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The results of the study of toxicity level for the lamb's quarters (Chenopodium album L.) of well-known herbicides used in soybean crops as well as herbicides promising for soybean production in the Far East are presented. Lamb's quarters (Chenopodium album L.) is a highly noxious weed species that is widespread in the south of the region. Weediness monitoring conducted in 2006-2020 showed that this species was present in the Primorsky Territory on 63-100% of fields occupied by soybeans with an average growth density of 3-117 pcs/m2. In 2013-2020 in a series of experiments, conducted in the conditions of the vegetation house and on the experimental fields of the institute, the toxicity level for Common lamb's quarters was determined by 20 herbicides (based on 14 active substances) used in soybean crops. It was found that the control of this weed species is most effective when applying herbicides in the soil and treating plants with a height of up to 4-11 cm at the early stages of development - 1-3 pairs of leaves. Reliable suppression of lamb's quarters in experiments was provided by the soil (before sowing or before soybean seedlings) use of herbicides containing active substances metribuzin, imazetapir, trifluralin, pendimetalin and acetochlor. Among the active ingredients of the tested foliar herbicides, fomesafen, combinations of bentazone + acifluorfen and imazamox + chlorimuron-ethyl were the most toxic for lamb's quarters. It is recommended to use the following herbicidal preparations to control the spread of lamb's quarters: before sowing or sprouting of soybeans - Lazurit, Zenkor Ultra, Pivot, Proponit, Fabian; for processing vegetative plants - Flex, Galaksi Top, Concept, Classic Forte (Harmony Classic), Proponit.

Glyphosate-resistant (GR) Palmer amaranth is a troublesome weed that can emerge throughout the soybean growing season in Nebraska and several other regions of the United States. Late-emerging Palmer amaranth plants can produce seeds, thus replenishing the soil seedbank. The objectives of this study were to evaluate single or sequential applications of labeled POST herbicides such as acifluorfen, dicamba, a fomesafen and fluthiacet-methyl premix, glyphosate, and lactofen on GR Palmer amaranth control, density, biomass, seed production, and seed viability, as well as grain yield of dicamba- and glyphosate-resistant (DGR) soybean. Field experiments were conducted in a grower's field infested with GR Palmer amaranth near Carleton, NE, in 2018 and 2019, with no PRE herbicide applied. Acifluorfen, dicamba, a premix of fomesafen and fluthiacet-methyl, glyphosate, or lactofen were applied POST in single or sequential applications between the V4 and R6 soybean growth stages, with timings based on product labels. Dicamba applied at V4 or in sequential applications at V4 followed by R1 or R3 controlled GR Palmer amaranth 91% to 100% at soybean harvest, reduced Palmer amaranth density to as low as 2 or fewer plants m–2, reduced seed production to 557 to 2,911 seeds per female plant, and resulted in the highest soybean yield during both years of the study. Sequential applications of acifluorfen, fomesafen and fluthiacet premix, or lactofen were not as effective as dicamba for GR Palmer amaranth control; however, they reduced seed production similar to dicamba. On the basis of the results of this study, we conclude that dicamba was effective for controlling GR Palmer amaranth and reduced density, biomass, and seed production without DGR soybean injury. Herbicides evaluated in this study had no effect on Palmer amaranth seed viability. Nomenclature: Acifluorfen; dicamba; fluthiacet-methyl; fomesafen; glyphosate; lactofen; Palmer amaranth; Amaranthus palmeri S. Watson; soybean; Glycine max (L.) Merr.

A field experiment was conducted at Research cum Instructional Farm, IGKV, Raipur (C.G.) during rabi 2019-20 to know the influence of different herbicides on weed flora of berseem (Trifolium alexandrinum L.). The experiment was laid out in a Randomized Block Design with three replications of ten treatments viz. pendimethalin (PE) 1000 g/ha (T1), pendimethalin (EPoE) at 10 DAS 1000 g/ha (T2), oxyfluorfen (PE) 250 g/ha (T3) imazethapyr (PoE) 40 g/ha just after 1st cutting (T4), imazethapyr (PoE) 40 g/ha just after 2nd cutting (T5), imazethapyr (PoE) 40 g/ha just after 1st and 2nd cutting (T6), imazamox 35% + imazethapyr 35% (ready mix) (PoE) 70 g/ha just after 1st cutting (T7), imazamox 35% + imazethapyr 35% (ready mix) (PoE) 70 g/ha just after 2nd cutting (T8), sodium acifluorfen 16.5% + clodinafop-propargyl 8% (ready mix) (PoE) 187.5 g/ha just after 1st cutting (T9) and control (T10).The soil of experimental field was clayey in texture and slightly alkaline with (pH 7.4) in reaction. The amount of available N, P and K were low, medium and high respectively. Among these treatments, at 20 DAS and before 1st cutting of berseem the density and dry weight of weeds were found significantly lowest under the treatment oxyfluorfen 250 g/ha applied as PE (T3). However, before 2nd cutting and at harvest of berseem the density and dry weight of weeds were found significantly lowest under sodium acifluorfen 16.5% + clodinafop-propargyl 8% as PoE applied just after 1st cutting (T9).With regards to total weed density it was found at par with the PE application of oxyfluorfen 250 g/ha(T3). But it was also found phytotoxic effect on berseem crop up to 15-20 DAA, hence negative impact on the growth and yield of berseem plants was observed.

Six field trials were conducted over a four-year (2017-2020) period near Exeter and Ridgetown, Ontario to determine the efficacy of halosulfuron tankmixes applied postemergence to control broadleaf weeds in white bean. Halosulfuron caused up to 4% injury in white bean at 2 and 4 weeks after treatment (WAT). Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen caused 2% - 16% injury at 2 WAT and up to 3% injury at 4 WAT in white bean. The addition of halosulfuron to the aforementioned herbicides did not accentuate white bean injury. Reduced weed interference with the herbicides evaluated increased white been yield 50% - 90% compared to the weedy control; there was no difference in seed yield among herbicide treatments evaluated. At 4 WAT, halosulfuron at 25, 37.5 and 50 g ai ha-1 controlled velvetleaf 86%, 93% and 97%; redroot pigweed 83%, 85% and 89%; common ragweed 90%, 93% and 94%; common lambsquarters 27%, 28% and 36%; flower-of-an-hour 66%, 76% and 69%; and wild mustard 100%, 100% and 100%, respectively. Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen controlled velvetleaf 73%, 14%, 52%, 42% and 68%; redroot pigweed 40%, 91%, 85%, 75% and 80%; common ragweed 36%, 81%, 92%, 68% and 84%; common lambsquarters 87%, 39%, 48%, 60% and 76%; flower-of-an-hour 90%, 66%, 63%, 73% and 83%; and wild mustard 97%, 97%, 100%, 99% and 100%, respectively. Halosulfuron tankmixed with bentazon, acifluorfen, fomesafen, bentazon/acifluorfen or bentazon + fomesafen controlled velvetleaf 90%, 51%, 68%, 75% and 90%; redroot pigweed 80%, 99%, 95%, 92% and 91%; common ragweed up to 94%, 97%, 93%, 94% and 95%; common lambsquarters 74%, 62%, 43%, 62% and 66%; flower-of-an-hour 92%, 78%, 74%, 82% and 87%; and wild mustard 100%, 100%, 100%, 100% and 100%, respectively. Weed density and dry biomass followed the same trend. This study concludes that the optimal halosulfuron tankmix is broadleaf weed species specific for weed management in dry bean production.

Weeds, if not timely controlled, severely limit productivity of short-duration monsoon green gram. The aim of the present study was to identify a sustainable herbicidal management strategy in green gram-rapeseed rotation. Efficiency, phytotoxic effects in greengram and follow-up crop (rapeseed), yield, and economics of pre-emergence Pendimethalin and Pendimethalin + Imazethapyr and post-emergence [20 days after sowing (DAS)] Imazethapyr, Imazamox + Imazethapyr, and Acifluorfen sodium + Clodinafop propargyl were compared. Ready-mixes of two herbicide molecules were used. Among the herbicides, green gram treated with Imazamox + Imazethapyr (60 g a.i. ha−1) and Acifluorfen sodium + Clodinafop propargyl (187.5 g a.i. ha−1) showed significantly higher weed control efficiency of 81.3–85.1% and 90.5–92.9% on 30 and 55 DAS, respectively. In spite of initial herbicide induced oxidative stress and phytotoxicity, the crop treated with above-mentioned ready-mixes resumed normal growth within 15 days of herbicide application. They also recorded improvement in yields and net returns by 44.0–47.2% and 145.0–153.0%, respectively over weedy check. Detrimental residual effects on germination and yield were not observed in following rapeseed crop. These herbicide ready-mixes may be a promising weed management strategy for the monsoon green gram grown in the uplands of rice-dominated Indo-Gangetic plains.

The influence of acifluorfen and bentazon in the control of weeds in soybean was studied at the Students’ Research and Demonstration Farm, Kogi State University, Anyigba during the 2016 growing season. A low shattering and early maturity soybean cultivar with high oil content, TGX 1830-20E was used in this trial. The two herbicides were applied post-emergence at two rates each. Acifluorfen (5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoic acid) was applied at 0.2 and 0.4 kg a.i/ha;bentazon (3-(1-methylethyl(-(1H) -2, 1, 3 –benzothiadazin -4(3H) –one 2,2 – dioxide ) at 0.5 and 1.0 kg a.i/ha, while their mixtures, acifluorfen + asulam applied at 1.3 and 1.6 kg a.i /ha and bentazon + asulam at 1.4 and 1.7 kg a.i/ha. Parameters measured included phytotoxicity of the herbicides to soybean, weed control effectiveness, plant height, number of pods/plant, number of seeds/plant, seed weight /plant and total grain yield (kg/ha). Results showed that weed control effectiveness was higher and the crop performance most especially in terms of total grain yield (Kg/ha) was better in plots that received mixture formulation of acifluorfen + asulam and bentazon + asulam than where acifluorfen or bentazon was applied as single formulation irrespective of rates. The highest grain yield (1066 kg/ha) obtained from plots to which 1.6 kg a.i/ha of acifluorfen + asulam was applied compared favourably with that realized from the hoe weeded plots (1044.5 kg a.i/ha). Abysmally low grain yield was obtained from the weedy check.

Field studies were conducted in 2017 and 2018 in Arkansas to evaluate the injury caused by herbicides on soybean canopy formation and yield. Fomesafen, acifluorfen, S-metolachlor + fomesafen, and S-metolachlor + fomesafen + chlorimuron alone and in combination with glufosinate were applied to glufosinate-resistant soybean at the V2 growth stage. Soybean injury resulting from these labeled herbicide treatments ranged from 9% to 25% at 2 wk after application. This level of injury resulted in a 4-, 5-, 6-, and 6-d delay in soybean reaching 80% groundcover following fomesafen, acifluorfen, S-metolachlor + fomesafen, and S-metolachlor + fomesafen + chlorimuron, respectively. There was a 2-d delay in soybean reaching a canopy volume of 15,000 cm3 following each of the four herbicide treatments. The addition of glufosinate to the herbicide applications resulted in longer delays in canopy formation with every herbicide treatment except glufosinate + fomesafen. Fomesafen, acifluorfen, S-metolachlor + fomesafen, and S-metolachlor + fomesafen + chlorimuron, each applied with glufosinate, delayed soybean from reaching 80% groundcover by 2, 7, 8, and 9 d, respectively, and delayed the number of days for soybean to reach a canopy volume of 15,000 cm3 by 2, 3, 2, and 2 d, respectively. No yield loss occurred with any herbicide application. A delay in percent groundcover in soybean allows sunlight to reach the soil surface for longer periods throughout the growing season, possibly promoting late-season weed germination and the need for an additional POST herbicide application.

Pigeonpea has great potential as a profitable summer legume rotational crop in cereal farming systems of subtropical Australia. Pigeonpea requires season-long weed control, but options for controlling broadleaf weeds in pigeonpea with POST herbicides are limited. The objective of this study was to evaluate the performance of different herbicides (PRE: pendimethalin; POST: acifluorfen, bentazon, and imazapic) applied singly or in sequence for horse purslane control in pigeonpea and their impact on pigeonpea yield. Field experiments were conducted in 2017 and 2018 at Gatton, Australia. Pendimethalin applied PRE at 1.14 kg ai ha−1 reduced horse purslane biomass by 87% and 92% and produced 32% and 105% higher grain yield compared with the nontreated control in 2017 and 2018, respectively. Imazapic applied POST at 0.10 kg ai ha−1 reduced horse purslane biomass by 79% and 82% and increased grain yield by 60% and 88% compared with the nontreated control in 2017 and 2018, respectively. Acifluorfen applied POST (0.34 and 0.42 kg ai ha−1) caused 16% to 48% injury to pigeonpea at 45 d after treatment. Control of horse purslane ranged from 87% to 92% (biomass reduction) with pendimethalin applied PRE at 1.14 kg ai ha−1 and was comparable with pendimethalin applied PRE at 0.91 kg ai ha−1 in the sequential application, and imazapic at 0.08 kg ai ha−1 or bentazon at 0.96 kg ai ha−1. The study findings suggest if farmers miss the PRE application of pendimethalin or are unable to achieve season-long weed control, POST application of imazapic is an alternate. This research provided herbicide options for control of horse purslane in pigeonpea that could be used in rotations for reducing the selection pressure of weeds.

Acifluorfen is a nonsystemic PPO-inhibiting herbicide commonly used for POST Palmer amaranth control in soybean, peanut, and rice across the southern United States. Concerns have been raised regarding herbicide selection pressure and particle drift, increasing the need for application practices that optimize herbicide efficacy while mitigating spray drift. Field research was conducted in 2016, 2017, and 2018 in Mississippi and Nebraska to evaluate the influence of a range of spray droplet sizes [150 µm (Fine) to 900 µm (Ultra Coarse)], using acifluorfen to create a novel Palmer amaranth management recommendation using pulse width modulation (PWM) technology. A pooled site-year generalized additive model (GAM) analysis suggested that 150-µm (Fine) droplets should be used to obtain the greatest Palmer amaranth control and dry biomass reduction. Nevertheless, GAM models indicated that only 7.2% of the variability observed in Palmer amaranth control was due to differences in spray droplet size. Therefore, location-specific GAM analyses were performed to account for geographical differences to increase the accuracy of prediction models. GAM models suggested that 250-µm (Medium) droplets optimize acifluorfen efficacy on Palmer amaranth in Dundee, MS, and 310-µm (Medium) droplets could sustain 90% of maximum weed control. Specific models for Beaver City, NE, indicated that 150-µm (Fine) droplets provide maximum Palmer amaranth control, and 340-µm (Medium) droplets could maintain 90% of greatest weed control. For Robinsonville, MS, optimal Palmer amaranth control could be obtained with 370-µm (Coarse) droplets, and 90% maximum control could be sustained with 680 µm (Ultra Coarse) droplets. Differences in optimal droplet size across location could be a result of convoluted interactions between droplet size, weather conditions, population density, plant morphology, and soil fertility levels. Future research should adopt a holistic approach to identify and investigate the influence of environmental and application parameters to optimize droplet size recommendations.Nomenclature: Acifluorfen; Palmer amaranth, Amaranthus palmeri S. Wats., AMAPA; peanut, Arachis hypogaea L.; rice, Oryza sativa L.; soybean, Glycine max (L.) Merr

Cover crops can provide many benefits to peanut and cotton crops planted in rotation including suppressing weeds, conserving soil moisture after termination, increasing soil organic matter, and reducing soil erosion. However, herbicide carryover can affect cover crop establishment. The objective of this study was to investigate the responses of 6 cover crops (daikon radish, cereal rye, oat, crimson clover, winter wheat, and common vetch) to 12 soil residual herbicides. A multiyear (2016–2018), multilocation study was conducted in Macon and Henry counties, Alabama. Herbicide treatments included S-metolachlor, acetochlor, pyroxasulfone, diclosulam, imazapic, chlorimuron-ethyl, bentazon plus acifluorfen, pyrithiobac-sodium, trifloxysulfuron-sodium, diuron, prometryn, and flumioxazin, each applied at 10% of the full-labeled rate. At 42 to 52 and 145 to 149 d after planting (DAP), cover crop plant heights and stand counts were evaluated, as was biomass at 145 to 149 DAP. Treatments varied from year to year but not locations. In 2016, significant stand reductions (P ≤ 0.10) of 36% to 43% in rye and 44% to 75% in wheat were observed at 48 to 52 DAP for S-metolachlor, acetochlor, pyroxasulfone, imazapic, and bentazon plus acifluorfen compared with nontreated plants. Vetch had stand reductions ranging from 14% to 80% for all treatments 50 DAP except for plants treated with prometryn. S-metolachlor, pyroxasulfone, and acetochlor reduced stands of rye, wheat, and vetch more than any other herbicides. In 2017, at 147 to 149 DAP, clover stands were reduced by 29% with diclosulam and by 38% with trifloxysulfuron-sodium. Similarly, radish stands were reduced by 64% with diclosulam treatment. No significant biomass reductions were observed for any cover crop species either year. Oat showed the most tolerance with no treatments reducing any growth parameters either year. Although initial injury and stunting may occur, biomass at termination of cover crops were not affected by herbicide residues evaluated in this study.Nomenclature: Acetochlor; acifluorfen; bentazon; chlorimuron-ethyl; diclosulam; diuron; flumioxazin; imazapic; prometryn; pyroxasulfone; pyrithiobac-sodium; S-metolachlor; trifloxysulfuron-sodium; cereal rye; Secale cereal L.; common vetch; Vicia villosa L.; cotton, Gossypium hirsutum L.; crimson clover, Trifolium incarnatum L.; daikon radish, Raphanus sativis L.; oat, Avena sativa L.; peanut, Arachis hypogaea L.; winter wheat, Triticum aestivum L.

A limited number of postemergence (POST) herbicides are available for weed management in azuki bean production in Ontario. A total of three field trials were conducted during 2017 to 2019 at the Huron Research Station, University of Guelph, Exeter, Ontario, Canada to evaluate the efficacy of various postemergence (POST) herbicides for weed control in azuki bean. Fomesafen, acifluorfen and acifluorfen + Assist® caused up to 6% crop injury and weed interference reduced azuki bean yield up to 42%. Bentazon, bentazon Forte, bentazon/acifluorfen, bentazon + fomesafen + Assist®, bentazon + fomesafen + Turbocharge® and bentazon Forte + fomesafen caused up to 16% injury and weed interference reduced azuki bean yield up to 53%. Fomesafen, acifluorfen, acifluorfen + Assist®, bentazon, bentazon Forte, bentazon/acifluorfen, bentazon + fomesafen + Assist®, bentazon + fomesafen + Turbocharge® and bentazon Forte + fomesafen provided 36% to 88% control of redroot pigweed (Amaranthus retroflexus L.), common ragweed (Ambrosia artemesiifolia L.), and common lambsquarters (Chenopodium album L.). Fomesafen, acifluorfen + Assist® and acifluorfen provided 59% to 83% control of flower-of-an-hour (Hibiscus trionum L.), but bentazon, bentazon Forte, bentazon/acifluorfen, bentazon + fomesafen + Assist®, bentazon + fomesafen + Turbocharge® and bentazon Forte + fomesafen provided 78% to 99% control of H. trionum. All POST herbicides evaluated provide 99% to 100% control of wild mustard (Sinapis arvensis L.) in azuki bean. Based on these results, none of the POST herbicide evaluated that included bentazon can be used safely for the control of annual broadleaved weeds in azuki bean under Ontario environmental conditions.

Extensive acceptance of glyphosate-resistant (GR) row crops coupled with the simultaneous increase in glyphosate usage has sped the evolution of glyphosate resistance in economically important weeds. GR Amaranthus palmeri populations are widespread across the state with some exhibiting multiple resistance to acetolactate synthase (ALS) inhibiting herbicides such as pyrithiobac. A GR and ALS inhibitor-resistant accession was also resistant to the protoporphyrinogen oxidase (PPO) inhibiting herbicide fomesafen. The PPO inhibitor resistance profile and multiple herbicide resistance mechanisms in this accession were investigated. In addition to fomesafen, resistance to postemergence applications of acifluorfen, lactofen, carfentrazone, and sulfentrazone was confirmed. There was no resistance to preemergence application of fomesafen, flumioxazin, or oxyfluorfen. Molecular analysis of the ALS gene indicated the presence of point mutations leading to single nucleotide substitutions at codons 197, 377, 574, and 653, resulting in proline-to-serine, arginine-to-glutamine, tryptophan-to-leucine, and serine-to-asparagine replacements, respectively. The resistant accession contained up to 87-fold more copies of the EPSPS gene compared to a susceptible accession. A mutation leading to a deletion of glycine at codon 210 (ΔG210) of PPO2 gene was also detected. These results indicate that the mechanism of resistance in the Palmer amaranth accession is target-site based, i.e., altered target site for ALS and PPO inhibitor resistance and gene amplification for glyphosate resistance.

Herbicide applications performed with pulse width modulation (PWM) sprayers to deliver specific spray droplet sizes could maintain product efficacy, minimize potential off-target movement, and increase flexibility in field operations. Given the continuous expansion of herbicide-resistant Palmer amaranth populations across the southern and midwestern United States, efficacious and cost-effective means of application are needed to maximize Palmer amaranth control. Experiments were conducted in two locations in Mississippi (2016, 2017, and 2018) and one location in Nebraska (2016 and 2017) for a total of 7 site-years. The objective of this study was to evaluate the influence of a range of spray droplet sizes [150 (Fine) to 900 µm (Ultra Coarse)] on lactofen and acifluorfen efficacy for Palmer amaranth control. The results of this research indicated that spray droplet size did not influence lactofen efficacy on Palmer amaranth. Palmer amaranth control and percent dry-biomass reduction remained consistent with lactofen applied within the aforementioned droplet size range. Therefore, larger spray droplets should be used as part of a drift mitigation approach. In contrast, acifluorfen application with 300-µm (Medium) spray droplets provided the greatest Palmer amaranth control. Although percent biomass reduction was numerically greater with 300-µm (Medium) droplets, results did not differ with respect to spray droplet size, possibly as a result of initial plant injury, causing weight loss, followed by regrowth. Overall, 900-µm (Ultra Coarse) droplets could be used effectively without compromising lactofen efficacy on Palmer amaranth, and 300-µm (Medium) droplets should be used to achieve maximum Palmer amaranth control with acifluorfen.Nomenclature: Acifluorfen; lactofen; Palmer amaranth, Amaranthus palmeri S. Wats. AMAPA

A redroot pigweed (Amaranthus retroflexus L.) population (HN-02) collected from Nenjiang County, Heilongjiang Province, exhibited multiple resistance to fomesafen and nicosulfuron. The purposes of this study were to characterize the herbicide resistance status of an HN-02 population for both acetolactate synthase (ALS) and protoporphyrinogen oxidase (PPO) inhibitors and the response to other herbicides and to investigate the target site-based mechanism governing fomesafen and nicosulfuron resistance. Three mutations, Ala-205-Val and Trp-574-Leu mutations in the ALS gene and an Arg-128-Gly mutation in the PPX2 gene, were identified in individual resistant plants. An HN-02F1-1 subpopulation homozygous for the Ala-205-Val and Arg-128-Gly mutations was generated, and whole-plant experiments confirmed multiple resistance to PPO inhibitors (fomesafen, fluoroglycofen-ethyl, and acifluorfen) and ALS inhibitors (imidazolinones [IMI], sulfonylureas [SU], and triazolopyrimidines [TP]) in the HN-02F1-1 plants, which presented resistance index values ranging from 8.3 to 110; however, these plants were sensitive to flumioxazin, fluroxypyr-meptyl, and 2,4-D butylate. In vitro ALS enzyme activity assays revealed that, compared with ALS from susceptible plants, ALS from the HN-02F1-1 plants was 15-, 28- and 320-fold resistant to flumetsulam, nicosulfuron, and imazethapyr, respectively. This study confirms the first case of multiple resistance to PPO and ALS inhibitors in A. retroflexus and determines that the target-site resistance mechanism was produced by Ala-205-Val and Arg-128-Gly mutations in the ALS gene and PPX2 gene, respectively. In particular, the Ala-205-Val mutation was found to endow resistance to three classes of ALS inhibitors: TP, SU, and IMI.

Photosensitizers need to be activated by external light to achieve phototherapy. However, unsatisfactory tissue penetration of light and uncontrollable light intensity limit their application. To o...

Studies to evaluate the effect of application time of day (TOD) and protoporphyrinogen IX oxidase (PPO)-inhibiting herbicide–resistant Palmer amaranth on the efficacy of commonly used herbicides was conducted in Tennessee in 2017 and 2018. Treatments of fomesafen, lactofen, acifluorfen, paraquat, glufosinate, glufosinate plus fomesafen, paraquat plus fomesafen, and paraquat plus metribuzin were applied to PPO-resistant (PPO-R) and PPO-susceptible (PPO-S) Palmer amaranth at sunrise and midday. Control of Palmer amaranth with acifluorfen, glufosinate, and glufosinate plus fomesafen was greater with the midday application. However, control of Palmer amaranth with paraquat-based treatments was greater with the sunrise application. TOD effects on PPO-inhibiting herbicides and paraquat-based treatments were more prominent for the PPO-R Palmer amaranth biotype. The TOD effect observed when applying glufosinate in early morning hours on PPO-S Palmer amaranth can be minimized by adding fomesafen to the tank mix. However, this strategy did not provide consistent performance on PPO-R Palmer amaranth. The percentages of living Palmer amaranth plants and control were greater when paraquat plus metribuzin was applied to both biotypes. These results highlight the necessity of at least two effective herbicide sites of action for POST applications intended for controlling PPO-R Palmer amaranth. In addition, the timing of herbicide applications can affect their activity in both PPO-R and PPO-S Palmer amaranth populations.Nomenclature: acifluorfen; fomesafen; glufosinate; lactofen; metribuzin; paraquat; Palmer amaranth; Amaranthus palmeri S. Watson

A waterhemp [Amaranthus tuberculatus(Moq.) J. D. Sauer] biotype (designated as “NER”) collected from a soybean [Glycine max(L.) Merr.] production field in eastern Nebraska survived the POST application of fomesafen at the labeled rate. The objectives of this study were to (1) quantify the level of resistance to protoporphyrinogen oxidase (PPO) inhibitors (acifluorfen, fomesafen, and lactofen) applied POST, (2) determine the mechanism of PPO-inhibitor resistance in the NER biotype, (3) determine whether NER possessed multiple resistance to acetolactate synthase (ALS)-, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS)-, and photosystem II (PSII)-inhibiting herbicides, and (4) control NER with POST soybean herbicides. A whole-plant dose–response bioassay revealed that the NER biotype was 4- to 6-fold resistant to PPO-inhibiting herbicides depending on the known susceptible biotype (S1 or S2) used for comparison. A Kompetitive Allele Specific PCR (KASP™) assay was developed and performed for rapid and robust detection of the ΔG210 mutation (deletion of a codon) in thePPX2Lgene. All samples of the NER biotype tested positive for the ΔG210 mutation. Dose–response bioassays confirmed that the NER biotype was resistant to three additional herbicide sites of action. Chlorimuron and imazethapyr, both ALS inhibitors, applied at 32X the labeled rate resulted in Amaranthus tuberculatusis the first confirmed weed species in Nebraska to evolve resistance to four distinct herbicide sites of action, leaving no POST herbicide choice for effective control in glyphosate-resistant and conventional (non-transgenic) soybean.

Palmer amaranth is one of the most problematic weeds in cropping systems of North America, especially in midsouthern United States, because of its competitive ability and propensity to evolve resistance to several herbicide sites of action. Previously, we confirmed and characterized the first case of nontarget site resistance (NTSR) to fomesafen in a Palmer amaranth accession from Randolph County, AR (RCA). The primary basis of the present study was to evaluate the cross- and multiple-resistance profile of the RCA accession. The fomesafen dose-response assay in the presence of malathion revealed a lower level of RCA resistance when compared with fomesafen alone. The resistance index of the RCA accession, based on 50% biomass reduction, ranged from 63-fold (fomesafen alone) to 22-fold (malathion plus fomesafen), when compared with a 2007 susceptible, and 476-fold and 167-fold, respectively, relative to a 1986 susceptible check. The RCA accession was resistant to other protoporphyrinogen oxidase (PPO) inhibitors (i.e., flumioxazin, acifluorfen, saflufenacil) as well as the 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor tembotrione and acetolactate synthase (ALS) inhibitor pyrithiobac sodium. Sequencing of the ALS gene revealed no point mutations, indicating that a target-site mechanism is not involved in conferring ALS-inhibitor resistance in the RCA accession. Of the three PPO-inhibiting herbicides tested in combination with the malathion, saflufenacil resulted in the greatest biomass reduction (80%; P < 0.05) and lowest survival rate (23%; P < 0.05) relative to nontreated plants. The application of cytochrome P450 or glutathione S-transferase inhibitors with fomesafen did not lead to any adverse effects on soybean, suggesting a possible role for these compounds for management of NTSR under field conditions. These results shed light on the relative unpredictability of NTSR in conferring herbicide cross- and multiple resistance in Palmer amaranth. Nomenclature: Acifluorfen; flumioxazin; fomesafen; malathion; pyrithiobac sodium; saflufenacil; tembotrione; Palmer amaranth, Amaranthus palmeri (S.) Wats.; soybean, Glycine max (L.) Merr.

The development of a linuron-free weed management strategy for carrot production is essential as a result of the herbicide reevaluation programs launched by the Pest Management Regulatory Agency in Canada for herbicides registered before 1995 and the discovery of linuron-resistant pigweed species in Ontario. Field trials were conducted in one of Ontario’s main carrot-growing regions on high organic soils in 2016 and 2017. Pigweed species seedlings were effectively controlled with PRE treatments of prometryn, pendimethalin, S-metolachlor, or glufosinate. POST treatments of pyroxasulfone and metribuzin followed by predetermined biologically effective dose (≥90% control of pigweed seedlings) of acifluorfen, oxyfluorfen, fluthiacet-methyl, and fomesafen achieved excellent crop selectivity and commercially acceptable pigweed species seedling control under field conditions. Carfentrazone-ethyl or fomesafen applied PRE severely reduced seedling emergence and yield in the wet growing season of 2017. This study demonstrated clearly that an alternative linuron-free strategy can be developed for carrots. The strategy of exploring the potential to use the biologically effective dose of selected herbicides to achieve crop selectivity and control of pigweed species seedlings was verified.

Smellmelon is an invasive weed in the Golestan and Mazandran provinces of Iran. In a series of experiments, germination of freshly harvested seeds, cardinal temperatures, plant burial depth, and distribution and chemical control of smellmelon were evaluated to assist us in developing a management program to help growers manage this weed more effectively. The optimal seed germination temperature was estimated at 32.7 C by a two-piece segmented model. Mature fresh seeds of smellmelon exhibited no dormancy, whereas mucilage of the seed negatively affected germination. The greatest seed sowing depth from which seedlings emerged was 5 cm. Geographical distribution of smellmelon occurred up to an elevation of 350m above sea level, whereas the density of smellmelon decreased at elevations higher than 151 m. Imazethapyr reduced plant growth and the reproductive capacity of smellmelon. Germination of seed from smellmelon plants treated with imazethapyr was significantly reduced compared with seed treated with bentazon or bentazon plus acifluorfen. A combination of tillage of deeper than 5 cm, early planting time, and the use of imazethapyr can reduce smellmelon competition in various field crops.Nomenclature: Acifluorfen; bentazon; imazethapyr; smellmelon; Cucumis melo L. var. agrestis Naudin

Paraquat postemergence (POST) applied is often used to control broadleaf and grass weed species in peanut in the Southeast US. The objective of this study was to determine the effects of POST herbicide tank-mixtures including paraquat on vegetation, yield, and grade for runner-type peanut cultivars under irrigated and non-irrigated conditions. Two separate experiments (irrigated and non-irrigated) were conducted in 2016 and 2017 in Ty Ty and Plains Georgia. Georgia-06G, Georgia-14N, TUFRunner™ ‘511’, and FloRun™ ‘157’ cultivars were evaluated. Herbicide tank-mixtures included paraquat, paraquat plus acifluorfen plus bentazon, paraquat plus acifluorfen plus bentazon plus S-metolachlor, and paraquat plus acifluorfen plus bentazon plus acetochlor. Leaf burn, stunting injury, yield, and grade were evaluated. There were no interactions between herbicide and cultivar for all variables. Paraquat alone resulted in significantly greater foliar injury (3 DAT) than the other herbicide treatments for the irrigated (34 to 16%) and non-irrigated (28 to 15%) studies. Stunting for paraquat alone was noted at 15 and 35% for irrigated and non-irrigated, respectively. Similarly, in both studies, Georgia-06G and TUFRunner™ ‘511’ yielded 10 to 12% greater than Georgia-14N and FloRun™ ‘157’. Overall, the herbicide tank-mixtures did not have a negative effect on yield. With no interactions observed, these herbicide treatments can be used in conjunction with the given runner-type peanut cultivars in either irrigated or non-irrigated conditions without concern for excessive injury or decline in yield or grade.

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&deg, 49&prime, E131&deg, 36&prime, ). No herbicide application resulted in significant soybean yield loss, 0.03&ndash, 0.3 t ha&minus, 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&minus, 1, respectively, provided with 724.5 US$ and 1155.6 US$ ha&minus, 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.

In this work, 12 novel herbicidal ionic liquids (HILs) based on acifluorfen were prepared by pairing with the fluorescent hydrazides or different alkyl chains for increasing activities and reducing negative impacts on the aquatic environment. The results showed that the fluorescence of coumarin hydrazide in the HILs was applied as the internal and supplementary light source to meet the requirement of light wavelength range of acifluorfen, which improved the phytotoxicity of acifluorfen to weeds by enhancing singlet oxygen generation with increased sunlight utilization. The herbicidal activities of HILs were related positively with the length of chain of cation under high light intensity and depended mainly on the fluorescence characteristic of the cation under low light intensity, and the double salt IL forms of acifluorfen containing coumarin hydrazide and n-hexadecyltrimethylammonium had enhanced efficacies against broadleaf weeds in the field. Compared with acifluorfen sodium, HILs had lower water solubility, better surface activity, weaker mobility in soils, and higher decomposition temperature. These results demonstrated that HILs containing different cations provided a wider scope for fine-tuning of the physicochemical and biological properties of herbicides and established a promising way for the development of environmentally friendly herbicidal formulations.

The extensive use of the diphenyl ether herbicide lactofen in recent years has caused serious environmental problems. Therefore, detoxification and elimination of lactofen from the environment are urgently required. In this study, the lactofen-degrading strain Bacillus sp. YS-1 was isolated, which achieved a 97.6% degradation rate of 50 mg/L lactofen within 15 h. The ester bond of lactofen was hydrolyzed, which generated acifluorfen, and then, the nitro group was reduced to the amino group, which generated aminoacifluorfen. Finally, the amino group was acetylated, which formed acetylated aminoacifluorfen, a novel end product in the degradation of lactofen. The toxicity of acetylated aminoacifluorfen to the root and seedling growth of cucumber and sorghum was significantly decreased compared with that of lactofen. The two esterase genes rhoE and rapE, encoding two esterases responsible for lactofen hydrolysis to acifluorfen, were cloned and expressed. The amino acid sequences encoded by rhoE and rapE were 27.78% and 88.21% identical with known esterases, respectively. The optimum temperatures for RhoE and RapE degradation of lactofen were 35 °C and 25 °C, respectively, and both esterases displayed maximal activity at pH 8.0. Both RhoE and RapE prioritized the degradation of (S)-(+)-lactofen, (S)-(−)-quizalofop-ethyl, and (S)-(−)-diclofop-methyl. This study provided the resources of bacterial strain and hydrolyzing enzyme for the removal of lactofen from the environment and the bioremediation of herbicide-contaminated soil.

We conducted biochemical and physiological experiments to investigate the mode of action of tiafenacil (Terrad'or™), a new protoporphyrinogen IX oxidase (PPO)-inhibiting pyrimidinedione herbicide. Analysis of the half-maximal inhibitory concentration (IC50) against recombinant PPO enzymes from various plant species, including amaranth (Amaranthus tuberculatus), soybean (Glycine max), arabidopsis (Arabidopsis thaliana), and rapeseed (Brassica napus), showed that tiafenacil had an IC50 of 22 to 28 nM, similar to the pyrimidinedione herbicides butafenacil and saflufenacil and the N-phenylphthalimide herbicide flumioxazin. By contrast, tiafenacil exhibited 3- to 134-fold lower IC50 values than the diphenyl ether herbicides fomesafen, oxyfluorfen, and acifluorfen. Tiafenacil is non-selective and is herbicidal to both dicots and monocots, such as the weeds velvetleaf (Abutilon theophrasti), amaranth, and barnyardgrass (Echinochloa crus-galli) as well as the crops soybean, rapeseed, rice (Oryza sativa), and maize (Zea mays) at concentrations ranging from 1 to 50 μM. Treatment of plant tissue with tiafenacil in darkness resulted in the accumulation of protoporphyrin IX. Subsequent exposure to light increased the content of malondialdehyde and significantly decreased the Fv/Fm values of chlorophyll fluorescence. The results suggest that tiafenacil is a new PPO-inhibiting pyrimidinedione herbicide.

Florpyrauxifen-benzyl is a new herbicide being developed for rice. Research is needed to understand its spectrum of control and optimal tank-mix partners. Multiple greenhouse and field experiments were conducted to evaluate florpyrauxifen-benzyl efficacy and tank-mix compatibility. In greenhouse experiments, florpyrauxifen-benzyl at 30 g ai ha-1 provided ≥75% control of all weed species evaluated (broadleaf signalgrass, barnyardgrass, Amazon sprangletop, large crabgrass, northern jointvetch, hemp sesbania, pitted morningglory, Palmer amaranth, yellow nutsedge, rice flatsedge, smallflower umbrellasedge), and control was similar to or better than other herbicide options currently available in rice. Barnyardgrass was controlled 97% with florpyrauxifen-benzyl at 30 g ha-1, ultimately reducing height (86%) and aboveground biomass (84%). In these field studies at 30 g ha-1, no antagonism was observed when florpyrauxifen-benzyl was tank-mixed with contact (acifluorfen, bentazon, carfentrazone, propanil, and saflufenacil) or systemic (2,4-D, bispyribac, cyhalofop, fenoxaprop, halosulfuron, imazethapyr, penoxsulam, quinclorac, and triclopyr) rice herbicides. Although not every tank-mix or weed species was evaluated, the lack of antagonistic interactions herein highlights the flexibility and versatility of this new herbicide. Once florpyrauxifen-benzyl becomes commercially available, it will be beneficial to tank-mix this new herbicide with others without sacrificing efficacy, so as to apply multiple sites of action together and thus lessen the risk for evolution of herbicide resistance.Nomenclature: Acifluorfen; bentazon; bispyribac; carfentrazone; florpyrauxifen-benzyl (benzyl 4-amino-3-chloro-6-(4-chloro-2-fluoro-3- methoxyphenyl)-5-fluoropyridine-2- carboxylate); cyhalofop; fenoxaprop; halosulfuron; imazethapyr; penoxsulam; propanil; quinclorac; saflufenacil; 2; 4-D; triclopyr; Amazon sprangletop, Leptochloa panicoides (J. Presl) Hitchc.; barnyardgrass, Echinochloa crus-galli L. Beauv.; broadleaf signalgrass, Urochloa platyphylla (Munro ex C. Wright) R.D. Webster; hemp sesbania, Sesbania hederacea (P. Mill.) McVaugh; large crabgrass, Digitaria sanguinalis L. Scop; northern jointvetch, Aeschynomene virginica L. Britton, Sterns & Poggenb.; Palmer amaranth, Amaranthus palmeri (S.) Wats.; pitted morningglory, Ipomoea lacunosa L.; rice flatsedge, Cyperus iria L.; smallflower umbrellasedge, Cyperus difformis L.; yellow nutsedge, Cyperus esculentus L.; rice, Oryza sativa L.

Glyphosate-resistant (GR) common waterhemp (CW) is a localized weed in Ontario and one of the most problematic weeds in the US Corn Belt. First confirmed in Ontario in 2014, GR CW has now been confirmed in forty fields in three counties in Ontario as of 2015. Historically, the primary POST herbicides used for the control of CW in soybean were glyphosate, acifluorfen and fomesafen, but resistance to all three has been confirmed in many US states. Research was conducted in 2015 and 2016 to determine the control of GR CW with some of the new herbicide-resistant soybean technologies including glufosinate (LibertyLink), 2,4-D and glyphosate (Enlist), and isoxaflutole, mesotrione, and glufosinate (HPPD-resistant). Glyphosate-resistant CW was controlled (≥90%) all season with a two-pass weed control system across all herbicide-resistant soybean technologies evaluated. The two-pass weed control system in this research is defined as a PRE herbicide followed by a POST herbicide. At 12 WAA, the two-pass programs in LibertyLink, Enlist, and HPPD-resistant systems controlled GR CW up to 98, 98, and 92%, respectively, and reduced GR CW densities to 0 to 2% of the weedy control at 4 WAA. The two-pass programs provided greater GR CW control than PRE or POST herbicides alone. This study found that the use of two-pass weed control programs in glufosinate-resistant, glyphosate DMA/2,4-D choline-resistant and HPPD-resistant soybean can provide excellent control of GR CW, and can be valuable tools to reduce the selection intensity for herbicide-resistant weeds. Through the rotational use of different technologies, growers may be able to better manage their weed populations in reducing the risk of resistance when compared to the use of one herbicide repeatedly.

Chickpea producers currently have no POST applied herbicides labeled for broadleaf weed control and rely heavily on PRE herbicides to manage weeds. Severe crop losses from broadleaf weed competition and harvest losses from weeds impeding harvest can occur when PRE herbicides perform poorly. Chickpea tolerance to POST applications of acifluorfen at 0.42 kg ai ha-1 and fomesafen at 0.28 kg ai ha-1 was tested at two sites in 2015. In 2016, both herbicides were tested on chickpeas when applied alone and in combination with pyridate at three sites. Acifluorfen and fomesafen injured chickpeas from 8 to 25% at 1 week after treatment (WAT) and 3 to 8% at 4 WAT in 2015 and from 16 to 40% at 1 WAT and 2 to 36% at 4 WAT in 2016. Pyridate applied POST at 1.00 kg ai ha-1 did not injure chickpeas or reduce yields. When pyridate was tank mixed with either acifluorfen or fomesafen, chickpea injury increased, but chickpeas recovered and yielded similar to nontreated checks or pyridate-treated plots. A low rate of metribuzin at 0.06 kg ai ha-1 tank mixed with pyridate had little impact on chickpea injury or weed control. In 2015, Russian thistle was controlled 100% by acifluorfen and fomesafen at Prosser at 28 DAT and both herbicides controlled the weed only 63% at Wilbur at 25 DAT. In 2016, all herbicide treatments reduced broadleaf weed densities equally ranging from 95 to 100% at Paterson, 50 to 100% at Prosser, and 78 to 98% at Wilbur. Chickpea yield was similar among POST herbicide treatments in all site-years. Acifluorfen, fomesafen, and pyridate have potential to improve control of susceptible broadleaf weeds that escape PRE herbicides chickpea production, but the potential for crop injury with acifluorfen and fomesafen warrant further evaluation.

Chickpea faces an extended period of critical weed competition due to its slow initial growth and requires sequential herbicide application to obtain maximum yield. However, no post-emergence herbicides are available especially for controlling broad-leaved weeds. Post-emergence herbicides like topramezone, imazethapyr + imazamox and clodinafop-propargyl + Na-acifluorfen for their phytotoxicity and bio-efficacy was evaluated in chickpea. Phytotoxicity of imazethapyr + imazamox 60 g a.i./ha on chickpea was prolonged and crop recovery was poor. On the contrary, phytotoxicity on crop due to topramezone 40 and 60 g a.i./ha and clodinafop-propargyl + Na-acifluorfen 500 g a.i./ha was minimal (rating 6). Significantly lower (P ≤ 0.05) weed population by 66.2 and 54% were recorded in topramezone 60 g a.i./ha and clodinafop-propargyl + Na-acifluorfen 500 g a.i./ha, respectively, over unweeded control at 65 DAS, besides significant reduction in dry weight of weeds. The WCE and WCI were higher in topramezone 60 g a.i./ha (71.6%) at 65 DAS and in clodinafop-propargyl + Na-acifluorfen 500 g a.i./ha at 95 DAS, respectively. Moreover, these had an edge over two hand weeding and quizalofop ethyl 50 g a.i./ha (recommended post-emergence herbicide) in chickpea. Treatments topramezone 40 g a.i./ha and clodinafop-propargyl + Na-acifluorfen 500 g a.i./ha recorded significantly (P ≤ 0.05) higher grain yield by 26.4 and 20.1% over quizalofop ethyl 50 g a.i./ha. Therefore, topramezone and clodinafop propargyl + Na-acifluorfen could be an option for controlling the diversified weed flora particularly broad-leaved weeds like Chenopodium album, Melilotus alba, Medicago denticulata and others in chickpea.

Carinata is a new biofuel crop that was recently introduced in the southeastern USA as a winter crop. This crop is competitive after canopy closure, but there is a need for weed control options at earlier growth stages. Field experiments were conducted from 2014 to 2016 to determine the safety of several PRE and POST herbicides in carinata. Pendimethalin at 1080 g ai ha−1 applied preplant incorporated (PPI) and PRE caused no carinata injury, or plant density and yield reductions. S-metolachlor was also safe at 694, 1070, 1390, and 2780 g ai ha−1 applied at PRE, 3 d after planting (DAP) and at the 2- to 6-leaf stage. Flumioxazin at 72 g ai ha−1 applied PRE was highly injurious on carinata preventing its establishment. Among the POST herbicides evaluated, clopyralid at 210 g ae ha1 and clethodim at 136 g ai ha−1 caused minor injury to carinata but did not reduce yield compared to the nontreated control. Acifluorfen at 420 g ai ha−1, bentazon at 840 g ai ha−1, and carfentrazone at 18 g ai ha−1 applied POST to carinata caused 75 to 100% injury. Under stressful conditions (i.e. high summer temperatures) all POST herbicides caused more injury than under more favorable conditions for growth in Florida (i.e. winter). The present study identified pendimethalin, S-metolachlor, clopyralid and clethodim as potential herbicides for weed control in carinata, and flumioxazin, acifluorfen, bentazon, and carfentrazone as herbicides that can be used to control volunteer carinata plants in rotational crops.

Glyphosate-resistant (GR) common waterhemp is the fifth GR weed species confirmed in Canada, and the fourth in Ontario. As of 2017, GR common waterhemp has been confirmed in Lambton, Essex, and Chatham-Kent counties in Ontario. Greenhouse and field dose-response experiments revealed that GR common waterhemp in Ontario had a resistance level of 4.5 and 28, respectively, when compared with known glyphosate-susceptible populations. At 12 wk after application, pyroxasulfone/flumioxazin (240 g ai ha-1), pyroxasulfone/sulfentrazone (300 g ai ha-1), and S-metolachlor/metribuzin (1,943 g ai ha-1) controlled GR common waterhemp 97%, 92%, and 87%, respectively. Pyroxasulfone/sulfentrazone or S-metolachlor/metribuzin applied PRE followed by acifluorfen (600 g ai ha-1) or fomesafen (240 g ai ha-1) applied POST controlled GR common waterhemp 98% and performed better than PRE or POST alone. This research is the first to determine the resistance factor of GR common waterhemp in Ontario and identifies control strategies in soybean to mitigate the impact of common waterhemp interference in soybean crop production.Nomenclature: Acifluorfen; flumioxazin; fomesafen; glyphosate; S-metolachlor; metribuzin; pyroxasulfone; sulfentrazone; common waterhemp, Amaranthus tuberculatus var. rudis; soybean, Glycine max (L.) Merr.

Common ragweed is an important broadleaf weed in agronomic crops in the northcentral United States. A common ragweed biotype in glyphosate-resistant (GR) soybean production field in southeast Nebraska was not controlled after sequential applications of glyphosate at the labeled rate. The objectives of this study were to confirm GR common ragweed in Nebraska by quantifying the level of resistance in greenhouse and field whole-plant dose-response studies and to evaluate the response of the putative GR common ragweed to POST corn and soybean herbicides. Greenhouse whole-plant dose-response studies confirmed 7- and 19-fold resistance to glyphosate compared to the known glyphosate-susceptible (GS) biotype based on biomass reduction and control estimates, respectively. Field dose-response studies conducted in 2015 and 2016 at the putative GR common ragweed research site suggested that glyphosate doses equivalent to 15- and 40-times the labeled rate (1,260 gaeha–1) were required for 90% control and biomass reduction, respectively. Response of GR common ragweed to POST soybean herbicides in greenhouse studies indicated ≥89% control with acifluorfen, fomesafen, fomesafen plus glyphosate, glyphosate plus dicamba or 2,4-D choline, glufosinate, imazamox plus acifluorfen, and lactofen. POST corn herbicides, including 2,4-D, bromoxynil, diflufenzopyr plus dicamba, glufosinate, halosulfuron-methyl plus dicamba, mesotrione plus atrazine, and tembotrione provided ≥87% control, indicating that POST herbicides with distinct modes of action are available in corn and soybean for effective control of GR common ragweed. Results also suggested a reduced efficacy of the acetolactate synthase (ALS)-inhibiting herbicides tested in this study for control of GR and GS biotypes, indicating further research is needed to determine whether this biotype has evolved multiple herbicide resistance.