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[Objectives] The paper was to systematically study the technology of weed control in alfalfa field. [Methods] Reviving alfalfa field and newly sown alfalfa field after emergence were selected, and the effects of different herbicides on weed control and alfalfa yield were discussed. [Results] The optimal herbicides after alfalfa reviving were 5% imazethapyr and 10% imazethapyr, and the optimal dosages were 1.5 and 1.05 L/hm2, respectively. The optimal herbicides after emergence of newly born alfalfa were 5% imazethapyr and 10% imazethapyr, and the optimal dosages were 1.5 and 0.75 L/hm2, respectively. [Conclusions] This study will provide a technical support for high quality production of alfalfa. [ABSTRACT FROM AUTHOR]

Imazethapyr, a post-emergent herbicide used in worldwide soybean and corn crops, induces genetic and biochemical alterations in aquatic vertebrates. This study examined the relationship between biomarkers at different organization levels and imazethapyr real-life route exposure in Boana pulchella adults. Frogs were exposed to imazethapyr-based formulation Pivot® H (10.59%) at concentrations representing possible acute routes: field runoff (S1:10 mg.L−1), exposure after direct foliar application (S2:100 mg.L−1) and during direct foliar application (S3:1000 mg.L−1). Post-exposure, endpoints levels were evaluated: organism alterations, biochemical activities and cytogenetic assays. Forty-eight hours post-exposure, antioxidant enzymes decrease, micronuclei induction and DNA damage were observed in all scenarios, while cholinesterase activity increase and body condition reduction were observed in frog-exposed to S3. Ninety-six hours post-exposure, frogs showed glutathione-S-transferase inhibition in S1, micronuclei induction in S2 and S3, and DNA-damage increase in S3. Herbicides routes of exposures in real-life could indicate that authorized applications have a risk to amphibian populations. [ABSTRACT FROM AUTHOR]

Weed invasion causes significant yield losses in lentil. Imazethapyr (IM), a broad-spectrum herbicide inhibits the biosynthesis of branched chain amino acids necessary for plant growth. Plant growth depends upon translocation of photo-assimilates and their partitioning regulated by carbon and nitrogen metabolism. This study aimed to investigate the impact of imazethapyr spray on carbon and nitrogen metabolism in tolerant (LL1397 and LL1612) and susceptible (FLIP2004-7L and PL07) lentil genotypes during vegetative and reproductive development. Significantly higher activities of invertases and sucrose synthase (cleavage) in leaves and in podwall and seeds during early phase of development in tolerant genotypes were observed as compared to susceptible genotypes under herbicide stress that might be responsible for providing hexoses required for their growth. Activities of sucrose synthesizing enzymes, sucrose phosphate synthase and sucrose synthase (synthesis) increased significantly in podwalls and seeds of LL1397 and LL1612 genotypes during later phase of development towards maturity while the activities decreased in FLIP2004-7L and PL07 genotypes under herbicide stress. Activities of nitrate and nitrite reductase, glutamine 2-oxoglutarate aminotransferase, glutamine synthetase and glutamate dehydrogenase were increased in leaves, podwalls and seeds of LL1397 and LL1612 under herbicide stress. A proper synchronization of carbon and nitrogen metabolism in tolerant lentil genotypes during vegetative and reproductive phase might be one of the mechanisms for their recovery from herbicide stress. This first ever comprehensive information will provide a basis for future studies on the molecular mechanism of source sink relationship in lentil under herbicide stress and will be utilized in breeding programmes. • Imazethapyr (IM), a broad-spectrum herbicide controls weed invasion in lentil field. • Higher C metabolism enzymes enhanced sucrose metabolism in IM tolerant genotypes. • Higher N metabolism enzyme enhanced N assimilation in tolerant genotypes. • Coordination of C and N metabolism led to recovery in tolerant genotypes. • First report on impact of IM on source sink relationship in lentil. [ABSTRACT FROM AUTHOR]

Assessing the adaptability and stability of herbicide-tolerant lentil accessions to two broad-spectrum post-emergence herbicides in multi-environment trials has become a must in a breeding program to improve its selection. The adaptability and stability of 42 herbicide-tolerant lentil accessions were investigated using five stability parameters under eight different environments. Significant Genotype–Environment (GE) interaction was found for days to flowering (DFLR), days to maturity (DMAT), and seed yield per plant (SY). The analyzed stability parameters such as Cultivar superiority, Finlay–Wilkinson, Shukla, Static Stability, and Wricke's Ecovalence ranked the tested accessions differently, confirming the importance of using a combination of stability parameters when evaluating the performance of a group of accessions. GGE biplot of the SY trait accounted for 60.79% of sums of squares of the GE interaction and showed that cool and high rainfall environments are ideal for testing the agronomic performance of tolerant accessions. The GGE biplot of SY showed that IG4605(19), IG195(6), and IG156635(12) were specifically adapted to one mega environment, whereas IG70056(38) was identified as a superior line having a high and stable yield. These lines should be included in lentil crossing programs to develop herbicide-tolerant cultivars adapted to diverse environments. [ABSTRACT FROM AUTHOR]

Background: Generally, farmers cultivate clusterbean [Cyamopsis tetragonoloba (L.) Taub] on rainfed area but seldom adopt weed control practices in it. It becomes very difficult and uneconomical to maintain weed free environment throughout crop period in the field under rainfed conditions. Therefore, the current study was aimed to find an effective weed control practice in clusterbean under rainfed conditions. Methods: Effect of weed management practices of clusterbean with T1: Pendimethalin @ 1 litre/ha (PE), T2: Imazethapyr @ 0.1 kg/ha at 20 days (POE), T3: Stale bed technology, T4: One hand weeding at 20 DAS (days after sowing), T5: Two hand weedings at 20 and 40 DAS, T6: Imazethapyr @ 0.1 kg/ha at 20 days + hand weeding at 40 DAS, T7: Pendimethalin @ 1 litre/ha (PE) + hand weeding 35 DAS, T8: Pendimethalin @ 1 litre/ha (PE) + imazethapyr 0.1 kg/ha at 30 DAS and T9: Weedy check were investigated under rainfed conditions. Result: Weed control efficiencies of imazethapyr @ 0.1 kg/ha at 20 days + hand weeding at 40 DAS (T6), pendimethalin @ 1 litre/ha + hand weeding at 40 DAS (T7) and pendimethalin @ 1 litre/ha (PE) + imazethapyr @ 0.1 kg/ha at 20 days (PoE) (T8) were statistically similar. Imazethapyr @ 0.1 kg/ha at 20 days (PoE) + one hand weedings at 40 DAS recorded higher growth characters viz., plant height, dry matter and yield attributing characters viz., number of branches, number of pods/plant and seed index than other treatments. The highest seed yield was recorded in imazethapyr @ 0.1 kg/ha at 20 days (PoE) + one hand weedings at 40 DAS (422 kg/ha), being statistically at par with pendimethalin @ 1 litre/ha (PE) + one hand weedings at 40 DAS (390 kg/ha) and pendimethalin @ 1 litre/ha (PE) + imazethapyr @ 0.1 kg/ha at 20 days (PoE) (392 kg/ha) which was significantly higher than other treatments. Imazethapyr @ 0.1 kg/ha at 20 days (PoE) + one hand weedings at 40 DAS recorded 27.9 and 33.9 per cent higher seed yield than imazethapyr @ 0.1 kg/ha at 20 days (PoE) and one hand weedings at 40 DAS, respectively. The net returns and benefitcost ratio were maximum for imazethapyr @ 0.1 kg/ha at 20 days (PoE) + hand weeding at 40 DAS (T6). It is inferred that imazethapyr @ 0.1 kg/ha at 20 days (PoE) + one hand weedings at 40 DAS was found the most effective and economic approach for weed control in clusterbean under rainfed conditions. [ABSTRACT FROM AUTHOR]

The genetic improvement of soybean cultivars over the years has focused on increasing the yield potential and tolerance to some abiotic and biotic factors. However, during the transfer of genes of interest, some genes responsible for a lower tolerance to herbicides can be integrated into the genome of the new cultivar. Thus, the objective of this study was to evaluate the selectivity of herbicide associations applied in the postemergence period of three soybean cultivars. The experiment was conducted in a randomized completely block design, with four replications. The selected cultivars were M7110 IPRO®, Foco IPRO®, and Bônus IPRO®. The herbicides and the respective doses (g a.i. ha-1) used were glyphosate (1176), glyphosate + bentazon (1176 + 600), glyphosate + fomesafen (1176 + 175), glyphosate + lactofen (1176 + 120), glyphosate + imazethapyr (1176 + 100), glyphosate + chlorimuron (1176 + 10), glyphosate + cloransulam (1176 + 39.5), and a control without herbicide application. The visual note of intoxication was evaluated for each treatment. The components of growth and yield evaluated were height, stand, weight of one hundred grains, and yield. The application of postherbicide herbicides did not alter the plant stands of soybean cultivars. Additionally, these herbicides did not reduce the yield of the M7110 IPRO® and Foco IPRO® cultivars. Glyphosate isolated and in association with lactofen or imazethapyr reduced the grain yield of the Bônus IPRO® cultivar. [ABSTRACT FROM AUTHOR]

Western ragweed (Ambrosia psilostachya) is an invasive species in spring‐sown crops that can also cause allergic rhinitis and asthma due to its allergenic pollen. In order to evaluate the chemical and mechanical control of western ragweed, two separate experiments were conducted in 2019 and 2020. Chemical treatments included non‐treated plots, the combination of glyphosate and 2,4‐D, glyphosate + ammonium sulfate, bentazon, imazethapyr + surfactant, picloram, 2,4‐D, and mechanical treatments included: once mowing at 3–4 leaf stage, once mowing before male flowers' emergence, once mowing early female flowering stage, two mowings at 3–4 leaf stage, two mowings before male flowers' emergence. Results of these studies indicated that in both years, picloram at 0.96 kg ai ha−1 and the combination of 2,4‐D and glyphosate at 1.23 + 0.72 kg ai ha−1 provided more than 90% control of western ragweed and reduced plant height, dry weight, and density. The application of imazethapyr and bentazon, respectively, at the rates of 0.1 and 0.96 kg ai ha−1 did not cause visual damage. The mowing shortly before flowering was the most effective mechanical treatment for western ragweed control. In order to the efficient management of the western ragweed, we suggest that the mowing treatments if appropriately timed and application of glyphosate plus 2, 4‐D at 1.23 + 0.72 kg ai ha−1, and picloram at 0.96 kg ai ha−1 can prevent western ragweed from spreading by suppressing growth and reducing seed production. [ABSTRACT FROM AUTHOR]

Weeds result in a significant yield loss in mungbean (Vigna radiata [L.] R. Wilczek). However, post‐emergence (POST) herbicides are limited in mungbean for broad‐spectrum weed control. Therefore, we evaluated the efficacies of different herbicides in mungbean to find a suitable broad‐spectrum POST herbicide. Nine herbicides, weed‐free check, and unweeded control treatments were tested in a randomised block design with three replications for two consecutive years. Among the tested herbicides, clodinafop‐propargyl + sodium‐acifluorfen 122.5 g a.i. ha−1 applied at 15 days after sowing (DAS) reduced the broad‐leaved weed dry weight at 35 DAS and harvest by 55.8% and by 58.6% (p < 0.05) compared with the unweeded control respectively. Notably, it minimised the total weed dry weight by 23.1%–30.3% compared with the recommended herbicide pendimethalin 1 kg a.i. ha−1 – quizalopfop‐p‐ethyl 100 g a.i. ha−1 (p ≤ 0.05). Clodinafop‐propargyl + sodium‐acifluorfen had higher weed control index (58.2% at 35 DAS and 62.1% at harvest) over the remaining tested herbicides. Unweeded controls resulted in 51% yield loss compared with the clodinafop‐propargyl + sodium‐acifluorfen that did not differ from pendimethalin − quizalofop‐p‐ethyl for seed yield of mungbean. Decreasing order of treatment efficacy on mean grain yield across two years comprised the weed‐free check, clodinafop‐propargyl + sodium‐acifluorfen and pendimethalin − quiza‐lofop‐p‐ethyl, imazethapyr + imazamox, tembotrione, and topramezone. [Correction added on 10 November 2022, after first online publication: In the preceding sentence, changes have been made to the article content to improve clarity in this version.] Application of clodinafop‐propargyl + sodium‐acifluorfen led to the greatest increase in soil microbial biomass carbon, indicating higher levels of soil biological and rhizospheric activity. We suggest that clodinafop‐propargyl + sodium acifluorfen is a suitable broad‐spectrum option for weed management of mungbean. [ABSTRACT FROM AUTHOR]

Resistance to ALS-inhibiting herbicides has dramatically increased worldwide due to the persisting evolution of target site mutations that reduce the affinity between the herbicide and the target. We evaluated the effect of the well-known ALS Asp-376-Glu target site mutation on different imidazolinone herbicides, including imazamox and imazethapyr. Greenhouse dose response experiments indicate that the Amaranthus retroflexus biotype carrying Asp-376-Glu was fully controlled by applying the field recommended dose of imazamox, whereas it displayed high level of resistance to imazethapyr. Likewise, Sorghum halepense , carrying Asp-376-Glu showed resistance to field recommended doses of imazethapyr but not of imazamox. Biochemical inhibition and kinetic characterization of the Asp-376-Glu mutant enzyme heterologously expressed using different plant sequence backbones, indicate that the Asp-376-Glu shows high level of insensitivity to imazethapyr but not to imazamox , corroborating the greenhouse results. Docking simulations revealed that imazamox can still inhibit the Asp-376-Glu mutant enzyme through a chalcogen interaction between the oxygen of the ligand and the sulfur atom of the ALS Met200, while imazethapyr does not create such interaction. These results explain the different sensitivity of the Asp-376-Glu mutation towards imidazolinone herbicides, thus providing novel information that can be exploited for defining stewardship guidelines to manage fields infested by weeds harboring the Asp-376-Glu mutation. [Display omitted] • different imidazolinones caused similar response in ALS 376-mutants of A. retroflexus and S. halepense. • Higher resistance level to imazethapyr was observed with respect to imazamox. • In vitro ALS enzyme activity confirmed the in vivo dose-response results. • Docking and structure-activity relationships of isoforms revealed the causal features. [ABSTRACT FROM AUTHOR]

Introduction: Atwo-year researchtrialwas conductedto evaluate progressionof common bean (Phaseolus vulgaris) growth, Rhizoctonia root rot and weed development in association with productivity when treated with different cultivars, planting dates and weed controlmethods in north-western part of Iran. Methods: To determine the best descriptors, six standard curves were examined to model development of bean dry matter, Rhizoctonia root rot incidence, and weed density during two growing seasons across 256 field plots. Exponential and linear-by-linear models were fitted to bean-disease-weed progression data, and then model parameters representing over-season progress curve elements were used in multivariate regression analyses to estimate bean production. Results and discussion: Furthermore, using herbicides (Imazethapyr and Trifluralin) restricted weed density by 28% in early (mid-spring) and 42% in late (late spring to early summer) plantings. Late plantings of two bean cultivars decreased disease progress up to 36% for herbicide use, hand-weeding and control. Although bean dry matter, pod and seed production for herbicide use and hand-weeding treatments were 6-17% greater than control, late planting improved productivity in control by 10-24%. Findings suggested that late planting of bean improved efficiency of herbicides to control weeds. Late planting also restricted Rhizoctonia root rot progress and thus, improved bean yield. There were significant correlations between bean-disease-weed development descriptors. According to principal component analysis, beandisease-productivity-weed variables accounted for 80% of total data variance. Such information extends our understanding of bean-disease-weed progress in interaction with planting date to develop more effective and sustainable integrated Rhizoctonia management programs. [ABSTRACT FROM AUTHOR]

Silene conoidea L. is an annual troublesome broadleaf weed in winter wheat fields in China. In recent years, field applications of tribenuron-methyl have been ineffective in controlling S. conoidea in Hebei Province, China. The aim of this study was to determine the molecular basis of tribenuron-methyl resistance in S. conoidea. Whole-plant response assays revealed that the resistant population (R) exhibited a higher level of resistance (382.3-fold) to tribenuron-methyl. The R population also showed high cross-resistance to other acetolactate synthase (ALS) inhibitors, including imazethapyr, bispyribac-sodium and florasulam. However, the R population could be controlled by the field-recommended rates of bentazone, MCPA, fluroxypyr, carfentrazone-ethyl and bromoxynil. In vitro ALS activity assays indicated that the tribenuron-methyl I50 value for the R population was 18.5 times higher than those for the susceptible population (S). ALS gene sequencing revealed an amino acid mutation, Trp-574-Leu, in the R population. Pretreatment with the P450 inhibitor malathion indicated that the R population might have cytochrome P450-mediated metabolic resistance. These results suggest that the Trp-574-Leu mutation and P450-mediated enhanced metabolism coexist in S. conoidea to generate tribenuron-methyl resistance. This is the first time that target-site and non-target-site resistance to tribenuron-methyl has been reported in S. conoidea. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) cultivars resistant to different herbicides have generated important advances in crop management. There is a wide range of cotton resistance to herbicides, however, commercial imidazolinone (IMI)‐tolerant cultivars are not available. In this research, a new mutation that confers tolerance to IMI in cotton was isolated in the M2 generation after seed mutagenic treatments with sodium azide water solutions. The mode of inheritance of the trait was evaluated in the F2 generation by the application of imazethapyr. The inheritance corresponds to a semidominant type with a 1:2:1 distribution of tolerant/intermediate tolerance/not tolerant, in agreement with that observed in most IMI‐tolerant crops. The IMI‐tolerant line behavior was evaluated in the field nursery after the application of the herbicide in the form of foliar and pre‐emergence sprays. The tolerance level was high in pre‐emergence applications and intermediate in foliar applications compared with the nontolerant genotype, which showed a decrease in fiber yield and quality with both methods of application. After sequencing the acetohydroxyacid synthase (AHAS) gene, a point mutation corresponding to Ala205Val in the AHAS enzyme was found, which suggests it could be responsible for the increased IMI tolerance observed in cotton line SP 4172‐32. Based on results from field assays, it can be concluded that this mutant is a promising experimental line that can be used in obtaining IMI‐ tolerant commercial cotton cultivars. Core Ideas: The tolerant line presented similar performance in preplanting spraying as control without spraying.The genetic control of the IMI tolerance in the new mutant fits with a 1:2:1 ratio expected for segregation.A mutation found in the AHAS gene could be responsible for the IMI tolerance in the SP 4172‐32 mutant. [ABSTRACT FROM AUTHOR]

Context: Yield losses in lentil (Lens culinaris ssp. culinaris Medik.) caused by weeds are estimated at 20–80%. In the absence of effective broad-spectrum herbicides, the menace of weed has emerged as a serious yield constraint in lentil. Aims: Identification of tolerance to two broad-spectrum post-emergence herbicides, imazethapyr and metribuzin. Methods: 221 lentil accessions were screened at the experimental research station of the International Center for Agricultural Research in the Dry Areas, Terbol (Lebanon) over four crop seasons (2014/15–2018/19). During the 2014/15 season, a preliminary screening experiment was conducted with 221 lentil accessions in an alpha lattice design with two replications, where accessions were treated at the pre-flowering stage at 150% of the recommended dose of imazethapyr (112.5 g active ingredient/ha) or metribuzin (315 g active ingredient/ha). Based on the preliminary results, 38 accessions were selected for further evaluation. In subsequent testing, the selected accessions were screened at 100% and 150% of the recommended doses of imazethapyr or metribuzin. Key results: Herbicide treatments delayed the flowering time and maturation of tested lentil accessions. The plant height of selected tolerant accessions was reduced by 15% and 8% in the plots treated by imazethapyr and metribuzin, respectively. Reduction index (RIsy) was an effective tool to select for herbicide tolerance. Stability analysis indicated that two accessions (IG4400 and IG5722) performed under high rainfall environments while two other accessions (IG323 and IG4605) were adapted to low rainfall environments. Conclusions: Four accessions (IG323, IG5722, IG4400, IG4605) were identified as independently tolerant to metribuzin and imazethapyr. Implications: The identified herbicide-tolerant accessions can be used to develop herbicide-tolerant cultivars. The integration of herbicide-tolerant lentil in the cropping system increases its sustainability and soil fertility in West Asian and North African regions. Therefore the identified sources for herbicide tolerance combined with other traits can be used to develop new cultivars that can be adapted to modern cropping systems in the region. The cultivars can decrease the cost of the production by reducing the cost of laborious hand weeding. [ABSTRACT FROM AUTHOR]

Beckmannia syzigachne is a noxious grassy weed that infests wheat fields in China. Previously, we identified that mesosulfuron-methyl resistance in a B. syzigachne population (R, SD04) was conferred by non-target resistance, such as cytochrome P450 mixed-function oxidases (P450s)-based metabolism. RNA sequencing and real-time PCR (qRT-PCR) were used to discover potential P450s-resistant-related genes. Five cytochrome P450s (CYP704A177, CYP96B84, CYP71D7, CYP93A1, and CYP99A44) were found to be highly expressed in R plants. In this study, CYP99A44 and CYP704A177 were cloned from B. syzigachne and transferred into Arabidopsis thaliana to test the sensitivity of Arabidopsis with and without P450s genes to mesosulfuron-methyl and other acetolactate synthase (ALS)-inhibiting herbicides. Transgenic Arabidopsis overexpressing CYP99A44 became resistant to the sulfonylurea herbicide mesosulfuron-methyl, but showed no resistance to pyroxsulam, imazethapyr, flucarbazone, and bispyribac-sodium. Notably, those overexpressing CYP704A177 showed resistance to pyroxsulam and bispyribac-sodium, but not to mesosulfuron-methyl, imazethapyr, and flucarbazone. These results indicated that B. syzigachne and transgenic Arabidopsis displayed different cross-resistance patterns to ALS-inhibiting herbicides. Subcellular localization revealed that CYP99A44 and CYP704A177 protein were located in the endoplasmic reticulum. Furthermore, these results clearly indicated that CYP99A44-mediated mesosulfuron-methyl resistance in B. syzigachne and CYP704A177 may be involved in B. syzigachne cross-resistance to pyroxsulam and bispyribac-sodium. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during the rabi season of 2020-21 in Kurnool district of Andhra Pradesh in a farmers's field to access the efficacy of integrated weed management on weed dynamics in blackgram (Vigna mungo L.). Data on weed dynamics revealed that significantly lesser weed density, weed dry weight and high weed control efficiency were obtained with application of Pendimethalin 30% EC @ 1.0 kg a.i. ha-1 as PE + Imazethapyr 10% SL @ 50 g a.i. ha-1 at 25 DAS as post-emergence. The higher values of all the weed dynamics except weed control efficiency were registered with the treatment Weedy check. Growth and yield parameters of blackgram viz., plant height, number of branches plant-1, number of leaves plant-1, LAI, CGR, RGR, number of pods plant-1, length of pods, number of seeds pod-1, test weight, grain yield, stover yield and harvest index were significantly higher with the application of Pendimethalin 30% EC @ 1.0 kg a.i. ha-1 as PE + Imazethapyr 10% SL @ 50 g a.i. ha-1 at 25 DAS as post-emergence. The highest net returns and benefit-cost ratio were also recorded with the application of Pendimethalin 30% EC @ 1.0 kg a.i. ha-1 as PE + Imazethapyr 10% SL @ 50 g a.i. ha-1 at 25 DAS as postemergence. [ABSTRACT FROM AUTHOR]

Black-grass (Alopecurus myosuroides Huds.) is a common weed in Chinese wheat fields, and has become troublesome due to its evolution of herbicide resistance. One black-grass population (HN-14) collected from a wheat field where herbicides were applied was suspected to be resistant (R) to mesosulfuron-methyl. This study aims to establish a cross-resistance pattern and explore potential resistance mechanisms. The results of a whole-plant dose response assay showed that the resistant (R) population had a high of resistance to mesosulfuron-methyl (33-fold); meanwhile, no synergism of P450s activity inhibitor malathion was observed. The sequencing results revealed that ALS resistance mutation Trp-574-Leu occurred in R plants. The results of in vitro ALS enzyme activity assays also supported that the extractable ALS from R plants were 23.22-fold resistant to mesosulfuron-methyl. In the light of the "R" resistance rating system, HN-14 has evolved RRR and RR resistance to fenoxaprop-P-ethyl, clodinafop-propargyl, haloxyfop-methyl, and fluazifop-P-butyl and R? (resistance may be developing) to pinoxaden, however remains sensitive to imazethapyr, quizalofop-P-ethyl, tralkoxydim, and isoproturon. These results indicated that the mesosulfuron-methyl resistance in the black-grass population HN-14 was driven by a target-site mechanism rather than a nontarget (at least P450s-mediated) mechanism. [ABSTRACT FROM AUTHOR]

Green pigweed [Amaranthus powellii S. Wats.] is a competitive, annual, broadleaf weed that can significantly reduce soybean yield due to rapid early growth and biomass production. As a consequence of green pigweed's high competitiveness with crops, the weed species is generally managed with the use of herbicides; this may, however, lead to the selection of resistance. A green pigweed biotype with resistance to MCPA, mecoprop, dichlorprop-p, aminocyclopyrachlor (synthetic auxins), and imazethapyr (acetolactate synthase-(ALS)-inhibitor) was recently confirmed in Ontario, Canada. Research was conducted to identify alternative effective preemergence (PRE) and postemergence (POST) herbicides for the control of multiple-herbicide-resistant (MHR) green pigweed in Ontario soybean production. Four field trials, two with PRE and two with POST herbicides were conducted near Dresden, Ontario in 2019 and 2020. Visible soybean injury, green pigweed control, density, aboveground biomass, and soybean yield were evaluated following application with 19 PRE herbicide treatments and 12 POST herbicide treatments in separate studies. At 8 wk after application (WAA), pyroxasulfone/flumioxazin applied PRE controlled green pigweed 95% and was the most effective soil-applied herbicide. In the POST study, glyphosate was the most effective herbicide, controlling green pigweed 94% at 8 WAA. Imazethapyr, applied PRE or POST did not control this green pigweed biotype as it is also resistant to ALS-inhibitors. Control with other ALS-inhibiting herbicides as well as with PPO-inhibiting herbicides was variable, and further research is needed to determine the reason for variable control with these herbicides. [ABSTRACT FROM AUTHOR]

The application of flumioxazin and imazethapyr can affect the interactions between rhizobia and soybean in the rhizosphere. However, it remains unclear the effect of both herbicides, even when applied in mixture, on early nodulation and biological N fixation (BNF) in soybean, mainly related to some important biochemical traits in nodules. This study assessed the effect of flumioxazin, imazethapyr and their mixture on early nodulation and BNF in rhizosphere of soybean. The plant emergence, early nodulation, growth, and N accumulation were evaluated in soybean grown in sandy and clayey soils. The leghemoglobin content and glutamine synthetase (GS) activity were also assessed in fresh nodules. Individually, flumioxazin and imazethapyr did not affect the plant emergence, nodulation and N accumulation in soybean, while the mixture decreased significantly these parameters. Also, the values of leghemoglobin content and GS activity did not decrease with the application of the herbicides individually. The application of herbicides imazethapyr and flumioxazin separately negatively influenced the growth of soybean, while they do not influence the nodulation and N accumulation. However, the use of these herbicides in mixture can negatively influence the early nodulation and N fixation by native rhizobia. [ABSTRACT FROM AUTHOR]

To avoid yield loss in field crops associated with glyphosate‐resistant weed and changes in their population dynamics, repeated applications of glyphosate‐based herbicides (GBH) and combination with other herbicides are weed management practices (WMP) increasingly used worldwide, and particularly so in southern Quebec (Canada). These practices affect soil biological activity as well as soil functions but could also influence glyphosate and its main degradation product, the aminomethylphosphonic acid (AMPA), persistence. This study was conducted in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] field crops to evaluate the effects of single vs. repeated GBH applications, with or without the addition of other herbicides, on glyphosate and AMPA persistence in soils throughout a growing season. In corn plots, the highest glyphosate content (0.11 mg kg–1) was observed following two GBH applications combined with other herbicides (i.a. S‐metolachlor and mesotrione). In soybean plots, the highest glyphosate content (0.18 mg kg–1) was also measured following two GBH applications combined with other herbicides (i.a. imazethapyr and chlorimuron). AMPA contents in corn plots soils were similar whatever WMP employed, whereas differences were observed in soybean plots according to the WMP. Soybean plots thus seemed more responsive to variation in weed management practices than corn plots. This study highlights the persistence of glyphosate and AMPA in agricultural soils at least 8 wk after the last GBH application. Core Ideas: Both glyphosate and aminomethylphosphonic acid can persist in agricultural soils 8 wk after the last glyphosate‐based herbicides application. Glyphosate contents are higher in plots using repeated glyphosate‐based herbicide applications. Aminomethylphosphonic acid contents in soils are similar no matter the weed management practice used. Repeated glyphosate‐based herbicide applications seem to inhibit glyphosate degradation. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during summer season of 2021 with a view to find out a suitable weed management practice for sesamum by excluding commonly used herbicides and including botanical herbicides along with hand weeding. The experiment was conducted in randomized block design with 10 treatments and was replicated thrice. The treatments included one pre-emergence herbicide metribuzin at two levels, one early post-emergence herbicide imazethapyr and one post-emergence herbicide quizalofop ethyl and were applied individually and in sequence along with HW. Two plant products Ageratum conizoides and Ocimum sanctum were tried each at two levels along with HW. These treatments were compared with twice HW and unweeded control. Among the treatments, the least weed density (9.92, 9.88), weed DMP (4.96, 13.54 g/m2), highest grain yield (684 kg/ha) and stalk yield (2069 kg/ha) were recorded in pre-emergence application of metribuzin @ 100 g a.i./ha on 3 DAS+Early post-emergence application of imazethapyr @ 30 g a.i./ha on 10 DAS+HW on 20 DAS. Further, this treatment gave the highest BCR of 2.46. Treatments involving herbicides fb HW were better than plant products fb HW treatments in terms of weed density and yield. [ABSTRACT FROM AUTHOR]

Yield reduction in lentil crop due to weed infestation is a key hindrance to its growth due to poor weed-crop competition. Imazethapyr (IM), a selective herbicide, target acetolactate synthase (ALS) which catalyzes the first reaction in biosynthesis of branched chain amino acids, required for plant growth and development. The objective of the present study was to investigate the impact of IM treatment on weeds, ALS enzyme activity, antioxidant capacity, osmolyte accumulation, growth and yield related parameters in lentil genotypes. Two IM tolerant (LL1397 and LL1612) and two susceptible (FLIP2004-7L and PL07) lentil genotypes were cultivated under weed free, weedy check and IM treatments. Weed control efficiency reached its peak at 21 days after spray (DAS). Imazethapyr treatment decreased chlorophyll and carotenoid content up to 28 DAS with higher reduction in susceptible genotypes. FLIP2004-7L and PL07 had reduced plant height and lower number of pods under IM treatment which resulted in decreased seed yield. Higher ALS activity in LL1397 and LL1612 at 21 DAS, higher antioxidant capacity and glycine betaine content both at 21 and 28 DAS and lower decrease in relative leaf water content might be mediating herbicide tolerance in these genotypes that led to higher seed yield. The identified IM tolerance mechanism can be used to impart herbicide resistance in lentil. [ABSTRACT FROM AUTHOR]

A bioassay study was conducted to determine the differences in the susceptibility of selected crops to simulated imazethapyr residues based on morphological and anatomical parameters. Sugar beet, white mustard, and rapeseed oil were found to be the most sensitive based on ED50 values for the root length and the root fresh weight. Corn and sunflower were less sensitive, and wheat was the least sensitive. The measured anatomical parameters confirmed the different sensitivities of the tested plants, as evidenced by a shortening of the meristem and elongation zones, a reduction in the distance between the root tip and the absorption zone, and the distance between the root tip and the point where the primordium of the lateral root appears. An imazethapyr residue level equivalent to ED20 (for root length) did not cause serious morphological changes in the less sensitive plants, nor did it cause significant changes in the length of the root cap, the beginning of the root absorption zone (root hair region), the beginning of lateral root formation (i.e., the permanent region), and the number of root primordia per root length. Therefore, ED20 could be proposed as an acceptable residue level (ARL) or herbicide residue level at which these plants can be safely sown.

Abiotic stresses such as herbicides can affect plant growth and yield. Using herbicide-resistant plant growth-promoting bacteria is a new approach to mitigate these side effects. This study was conducted to evaluate the effect of three native plant growth-promoting bacteria isolated from the Medicago sativa rhizosphere, including Serratia rubidaea (A) and Pseudomonas putida (B), Serratia sp. (C) plus Synorhizobium meliloti (R) and their combinations (AB, AC, BC, ABC, AR, BR, CR, ABR, ACR, BCR, and ABCR) on microbial population, plant biomass, antioxidant enzymes (CAT, APX, and GPX) activities, and hydrogen peroxide and malondialdehyde contents at the presence and absence of imazethapyr herbicide. The results indicated that herbicide application decreased plant biomass but increased microbial population, antioxidant enzymes activities, and the concentrations of hydrogen peroxide and malondialdehyde of all inoculated and non-inoculated plants. Bacterial inoculation in most cases increased microbial population, plant biomass, and antioxidant activities. These increases were more evident under herbicide application. The highest increase in these attributes was achieved by AB, AR, and ABR inoculums in the presence and absence of the herbicide. The microbial population, plant biomass and antioxidant activities were decreased under BC, CR, BCR, and ABCR inoculations. It can be concluded that in addition to growth promotion, these bacteria increase resistance against herbicide stress by controlling free-radical induced oxidative stress and lipid peroxidation through antioxidant enzymes. These findings create new visions in biofertilizer preparation for reducing environmental stresses. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the efficacy of sequentially applied herbicides to control Conyza sumatrensis, one of the most widely distributed weeds worldwide, in soybean pre-sowing burndown. The study was conducted under field conditions in the state of Paraná, Brazil, at 2018-2019 growing season. The experiment consisted of a randomized block design with four replicates, with 12 treatments consisting of different herbicide mixtures applied before sowing. Control of C. sumatrensis, injury to soybean plants, and variables related to agronomic performance were evaluated. The control levels were high for all treatments, except for the one that was free of saflufenacil in either of the two applications. These results highlight the importance of saflufenacil in the control of C. sumatrensis and show promise for the use of saflufenacil/imazethapyr when considering the system and other weeds. All studied treatments were selective to soybean, which showed higher injury values in the presence of diclosulam; however, this did not compromise the agronomic performance of soybean. [ABSTRACT FROM AUTHOR]

The field experiment entitled 'Bio-efficacy of post-emergent herbicides on growth and yield of horsegram (Macrotyloma uniflorum L.)' was conducted at AICRP on Arid legumes field unit, University of Agricultural Sciences, GKVK, Bengaluru during kharif 2020. The experiment consisted of eight treatments including the application of six post emergent herbicides (Quizalofop ethyl, propaquizafop, imazethapyr, haloxyfop r-methyl, chlodinafop propargyl and fenoxafrop-p-ethyl at 15 DAS), two hand weedings (20 and 40 DAS) and weedy check were replicated thrice in RCBD. Major weeds observed were Borreria hispida, Alternanthera sessilis, Euphorbia geniculata, Acanthospermum hispidum, Parthenium hysterophorus among broad-leaved weeds, Eleusine indica, Dactyloctenium aegyptium and Cynodon dactylon among the grassy weeds and Cyperus rotundus among sedges. The results revealed that hand weedings at two intervals (20 and 40 DAS) recorded significantly higher seed yield (1155 kg ha-1) and was found on par with post emergent application of quizalofop ethyl 5 per cent EC 50 g a.i. ha-1 (1121 kg ha-1) and imazethapyr 10 per cent SL 40 g a.i. ha-1 (1082 kg ha-1) without having any phytotoxicity on horsegram. The net returns and B:C ratio was recorded higher in the treatments receiving post emergent application of quizalofop ethyl 5 per cent EC 50 g a.i. ha-1 (Rs.21,874 ha-1 and 2.1, respectively) and imazethapyr 10 per cent SL 40 g a.i. ha-1 (Rs. 20,541 ha-1 and 2.0, respectively). [ABSTRACT FROM AUTHOR]

Field experiment was conducted to study the bio-efficacy of different herbicides on growth and yield of Coriander (Coriandrum sativum L.) at Zonal Agricultural Research Station, UAS, GKVK, Bengaluru during rabi 2020-21. The experiment was laidout in RCBD design with 12 treatments replicated thrice. Major weed floras in the experimental plots were Digitaria sanguinalis L., Echinochloa colonum L., Ageratum conyzoides L. and Mollugo verticillata L. At harvest lower weed density (37.48 no. m-2), weed dry weight (12.64 g m-2) and higher weed control efficiency (81 %) were recorded from intercultivation and hand weeding at 20 DAS and 40 DAS and among herbicides pendimethalin 38.7 EC @ 1000 g a.i. ha-1 (PE)-imazethapyr 10% SL @ 25 g a.i. ha-1 (PoE) recorded significantly lower weed density (60.45 no./m²), weed dry weight (21.73 g/m²) and higher weed control efficiency (67.51 %). Intercultivation and hand weeding at 20 DAS and 40 DAS recorded significantly higher seed yield (816 kg ha-1), gross return (Rs.66027 ha-1) and net return (Rs.27527 ha-1). Among the herbicides pendimethalin 38.7 EC @ 1000 g a.i. ha-1 (PE) - imazethapyr 10% SL @ 25 g a.i. ha-1 (PoE) recorded significantly higher seed yield (676 kg ha-1), gross return (Rs.53106 ha-1) and net return (Rs.25005 ha-1), was on par with Pendimethalin 38.7 EC @ 1000 g a.i. ha-1 (PE). The cost-benefit ratio was recorded higher in pendimethalin 38.7 EC @ 1000 g a.i. ha-1 (PE) followed by pendimethalin 38.7 EC 1000 g a.i. ha-1 (PE) - imazethapyr 10% SL @ 25 g a.i. ha-1 (PoE). Weedy check recorded lower seed yield, gross return, net return and cost-benefit ratio. [ABSTRACT FROM AUTHOR]

Increased prevalence of glyphosate‐resistant (GR) weeds within agronomic cropping systems has led to the readoption of pre‐emergence (PRE) herbicides and use of multiple herbicide‐resistant soybean [Glycine max (L.) Merr.] cultivars. Herbicide programs were evaluated in the recently commercialized dicamba/glyphosate/glufosinate‐resistant (DGGR) soybean for weed control, reduction of Palmer amaranth (Amaranthus palmeri S. Watson) seed production, crop safety, and economic performance. At 35 days after pre‐emergence herbicides, acetochlor plus dicamba plus metribuzin, acetochlor/fomesafen plus dicamba, dicamba plus flumioxazin, and imazethapyr/pyroxasulfone/saflufenacil provided 80–99% control of velvetleaf (Abutilon theophrasti Medik.), Palmer amaranth, common lambsquarters (Chenopodium album L.), and Poaceae species. Evaluation at 14 days after early postemergence herbicides indicated PRE followed by (fb) POST applications of mixtures of acetochlor, dicamba, glufosinate, and glyphosate provided 80–99% weed control compared with 67–93% control in POST‐only programs. Most herbicide programs provided 83–99% control of grass and broadleaf weeds, with 85–91% weed biomass reductions at 28 days after late‐POST. The PRE fb POST programs reduced Palmer amaranth seed production by 94–99%, whereas POST‐only programs provided 75–83% reduction. In 2020, most programs provided gross profit margins ≥US$1,000 ha−1, with glufosinate fb glufosinate and imazethapyr/pyroxasulfone/saflufenacil fb acetochlor plus glufosinate providing $1,481 and $1,466 ha−1, respectively. Benefit/cost ratios ranged between 0.3 and 3.9 in 2019 due to hail but increased to 2.9–10.9 in 2020. Results of this study support use of PRE herbicides with multiple sites of action in DGGR soybean and indicate that glufosinate can provide POST control of GR Palmer amaranth. Core Ideas: Weed control was improved in most PRE fb POST herbicide programs compared with POST‐only programs.Programs that included dicamba in POST applications had reduced Palmer amaranth seed production.Glufosinate provided effective control of glyphosate‐resistant Palmer amaranth. [ABSTRACT FROM AUTHOR]