludimoxazin; Palmer amaranth; Amaranthus palmeri S. Watson; cotton; Gossypium hirsutum L.; peanut, Arachis hypogaea L.; soybean, Glycine max (L.)

Recent concerns regarding herbicide spray drift, its subsequent effect on the surrounding environment, and herbicide efficacy have prompted applicators to focus on methods to reduce off-target movement of herbicides. Herbicide applications are complex processes, and as such, few studies have been conducted that consider multiple variables that affect the droplet spectrum of herbicide sprays. The objective of this study was to evaluate the effects of nozzle type, orifice size, herbicide active ingredient, pressure, and carrier volume on the droplet spectra of the herbicide spray. Droplet spectrum data were collected on 720 combinations of spray-application variables, which included six spray solutions (five herbicides and water alone), four carrier volumes, five nozzles, two orifice sizes, and three operating pressures. The laboratory study was conducted using a Sympatec laser diffraction instrument to determine the droplet spectrum characteristics of each treatment combination. When averaged over each main effect, nozzle type had the greatest effect on droplet size. Droplet size rankings for nozzles, ranked smallest to largest using volume median diameter (Dv0.5) values, were the XR, TT, AIXR, AI, and TTI nozzle with 176% change in Dv0.5 values from the XR to the TTI nozzle. On average, increasing the nozzle orifice size from a 11003 orifice to a 11005 increased the Dv0.5 values 8%. When compared with the water treatment, cloransulam (FirstRate) did not change the Dv0.5 value. Clethodim (Select Max), glyphosate (Roundup PowerMax), lactofen (Cobra), and glufosinate (Ignite) all reduced the Dv0.5 value 5, 11, 11, and 18%, respectively, when compared with water averaged over the other variables. Increasing the pressure of AIXR, TT, TTI, and XR nozzles from 138 to 276 kPa and the AI nozzle from 276 to 414 kPa decreased the Dv0.5 value 25%. Increasing the pressure from 276 to 414 kPa and from 414 to 552 kPa for the same nozzle group and AI nozzle decreased the Dv0.5 value 14%. Carrier volume had the least effect on the Dv0.5 value. Increasing the carrier volume from 47 to 187 L ha−1 increased the Dv0.5 value 5%, indicating that droplet size of the herbicides tested were not highly dependent on delivery volume. The effect on droplet size of the variables examined in this study from greatest effect to least effect were nozzle, operating pressure, herbicide, nozzle orifice size, and carrier volume. Nomenclature: Clethodim; cloransulam; glufosinate; glyphosate; lactofen. Recientemente ha habido preocupación por la deriva producto de la aplicación de herbicidas, su subsecuente efecto en el ambiente de los alrededores, y la eficacia del herbicida, lo que ha obligado a los aplicadores a enfocarse en métodos para reducir el movimiento de herbicidas a zonas fuera del objetivo deseado. Las aplicaciones de herbicidas son procesos complejos, y como tales, se han realizado pocos estudios que consideren múltiples variables que afectan el espectro de gotas producto de la aspersión del herbicida. Los objetivos de este estudio fueron elucidar los efectos del tipo de boquilla, el tamaño del orificio, el ingrediente activo del herbicida, la presión, y el volumen de aplicación sobre el espectro de gotas de la aspersión del herbicida. Los datos del espectro de gotas fueron colectados para 720 combinaciones de variables de aplicación-aspersión, las cuales incluyeron seis soluciones de aspersión (cinco herbicidas y agua sola), cuatro volúmenes de aplicación, cinco boquillas, dos tamaños de orificio, y tres presiones de operación. El estudio de laboratorio fue realizado usando un instrumento Sympactec de difracción láser para determinar las características del espectro de gotas para cada combinación de tratamientos. Al promediar los resultados por efecto principal, el tipo de boquilla tuvo el mayor efecto en el tamaño de gota. El ranking de tamaño de gota para boquillas, de más pequeña a más grande, usando valores de diámetro medio (Dv0.5), fue XR, TT, AIXR, AI, y TTI con 176% de cambio en los valores de Dv0.5. En promedio, el incrementar el tamaño del orificio de la boquilla de un orificio 11003 a uno 11005 aumentó los valores Dv0.5 en 8%. Cuando se comparó con el tratamiento con agua, cloransulam (FirstRate) no cambió el valor de Dv0.5. Clethodim (Select Max), glyphosate (Roundup PowerMax), lactofen (Cobra), y glufosinate (Ignite) redujeron los valores de Dv0.5 en 5, 11, 11, y 18%, respectivamente, cuando se compararon con agua al promediarse sobre las otras variables. El incrementar la presión de las boquillas AIXR, TT, TTI, y XR de 138 a 276 kPa y la boquilla AI de 276 a 414 kPa disminuyó el valor de Dv0.5 en 25%. El aumentar la presión de 276 a 414 kPa y de 414 a 552 kPa para el mismo grupo de boquillas y la boquilla AI disminuyó Dv0.5 en 14%. El volumen de aplicación tuvo el menor efecto en el valor de Dv0.5. Al aumentar el volumen de aplicación de 47 a 187 L ha−1 se incrementó el valor de Dv0.5 en 5%, indicando que el tamaño de gota de los herbicidas evaluados no fue altamente dependiente del volumen de aplicación. El efecto sobre el tamaño de gota de las variables examinadas en este estudio de mayor a menor efecto fue: boquilla, presión de operación, herbicida, tamaño del orificio de la boquilla, y el volumen de aplicación.

Glufosinate serves as both a primary herbicide option and a complement to glyphosate and other postemergence herbicides for managing herbicide-resistant weed species. Enhancing broadleaf weed control with glufosinate through effective mixtures may mitigate further herbicide resistance evolution in soybean and other glufosinate-resistant cropping systems. Two field experiments were conducted in 2020 and 2021 at four locations in Wisconsin (Arlington, Brooklyn, Janesville, and Lancaster) and one in Illinois (Macomb) to evaluate the effects of postemergence-applied glufosinate mixed with inhibitors of protoporphyrinogen oxidase (PPO) (flumiclorac-pentyl, fluthiacet-methyl, fomesafen, and lactofen; Group 14 herbicides), bentazon (a Group 6 herbicide), and 2,4-D (a Group 4 herbicide) on waterhemp control, soybean phytotoxicity, and yield. The experiments were established in a randomized, complete block design with four replications. The first experiment focused on soybean phytotoxicity 14 d after treatment (DAT) and yield in the absence of weed competition. All treatments received a preemergence herbicide, with postemergence herbicide applications occurring between the V3 and V6 soybean growth stages, depending on the site-year. The second experiment evaluated the effect of herbicide treatments on waterhemp control 14 DAT and on soybean yield. Lactofen, applied alone or with glufosinate, produced the greatest phytotoxicity to soybean at 14 DAT, but this injury did not translate into yield loss. Mixing glufosinate with 2,4-D, bentazon, and PPO-inhibitor herbicides did not increase waterhemp control, nor did it affect soybean yield compared to when glufosinate was applied alone, but it may be an effective practice to reduce selection pressure for glufosinate-resistant waterhemp. Nomenclature: Bentazon; glufosinate; flumiclorac-pentyl; fluthiacet-methyl; fomesafen; waterhemp; Amaranthus tuberculatus (Moq.) Sauer; soybean, Glycine max (L.) Merr.

Palmer amaranth is an increasing concern for producers in the northeastern United States. A new Palmer amaranth population (NY_PA) was identified in a soybean field in Ontario County, New York, in 2024. The main objectives of this research were to 1) confirm whether this NY_PA population is resistant to glyphosate and atrazine, and 2) determine the effectiveness of various postemergence herbicides alone or in mixtures to control it. Along with the NY_PA population, two previously known glyphosate-resistant Palmer amaranth populations from Connecticut (CT_PA) and Kansas (KS_PA), and a known glyphosate-susceptible population from Alabama (AL_SUS) were also evaluated. Results from the quantitative polymerase chain reaction assay revealed that the NY_PA population had an average of 180 copies of the 5-enolpyruvylshikimate-3-phosphate synthase ( EPSPS ) gene with a single EPSPS gene copy in the AL_SUS population. A greenhouse dose-response study revealed that the NY_PA and CT_PA populations had 7-fold to 11-fold resistance to atrazine. Nearly all postemergence herbicides tested, including 2,4-D, dicamba, saflufenacil, glufosinate, and lactofen alone or in mixtures with 2,4-D, dicamba, and glufosinate, provided effective control (90% to 100%) of Palmer amaranth weeds collected in Connecticut, Kansas, and New York. All these postemergence herbicides, alone or in mixtures, reduced shoot dry biomass of all three populations by 82% to 97% compared with plants in nontreated control plots. These results confirm the first report of Palmer amaranth populations from New York and Connecticut with resistance to multiple herbicides (glyphosate and atrazine). Effective postemergence herbicides tested in this research can be used to manage these Palmer amaranth populations.

A sensitive and rapid method for the simultaneous determination of twenty herbicides (aclonifen, lactofen, terbutryn, butylate, carbetamide, fluazifop-P-butyl, propanil, prometryn, isoproturon, terbumeton, pretilachlor, pendimethalin, cycloxydim, tri-allate, metolachlor, diuron, alloxydim, prosulfuron, triflusulfuron-methyl, and acetochlor) in human blood is reported herein. Liquid-liquid extraction coupled with ultra-pressure liquid chromatography-tandem mass spectrometry was employed for the simultaneous analysis of all compounds in 15 min. Validation parameters were studied through the estimation of the limits of detection and quantification, calibration curves, sensitivity, spiked recovery and precision. The limits of detection ranged from 0.1 to 1.0 ng/mL. The limits of quantification ranged from 0.5 to 2.0 ng/mL. Good linearity was obtained for all compounds with R2> 0.99 in all cases. Furthermore, interday precision (< 15%) and intraday precision (< 15%) were shown to be satisfactory. Recoveries in spiked blood samples were evaluated, and acceptable values (88.0%~108.8%) were found. Finally, this method was successfully applied to the determination of fluazifop-P-butyl, isoproturon and acetochlor in blood samples from real forensic cases. These results suggest that this method is reliable for rapid forensic and clinical diagnosis. •A method for quantifying twenty herbicides in whole blood using UPLC–MS/MS was developed.•The method has been designed to be suitable for rapid forensic and clinical diagnosis.•Successfully applied in forensic routine analysis.

Redroot pigweed (Amaranthus retroflexus L.) is a troublesome dicot weed species widely distributed across China. A population of A. retroflexus that survived the recommended label rate of thifensulfuron-methyl was collected from the main soybean [Glycine max (L.) Merr.] production area in China. Whole-plant dose–response assays indicated that the resistant (R) population was highly resistant (61.80-fold) to thifensulfuron-methyl compared with the susceptible (S1 and S2) populations. In vitro acetolactate synthase (ALS) activity experiments showed that the thifensulfuron-methyl I50 value for the R population was 40.17 times higher than that for the S1 population. A preliminary malathion treatment study indicated that the R population might have cytochrome P450–mediated metabolic resistance. The R population exhibited a high level of cross-resistance to representative ALS herbicides (imazethapyr, flumetsulam, and bispyribac-sodium) and multiple resistance to the commonly used protoporphyrinogen oxidase (PPO)-inhibiting herbicides lactofen and fomesafen. Two common mutations, Trp-574-Leu in ALS and Arg-128-Gly in PPO2, were identified within the R population. This study identified possible enhanced metabolism of thifensulfuron-methyl coexisting with target-site mutations in both ALS and PPO2 in a multiple-resistant A. retroflexus population.