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Keywords = synthetic auxin herbicides

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15 pages, 2299 KiB  
Article
The Effects of Picloram and Clopyralid on Ocimum Basilicum (Basil)—A Study of the Uptake, Distribution and Translocation of Synthetic Auxins from Soil to Plant
by Roxana Elena Scutariu, Valentina Andreea Petre, Alina Tatarus, Diana Maria Puiu and Florentina Laura Chiriac
Environments 2025, 12(5), 144; https://doi.org/10.3390/environments12050144 - 29 Apr 2025
Viewed by 907
Abstract
The current study monitored the degree of uptake, distribution, bioaccumulation, and translocation of synthetic auxins (Picloram and Clopyralid) in medicinal plants (Basil). The study’s main objectives were the development and optimization of an analytical method for the identification and quantification of auxins, an [...] Read more.
The current study monitored the degree of uptake, distribution, bioaccumulation, and translocation of synthetic auxins (Picloram and Clopyralid) in medicinal plants (Basil). The study’s main objectives were the development and optimization of an analytical method for the identification and quantification of auxins, an optimized method of auxins extraction from soil and plant samples, and, based on the analytical results obtained, the evaluation of bioaccumulation and translocation capacity. To evaluate the effects produced by synthetic auxins on the Basil plant, three experiments were carried out in parallel (Basil-Clopyralid, Basil-Picloram, and Basil-Clopyralid-Picloram) for 15 days, where the plant was permanently exposed to a constant concentration of auxins. The study results showed that in the individual tests and the test carried out in the mixture, the highest concentration was recorded for Clopyralid in the Basil leaves, 16 µg/kg d.w., respectively, 22 µg/kg d.w. The antagonist, Picloram, was primarily detected in the plant’s roots, up to 7.2 µg/kg d.w. Therefore, Picloram favors the accumulation of Clopyralid in high percentages in all plant organs. The bioconcentration factors (BCF) and translocation factors (TF) calculation showed values lower than 1, indicating that Basil is an excluder and has no potential for phytoremediation. Full article
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19 pages, 2085 KiB  
Article
Study on Design, Synthesis and Herbicidal Activity of Novel 4-Amino-6-(5-Aryl-Substituted-1-Pyrazolyl)-3-Chloro-5-Fluoro-2-Picolinic Acids
by Huiting Li, Wei Wei, Rongchuan Shi, Yunhan Gou, Xiaofei Li, Chengyang Li, Yiqun Li, Yiming Cao and Shangzhong Liu
Molecules 2025, 30(5), 1022; https://doi.org/10.3390/molecules30051022 - 23 Feb 2025
Viewed by 1299
Abstract
6-Aryl-2-picolinic acid herbicides are an important subclass of auxin herbicides, characterized by their good absorption and conductivity, broad weed control spectrum, and excellent herbicidal activity against some resistant weeds. Based on previous studies from our group and the distinct characteristics of physico-chemical properties [...] Read more.
6-Aryl-2-picolinic acid herbicides are an important subclass of auxin herbicides, characterized by their good absorption and conductivity, broad weed control spectrum, and excellent herbicidal activity against some resistant weeds. Based on previous studies from our group and the distinct characteristics of physico-chemical properties and biological activities of active skeleton structure containing fluorine atoms, this paper introduces the design and synthesis of 41 novel 4-amino-6-(5-aryl-substituted-1-pyrazolyl)-3-chloro-5-fluoro-2-picolinic acid compounds. The test of inhibiting A. thaliana roots growth showed that most of the S-series compounds exhibited superior inhibitory effects compared to picloram, with six compounds demonstrated even better inhibitory capability than the new herbicidal molecule florpyrauxifen. For example, compound S202, at a concentration of 0.5 µmol/L, exhibited a 78.4% inhibition of A. thaliana root growth, whereas florpyrauxifen showed only a 33.8% inhibition. Root growth inhibition tests on weeds showed that 28 compounds, at a concentration of 250 µM, demonstrated a greater than 80% inhibition of Brassica napus (BN) root growth. Post-emergence herbicidal activity tests showed that most compounds exhibited good inhibitory effects on broadleaf weeds, with 10 compounds achieving a 100% inhibition of the growth of Amaranthus retroflexus L (AL). These results demonstrate that some of the 4-amino-6-(5-aryl-substituted-1-pyrazolyl)-3-chloro-5-fluoro-2-picolinic acid compounds could be used as potential lead structures in the discovery of novel synthetic auxin herbicides. Full article
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12 pages, 2218 KiB  
Article
Effects of a Novel Tripyrasulfone Herbicide on Key Soil Enzyme Activities in Paddy Rice Soil
by Penglei Sun, He Sun, Shuo Yu, Lei Lian, Tao Jin, Xuegang Peng, Xiangju Li, Weitang Liu and Hengzhi Wang
Plants 2024, 13(22), 3138; https://doi.org/10.3390/plants13223138 - 7 Nov 2024
Viewed by 1284
Abstract
Weeds significantly impact paddy yields, and herbicides offer a cost-effective, rapid, and efficient solution compared to manual weeding, ensuring agricultural productivity. Tripyrasulfone, a novel 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor developed by Qingdao Kingagroot Chemicals Co., Ltd., has demonstrated high efficacy when applied post-emergence, causing [...] Read more.
Weeds significantly impact paddy yields, and herbicides offer a cost-effective, rapid, and efficient solution compared to manual weeding, ensuring agricultural productivity. Tripyrasulfone, a novel 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor developed by Qingdao Kingagroot Chemicals Co., Ltd., has demonstrated high efficacy when applied post-emergence, causing characteristic foliar bleaching in susceptible weed species, distinct from conventional acetolactate synthase, acetyl-CoA carboxylase, and synthetic auxin herbicides. This study investigates the impact of tripyrasulfone on the activity of key soil enzymes (urease (UE), acid phosphatase (ACP), sucrase (SC), catalase (CAT), and dehydrogenase (DHA)) in paddy soils from Jilin Province and Shandong Province. Different doses of tripyrasulfone (0.1, 1.0, and 2.5 mg kg−1) were applied, and the enzymatic activities were measured. Results indicated that tripyrasulfone initially inhibited UE and ACP activities before activating them. On the 20th day after treatment, UE activity had returned to control levels, whereas ACP activity remained significantly higher, showing long-lasting activation. SC and CAT activities were inhibited but gradually recovered to control levels. Furthermore, DHA activity was activated with a sustained effect, remaining significantly higher than the control group even 20 days after treatment. Overall, the impact of tripyrasulfone on soil enzyme activities diminished over time, suggesting that tripyrasulfone posed minimal long-term ecological risk to soil health. Full article
(This article belongs to the Section Plant Protection and Biotic Interactions)
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16 pages, 4271 KiB  
Article
Dicamba: Dynamics in Straw (Maize) and Weed Control Effectiveness
by Tamara Thais Mundt, Giovanna Larissa Gimenes Cotrick Gomes, Gilmar José Picoli Junior, Ramiro Fernando Lopez Ovejero, Edivaldo Domingues Velini and Caio Antonio Carbonari
Agronomy 2024, 14(10), 2294; https://doi.org/10.3390/agronomy14102294 - 6 Oct 2024
Cited by 2 | Viewed by 1142
Abstract
Dicamba is a post-herbicide, showing some activity in soil, and its dynamics can be influenced by several factors, including the presence of straw. Brazil has more than 50% of its production area in a no-till system; thus, a good amount of the herbicide [...] Read more.
Dicamba is a post-herbicide, showing some activity in soil, and its dynamics can be influenced by several factors, including the presence of straw. Brazil has more than 50% of its production area in a no-till system; thus, a good amount of the herbicide is intercepted by the straw. This study aimed to evaluate dicamba dynamics in straw and weed control efficacy when sprayed as a PRE herbicide. For this, five different studies were conducted: we utilized different straw amounts (1) and different drought periods (2) for straw sprayed with dicamba and dicamba + glyphosate to evaluate its release from straw, different straw amounts (3), different drought periods (4), and wet and dry straw (5) to evaluate pre-emergence weed control (Bidens pilosa and Ipomoea grandifolia) and dicamba availability in medium-texture soil. Around 80% of dicamba was released from the straw after 100 mm of rainfall. One day after dicamba application, 65–70% of dicamba was released from the straw with 20 mm of rainfall, while for 7 and 14 DAA, 60% was released. Dicamba was efficient in controlling the pre-emergence of both species studied, and the amount of straw did not interfere in weed control; however, dicamba was less available in the soil after rainfall when sprayed in the straw than when sprayed directly in the soil. Up to 80% of dicamba can be released from the straw after 100 mm of rainfall and weed control was efficient for the species studied; however, the carryover effect in sensitive crops might become an issue. Full article
(This article belongs to the Section Weed Science and Weed Management)
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16 pages, 2454 KiB  
Article
Occurrence and Mechanisms Conferring Multiple Resistance to ALS-Inhibiting and Auxins Mimics Herbicides in Papaver rhoeas from Tunisia
by Myriem Chtourou, Maria Dolores Osuna, Germán Mora Marín, Zeineb Hada, Joel Torra and Thouraya Souissi
Agronomy 2024, 14(6), 1249; https://doi.org/10.3390/agronomy14061249 - 10 Jun 2024
Cited by 5 | Viewed by 1620
Abstract
Herbicide-resistant corn poppy (Papaver rhoeas L.) is one of the most important broadleaved weeds and the number of resistant cases is still growing. The aims of this study were to confirm the resistance of P. rhoeas from Tunisia to ALS inhibitors and [...] Read more.
Herbicide-resistant corn poppy (Papaver rhoeas L.) is one of the most important broadleaved weeds and the number of resistant cases is still growing. The aims of this study were to confirm the resistance of P. rhoeas from Tunisia to ALS inhibitors and auxin mimics and investigate the mechanisms of Target-Site Resistance (TSR) and Non-Target Site Resistance (NTSR) involved. Dose–response trials to determine cross-resistance patterns for ALS inhibitors and auxin mimics were conducted in a greenhouse. In this study, multiple resistance to tribenuron-methyl and dicamba but not to 2,4-D was found in P. rhoeas populations. Cross-resistance to imazamox was confirmed as well. Sequence analysis of the ALS gene detected target-site mutations in codon 197 of the ALS gene, namely, Pro197His, Pro197Thr, Pro197Leu, and Pro197Asn. In this study, the metabolism experiments with malathion (a cytochrome P450 inhibitor) showed that malathion reduced resistance to imazamox, indicating that P450 is involved in the resistance. TSR and NTSR mechanisms to ALS inhibitors likely coexist. The findings of this study revealed a significant synergistic interaction between malathion and dicamba in particular populations, suggesting that the resistance to auxin mimics can be conferred by enhanced metabolism. Full article
(This article belongs to the Special Issue Herbicides and Chemical Control of Weeds)
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18 pages, 3106 KiB  
Article
Comparative Gene Expression following 2,4-D Treatment in Two Red Clover (Trifolium pratense L.) Populations with Differential Tolerance to the Herbicide
by Lucas Pinheiro de Araujo, Michael Barrett and Randy D. Dinkins
Agronomy 2024, 14(6), 1198; https://doi.org/10.3390/agronomy14061198 - 1 Jun 2024
Viewed by 1077
Abstract
Incorporation of red clover (Trifolium pratense L.) into grass pastures can reduce the need for nitrogen fertilizer applications and increase the nutritional value of the forage. However, red clover cultivars available for Kentucky producers are highly susceptible to herbicides, such as 2,4-D [...] Read more.
Incorporation of red clover (Trifolium pratense L.) into grass pastures can reduce the need for nitrogen fertilizer applications and increase the nutritional value of the forage. However, red clover cultivars available for Kentucky producers are highly susceptible to herbicides, such as 2,4-D (2,4-dichlorophenoxy acetic acid), used for pasture broadleaf weed control. To overcome this problem, ‘UK2014’ red clover was selected for increased tolerance to 2,4-D. We employed a transcriptome analysis approach to compare the gene expression response following 2,4-D treatment of ‘UK2014’ to that of ‘Kenland’, a 2,4-D sensitive red clover and one of the parents of ‘UK2014’. The objectives were to first determine if the increased 2,4-D tolerance in ‘UK2014’ is reflected in a change of transcription response and/or a quicker recovery of a transcriptional response following 2,4-D treatment, and second, to identify genes, whether constitutively expressed or induced by 2,4-D, which could be the basis for the increased 2,4-D tolerance. Leaf tissue from the two red clovers grown in the field was collected at 4, 24, and 72 h after 2,4-D (1.12 kg 2,4-amine a.e. ha−1) treatment from both untreated and treated plants. Global gene expression was determined with reads from Illumina Hiseq 2500 mapped against the red clover draft genome, Tpv2.1 (GenBank Accession GCA_900079335.1). Genes that displayed differential expression (DEGs) following 2,4-D treatment were selected for further analysis. The number of DEGs was higher for ‘Kenland’ than for ‘UK2014’, suggesting that a lower transcriptional response corresponds with the higher 2,4-D tolerance in the ‘UK2014’ line. Similarly, gene ontology enrichment analysis revealed that expression of photosynthesis-related genes was less affected by 2,4-D in the ‘UK2014’ line than ‘Kenland’. Although we were not able to identify any specific genes that are the basis for the increased 2,4-D tolerance of ‘UK2014’, we concluded that the increased 2,4-D tolerance of ‘UK2014’ correlates with a decreased transcription response to 2,4-D. Additionally, expression of several cytochrome P450 genes that had different isoforms between ‘UK2014’ and ‘Kenland’ increased significantly in both following 2,4-D treatment, one or more of these P450s could be mediators of 2,4-D metabolism and tolerance in red clover. Full article
(This article belongs to the Special Issue Integrated Ways to Improve Forage Production and Nutritional Value)
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12 pages, 1427 KiB  
Article
Multifunctional Adjuvants Affect Sulfonylureas with Synthetic Auxin Mixture in Weed and Maize Grain Yield
by Robert Idziak, Hubert Waligóra, Leszek Majchrzak and Piotr Szulc
Plants 2024, 13(11), 1480; https://doi.org/10.3390/plants13111480 - 27 May 2024
Cited by 3 | Viewed by 1095
Abstract
A field study in the years 2017–2019 was carried out to evaluate the impact of novel adjuvant formulations on the efficacy of sulfonylurea and synthetic auxin herbicides. Treatments included nicosulfuron + rimsulfuron + dicamba (N+R+D) at full and reduced rates with three multicomponent [...] Read more.
A field study in the years 2017–2019 was carried out to evaluate the impact of novel adjuvant formulations on the efficacy of sulfonylurea and synthetic auxin herbicides. Treatments included nicosulfuron + rimsulfuron + dicamba (N+R+D) at full and reduced rates with three multicomponent (TEST-1, TEST-2, TEST-3) as well as standard (MSO, S) adjuvants. In this greenhouse study, Echinochloa crus-galli seeds were planted and treated with N+R+D at 2–3 leaf stages. The water with the desired pH (4, 7, and 9) for the preparation of the spray liquid was prepared by incorporating citric acid or K3PO4 to either lower or raise the pH of the water. Adjuvant TEST-1 added to the spray liquid at pH 4 increased the effectiveness to 68%, TEST-2 to 81%, and TEST-3 to 80%, compared to 73% and 66% with the MSO and S. The efficacy of N+R+D at pH 7 with TEST-1 increased to 83%, TEST-2 to 82%, and TEST-3 to 77%, but with MSO, it increased to 81%, and 71% with S. Adjuvants TEST-1, TEST-2, and TEST-3 in the liquid at pH 9 increased efficacy to 76 and 80%, compared to 79 and 63% with MSO or S adjuvants. N+R+D applied with TEST-1, TEST-2, and TEST-3 provided greater weed control than herbicides with surfactant (S) and similar or even better than with standard methylated seed oil (MSO) adjuvants. Maize grain yield after herbicide-with-tested-adjuvant application was higher than from an untreated check, and comparable to yield from herbicide-with-MSO treatment, but higher than from S treatment. Full article
(This article belongs to the Special Issue Sustainable Weed Management II)
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25 pages, 6597 KiB  
Article
To Bind or Not to Bind? A Comprehensive Characterization of TIR1 and Auxins Using Consensus In Silico Approaches
by Fernando D. Prieto-Martínez, Jennifer Mendoza-Cañas and Karina Martínez-Mayorga
Computation 2024, 12(5), 94; https://doi.org/10.3390/computation12050094 - 9 May 2024
Viewed by 1694
Abstract
Auxins are chemical compounds of wide interest, mostly due to their role in plant metabolism and development. Synthetic auxins have been used as herbicides for more than 75 years and low toxicity in humans is one of their most advantageous features. Extensive studies [...] Read more.
Auxins are chemical compounds of wide interest, mostly due to their role in plant metabolism and development. Synthetic auxins have been used as herbicides for more than 75 years and low toxicity in humans is one of their most advantageous features. Extensive studies of natural and synthetic auxins have been made in an effort to understand their role in plant growth. However, molecular details of the binding and recognition process are still an open question. Herein, we present a comprehensive in silico pipeline for the assessment of TIR1 ligands using several structure-based methods. Our results suggest that subtle dynamics within the binding pocket arise from water–ligand interactions. We also show that this trait distinguishes effective binders. Finally, we construct a database of putative ligands and decoy compounds, which can aid further studies focusing on synthetic auxin design. To the best of our knowledge, this study is the first of its kind focusing on TIR1. Full article
(This article belongs to the Special Issue 10th Anniversary of Computation—Computational Chemistry)
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10 pages, 1578 KiB  
Article
Alternative Integrated Weed Management Options for Clopyralid-Resistant Common Ragweed
by Greta Gallina, Bert Cregg, Eric Patterson, Erin Hill and Debalina Saha
Horticulturae 2023, 9(9), 985; https://doi.org/10.3390/horticulturae9090985 - 31 Aug 2023
Cited by 2 | Viewed by 1410
Abstract
Common ragweed (Ambrosia artemisiifolia L.) is an extremely competitive broadleaved summer annual weed found in Christmas tree production systems within Michigan. Common ragweed has been reported to have resistance to glyphosate, PSII inhibitors, PPO inhibitors, and ALS herbicides. There have been reports [...] Read more.
Common ragweed (Ambrosia artemisiifolia L.) is an extremely competitive broadleaved summer annual weed found in Christmas tree production systems within Michigan. Common ragweed has been reported to have resistance to glyphosate, PSII inhibitors, PPO inhibitors, and ALS herbicides. There have been reports from Michigan Christmas tree growers of common ragweed resistance to clopyralid, a synthetic auxin herbicide, in Montcalm County, Michigan. The objective of this study was to test alternative post-emergence herbicide combinations and organic mulch on clopyralid-resistant common ragweed for weed control efficacy. The following two stages of common ragweed were used: stage 1 (6–9 leaves) and stage 2 (12–14 leaves). For common ragweed in stage 1 in 2021 and 2022, as well as stage 2 in 2022, at all evaluation dates, mulch + clopyralid + oxyfluorfen provided the highest level of weed control. For stage 1 in 2022, this treatment combination provided 100% control from 2 weeks after treatment (WAT) and always showed better or equal weed control compared to all the other treatments. The combination of mulch + clopyralid + glyphosate provided 100% control by 2 WAT when plants were treated at stage 2 in 2022. For the plants treated at stage 1 in 2022, many of the treatments reached a fresh weight of 0 g, but in 2021, those same treatments resulted in a fresh weight of around 20 g. Based on fresh weight, the greatest plant growth occurred with glyphosate treatment in 2021 and clopyralid and mulch alone in 2022. This is likely due to common ragweed’s resistance to these herbicides. Full article
(This article belongs to the Section Floriculture, Nursery and Landscape, and Turf)
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11 pages, 2811 KiB  
Article
Filago pyramidata Tolerant to ALS-Inhibiting Herbicides: A New Invasive Weed in Olive Groves of Southern Spain
by Candelario Palma-Bautista, Jose G. Vázquez-García, José Alfredo Domínguez-Valenzuela, Ricardo Alcántara-de la Cruz, Rafael De Prado and João Portugal
Agronomy 2023, 13(5), 1273; https://doi.org/10.3390/agronomy13051273 - 28 Apr 2023
Viewed by 1936
Abstract
Weeds that usually grow in non-agricultural areas have become increasingly common invading perennial crops. Species of the genus Filago, in addition to invading Spanish olive groves, have developed certain levels of natural tolerance to the acetolactate synthase (ALS) inhibiting herbicide flazasulfuron. The [...] Read more.
Weeds that usually grow in non-agricultural areas have become increasingly common invading perennial crops. Species of the genus Filago, in addition to invading Spanish olive groves, have developed certain levels of natural tolerance to the acetolactate synthase (ALS) inhibiting herbicide flazasulfuron. The objective of this study was to determine the level and the mechanism involved in the tolerance to flazasulfuron in Filago pyramidata L., which occurs in olive groves of southern Spain, as well as to identify possible cross- or multiple-tolerances by evaluating alternative herbicides for its control. A population resistant (R) to flazasulfuron and a susceptible (S) one of Conyza canadensis were used as references. The accessions of F. pyramidata presented LD50 values (from 72 to 81 g active ingredient (ai) ha−1) higher than the field dose of flazasulfuron (50 g ai ha−1), being 11–12.5 times more tolerant than the S population of C. canadensis, but less than half the R population (170 g ai ha−1). Enzymatically, F. pyramidata was as sensitive to flazasulfuron (I50 = 17.3 μM) as the S population of C. canadensis. Filago pyramidata plants treated with flazasulfuron, combined with 4-chloro-7-nitro-2,1,3-benzoxadiazole, had a growth reduction of up to 85%, revealing the participation of glutathione-S-transferases in herbicide metabolism. Filago pyramidata presented cross-tolerance to the different chemical groups of ALS inhibitors, except triazolinones (florasulam). Synthetic auxins (2,4-D and fluroxypyr) presented good control, but some individuals survived (low multiple resistance). Cellulose synthesis, 5-enolpyruvylshikimate-3-phosphate, 4-hydroxyphenylpyruvate dioxygenase, protoporphyrinogen oxidase, photosystem I, and photosystem II inhibitor herbicides, applied in PRE or POST-emergence, presented excellent levels of control of F. pyramidata. These results confirmed the natural tolerance of F. pyramidata to flazasulfuron and cross-tolerance to most ALS-inhibiting herbicides. The mechanism involved was enhanced metabolism mediated by glutathione-S-transferases, which also conferred low multiple tolerance to synthetic auxins. Even so, herbicides with other mechanisms of action still offer excellent levels of control of F. pyramidata. Full article
(This article belongs to the Special Issue Herbicides and Chemical Control of Weeds)
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15 pages, 8948 KiB  
Article
Control of Resistant False Cleavers (Galium spurium L.) Population to ALS-Inhibiting Herbicides and Its Impact on the Growth and Yield of Durum Wheat
by Panagiotis Sparangis, Aspasia Efthimiadou, Nikolaos Katsenios and Anestis Karkanis
Agronomy 2023, 13(4), 1087; https://doi.org/10.3390/agronomy13041087 - 10 Apr 2023
Cited by 4 | Viewed by 2509
Abstract
False cleavers (Galium spurium L.) is an annual broadleaf weed, commonly found in cereal crops around the world. It reduces crop yields mainly by the competition for nutrients and plant lodging, which decreases the photosynthetic rate of cultivated plants. Two field experiments [...] Read more.
False cleavers (Galium spurium L.) is an annual broadleaf weed, commonly found in cereal crops around the world. It reduces crop yields mainly by the competition for nutrients and plant lodging, which decreases the photosynthetic rate of cultivated plants. Two field experiments were carried out in different locations to examine the efficacy of post-emergence herbicides against false cleavers in durum wheat (Triticum durum Desf.). Herbicides that belong to sulfonylureas, triazolopyrimidines, and other groups (e.g., nitriles and synthetic auxins) were applied. The results revealed that the herbicide florasulam + aminopyralid provided low efficacy (57%) against this weed species, while the most effective herbicides were bromoxynil + 2,4-D and halauxifen-methyl + florasulam. Bromoxynil + 2,4-D efficacy against false cleavers was 73% and 97% at Domokos and Velestino, respectively, while halauxifen-methyl + florasulam efficacy ranged between 89% and 97%. Moreover, the herbicides metsulfuron-methyl + bensulfuron-methyl and pyroxsulam/florasulam + 2,4-D provided low efficacy (<11%) against false cleavers, revealing resistance to ALS-inhibiting herbicides. Regarding the impact of false cleavers and other weed species on the growth of durum wheat, the results showed that the greatest dry biomass (8508.3–8922.7 kg ha−1 and 13,041.4–13,523 kg ha−1 at Domokos and Velestino, respectively) was found in the bromoxynil + 2,4-D, halauxifen-methyl + florasulam, and weed-free treatments. Similar results were also recorded for 1000-seed weights and crop yields, while there were no statistically significant differences among the treatments for spike length. Finally, our results revealed that the herbicides bromoxynil + 2,4-D and halauxifen-methyl + florasulam effectively controlled the resistant false cleavers population. However, it is important to note that halauxifen-methyl + florasulam was recently registered in Greece and other countries and, thus, should be used sensibly by farmers in a rotation with other herbicides to prevent the development of resistant populations. Full article
(This article belongs to the Section Weed Science and Weed Management)
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16 pages, 2795 KiB  
Article
Comparative Transcriptome Analysis of the Differential Effects of Florpyrauxifen-Benzyl Treatment on Phytohormone Transduction between Florpyrauxifen-Benzyl-Resistant and -Susceptible Barnyard Grasses (Echinochloa crus-galli (L.) P. Beauv)
by Wenyong Jin, Jinqiu Sun, Wei Tang, Yongjie Yang, Jianping Zhang, Yongliang Lu and Xiaoyue Yu
Agronomy 2023, 13(3), 702; https://doi.org/10.3390/agronomy13030702 - 27 Feb 2023
Cited by 9 | Viewed by 2424
Abstract
Echinochloa crus-galli (L.) P. Beauv (common name: barnyard grass) is a major weed in rice-growing areas and has evolved resistance to multiple herbicides. Florpyrauxifen-benzyl (trade name Rinskor) is a novel synthetic auxin herbicide that was approved in China in 2017 and is widely [...] Read more.
Echinochloa crus-galli (L.) P. Beauv (common name: barnyard grass) is a major weed in rice-growing areas and has evolved resistance to multiple herbicides. Florpyrauxifen-benzyl (trade name Rinskor) is a novel synthetic auxin herbicide that was approved in China in 2017 and is widely used in rice production to control resistant weeds, including barnyard grass. We identified a florpyrauxifen-benzyl-resistant E. crus-galli biotype with a resistance index (RI) of 11.89 using screen house herbicide experiments. To understand the phytotoxicity mechanisms of florpyrauxifen-benzyl, we used transcriptomics technologies to compare the gene expression profiles of florpyrauxifen-benzyl treatment on phytohormone transduction between florpyrauxifen-benzyl-resistant and -susceptible barnyard grasses (Echinochloa crus-galli (L.) P. Beauv). A total of 1810 DEGs were identified in the S comparison setting (FTS vs. UTS), and 915 DEGs were identified in the R comparison setting (FTR vs. UTR); 464 genes overlapped between the two comparison groups. Approximately sixty-nine hormone-related DEGs were detected after treatment with florpyrauxifen-benzyl in both R and S biotypes. At 24 h after florpyrauxifen-benzyl treatment, compared with the R biotype, the S biotype showed a stronger auxin response and higher expression of related genes involved in ethylene and abscisic acid biosynthesis and signal transduction. In addition, a brassinolide receptor gene was upregulated after florpyrauxifen-benzyl treatment and had higher expression in the S biotype than in the R biotype. This study is the first transcriptome analysis of the differential effects of florpyrauxifen-benzyl treatment between florpyrauxifen-benzyl-resistant and -susceptible E. crus-galli. It reflects the difference in phytohormone biosynthesis and signal transduction between R and S barnyard grasses in response to florpyrauxifen-benzyl treatment and will be helpful for understanding the phytotoxicity mechanisms of florpyrauxifen-benzyl. Full article
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20 pages, 4018 KiB  
Article
Design, Synthesis, Herbicidal Activity, and Structure–Activity Relationship Study of Novel 6-(5-Aryl-Substituted-1-Pyrazolyl)-2-Picolinic Acid as Potential Herbicides
by Tong Feng, Qing Liu, Zhi-Yuan Xu, Hui-Ting Li, Wei Wei, Rong-Chuan Shi, Li Zhang, Yi-Ming Cao and Shang-Zhong Liu
Molecules 2023, 28(3), 1431; https://doi.org/10.3390/molecules28031431 - 2 Feb 2023
Cited by 9 | Viewed by 4057
Abstract
Picolinic acid and picolinate compounds are a remarkable class of synthetic auxin herbicides. In recent years, two new picolinate compounds, halauxifen-methyl (ArylexTM active) and florpyrauxifen-benzyl (RinskorTM active), have been launched as novel herbicides. Using their structural skeleton as a template, 33 [...] Read more.
Picolinic acid and picolinate compounds are a remarkable class of synthetic auxin herbicides. In recent years, two new picolinate compounds, halauxifen-methyl (ArylexTM active) and florpyrauxifen-benzyl (RinskorTM active), have been launched as novel herbicides. Using their structural skeleton as a template, 33 4-amino-3,5-dicholor-6-(5-aryl-substituted-1-pytazolyl)-2-picolinic acid compounds were designed and synthesized for the discovery of compounds with potent herbicidal activity. The compounds were tested for inhibitory activity against the growth of Arabidopsis thaliana roots, and the results demonstrated that the IC50 value of compound V-7 was 45 times lower than that of the halauxifen-methyl commercial herbicide. Molecular docking analyses revealed that compound V-7 docked with the receptor auxin-signaling F-box protein 5 (AFB5) more intensively than picloram. An adaptive three-dimensional quantitative structure–activity relationship model was constructed from these IC50 values to guide the next step of the synthetic strategy. Herbicidal tests of the new compounds indicated that compound V-8 exhibited better post-emergence herbicidal activity than picloram at a dosage of 300 gha−1, and it was also safe for corn, wheat, and sorghum at this dosage. These results demonstrated that 6-(5-aryl-substituted-1-pyrazolyl)-2-picolinic acid compounds could be used as potential lead structures in the discovery of novel synthetic auxin herbicides. Full article
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14 pages, 1392 KiB  
Article
Impact of 40 Years Use of Different Herbicide Strategies and Crop Rotations on Weed Communities in Two Sites of the Czech Republic
by Markéta Mayerová, Jan Mikulka, Michaela Kolářová and Josef Soukup
Agriculture 2023, 13(1), 102; https://doi.org/10.3390/agriculture13010102 - 29 Dec 2022
Cited by 4 | Viewed by 2180
Abstract
Understanding the impact of farming practices on the composition of weed communities has important implications for the sustainability of weed management strategies. This study analyses data from a 40-year experiment established at two sites in the Czech Republic in 1972. The impact of [...] Read more.
Understanding the impact of farming practices on the composition of weed communities has important implications for the sustainability of weed management strategies. This study analyses data from a 40-year experiment established at two sites in the Czech Republic in 1972. The impact of herbicide strategies on the weed communities was evaluated in multi-crop rotation (MCR) with 50% cereals, and simple crop rotations (SCR) with 75% cereals. The following two herbicide strategies were compared: (1) simple treatment with synthetic auxins only in the simple crop rotation, and (2) targeted herbicide combinations with particular use of sulfonylureas, triazines, ureas and synthetic auxins. Untreated plots were included for reference purposes. Results showed that crop was the major factor determining weed community composition and explained 18% of the total variation in the case of untreated controls. However, herbicide treatment reduced the crop effect to 11%. The highest average increase of Shannon’s diversity index was by 25.4% after 44 years at the untreated plots in SCR, and it decreased by 15.1% at the treated plots in MCR. Weed species evenness € increased at all plots by an average of 23%. Simpson’s dominance index decreased at untreated plots in both crop rotations and plots treated with auxins, with the highest 44.8% decrease at the untreated plots in SCR. On the contrary, Simpson’s index increased by 33,3% on the treated plots in MCR. Herbicide selection depended on the occurrence and density of target weed species, and led to greater decrease in weed diversity and population densities in the diversified crop rotations. Full article
(This article belongs to the Special Issue Sustainable Use of Pesticides)
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12 pages, 1076 KiB  
Article
Autumn Application of Synthetic Auxin Herbicide for Weed Control in Cereals in Poland and Germany
by Łukasz Sobiech, Andrzej Joniec, Barbara Loryś, Janusz Rogulski, Monika Grzanka and Robert Idziak
Agriculture 2023, 13(1), 32; https://doi.org/10.3390/agriculture13010032 - 22 Dec 2022
Cited by 3 | Viewed by 2439
Abstract
The biological efficacy of herbicides MCPA+tribenuron-methyl (code name: MT-565 SG) and diflufenican+chlorotoluron (Legato Pro 425 SC) was estimated in eighteen field experiments on winter cereals in Poland and Germany to control broadleaf weeds. Postemergence application of tribenuron-methyl in combination with MCPA, applied at [...] Read more.
The biological efficacy of herbicides MCPA+tribenuron-methyl (code name: MT-565 SG) and diflufenican+chlorotoluron (Legato Pro 425 SC) was estimated in eighteen field experiments on winter cereals in Poland and Germany to control broadleaf weeds. Postemergence application of tribenuron-methyl in combination with MCPA, applied at the 3-leaf stage to 3 tillers detectable in autumn in winter cereals, resulted in the majority of weed species occurring in autumn being effectively eliminated with MCPA+tribenuron-methyl applied at 1.0 kg∙ha–1. It also provided an acceptable (82.4–94.1%) and comparable level of control to commonly occurring weeds Brassica napus, Capsella bursa-pastoris, Centaurea cyanus, Lamium purpureum, Tripleurospermum inodorum, Stellaria media, and Thlaspi arvense. A satisfactory level of control of 66.3 to 88.3% was confirmed for Veronica persica, Viola arvensis, and Galium aparine. According to these results, the formulation of tribenuron-methyl combined with MCPA can be recommended for application in winter cereals in the autumn as an alternative to commonly available herbicides. Full article
(This article belongs to the Special Issue Management of Weeds and Herbicide Resistance)
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