Articles de revues : « Ambrosia artemisiifolia, Amb a 1, ragweed »

1

Zhukova, N. N., M. V. Manzhos et A. V. Seleznev. « Examining sIgE-profile in patients with ambrosia allergy in Samara ». Russian Journal of Immunology 23, n^o 4 (15 octobre 2020) : 473–78. http://dx.doi.org/10.46235/1028-7221-422-esi.

Texte intégral

Résumé :

It is considered that Ambrosia trifida is not widespread in Russia, thereby avoiding its threatening effects to populational health. However, there are some areas in Russia where more than half of land area is covered by Ambrosia trifida. Many such foci are found in the Samara, Orenburg regions, Tatarstan and Bashkiria. Ambrosia trifida is distributed in Central Russia, the North Caucasus region and Siberia. The objective of the study was to examine specific IgE-profile in ragweed sensitized patients in the Samara region. A clinical and allergy examination of 969 patients with allergic rhinitis was performed. Allergic diagnostics was performed by using skin testing (prick-test) with standard set of pollen, household, and epidermal allergens. The data of skin tests in patients co-sensitized with ragweed and Artemisia allowed to analyze IgE-antibodies specific to the major Ambrosia (Amb a 1, Аmb. trifida) and Artemisia (Art v 1) allergens. Patients with negative skin test for the Amdrosia artemisiifolia and clinical manifestations of seasonal allergy were assessed for level of sIgE-antibodies nAmb a 1 and Amb trif. Skin test data demonstrated that seasonal and combined forms of allergic rhinitis dominated in patients examined. In particular, positive skin test data for pollen allergens dominated (50.6%) among all allergen groups so that more than half of them belonged to weed pollen allergens. Patients challenged with skin tests for Artemisia and ragweed allergens more likely displayed positive reaction to the Artemisia allergen (71.27%) and Ambrosia artemisiifolia (50.88%). Co-sensitization (to Artemisia and ragweed) prevailed in this geographic region featured with equal rate of simultaneously detected sIgE specific to the two types of ragweed and artemisia (nAmb a 1 + nArt v 1 + Amb trif) as well as Ambrosia trifida and Artemisia (Amb trif + nArt v 1). Almost half of the patients with negative Ambrosia art. prick-test were found to bear sIgE specific to Amb trif. Further investigation will help to better understand this phenomenon and take a fresh look at diagnostics and treatment of ragweed allergy in relevant geographic area.

Styles APA, Harvard, Vancouver, ISO, etc.

2

Singer, Ben D., Lewis H. Ziska, David A. Frenz, Dennis E. Gebhard et James G. Straka. « Research note : Increasing Amb a 1 content in common ragweed (Ambrosia artemisiifolia) pollen as a function of rising atmospheric CO2 concentration ». Functional Plant Biology 32, n^o 7 (2005) : 667. http://dx.doi.org/10.1071/fp05039.

Texte intégral

Résumé :

Although the impact of increasing atmospheric carbon dioxide concentration ([CO2]) on production of common ragweed (Ambrosia artemisiifolia L.) pollen has been examined in both indoor and outdoor experiments, the relationship between allergen expression and [CO2] is not known. An enzyme-linked immunosorbent assay (ELISA) was used to quantify Amb a 1, ragweed’s major allergen, in protein extracted from pollen of A. artemisiifolia grown at different [CO2] values in a previous experiment. The concentrations used approximated atmospheric pre-industrial conditions (i.e. at the end of the 19th century), current conditions, and the CO2 concentration projected for the middle of the 21st century (280, 370 and 600 μmol mol–1 CO2, respectively). Although total pollen protein remained unchanged, significant increases in Amb a 1 allergen were observed between pre-industrial and projected future [CO2] and between current and projected future [CO2] (1.8 and 1.6 times, respectively). These data suggest that recent and projected increases in [CO2] could directly increase the allergenicity of ragweed pollen and consequently the prevalence and / or severity of seasonal allergic disease. However, genetic and abiotic factors governing allergen expression will need to be better established to fully understand these data and their implications for public health.

Styles APA, Harvard, Vancouver, ISO, etc.

3

Traidl-Hoffmann, Claudia. « Pollenallergie gegen Ambrosia : Belastungen, Merkmale und Umgang mit einem importierten Allergieverursacher in Europa ». Kompass Pneumologie 7, n^o 2 (2019) : 86–87. http://dx.doi.org/10.1159/000497001.

Texte intégral

Résumé :

Ambrosia artemisiifolia, also known as common or short ragweed, is an invasive annual flowering herbaceous plant that has its origin in North America. Nowadays, ragweed can be found in many areas worldwide. Ragweed pollen is known for its high potential to cause type I allergic reactions in late summer and autumn and represents a major health problem in America and several countries in Europe. Climate change and urbanization, as well as long distance transport capacity, enhance the spread of ragweed pollen. Therefore ragweed is becoming domestic in non-invaded areas which in turn will increase the sensitization rate. So far 11 ragweed allergens have been described and, according to IgE reactivity, Amb a 1 and Amb a 11 seem to be major allergens. Sensitization rates of the other allergens vary between 10 and 50%. Most of the allergens have already been recombinantly produced, but most of them have not been characterized regarding their allergenic activity, therefore no conclusion on the clinical relevance of all the allergens can be made, which is important and necessary for an accurate diagnosis. Pharmacotherapy is the most common treatment for ragweed pollen allergy but fails to impact on the course of allergy. Allergen-specific immunotherapy (AIT) is the only causative and disease-modifying treatment of allergy with long-lasting effects, but currently it is based on the administration of ragweed pollen extract or Amb a 1 only. In order to improve ragweed pollen AIT, new strategies are required with higher efficacy and safety.

Styles APA, Harvard, Vancouver, ISO, etc.

4

Traidl-Hoffmann, Claudia. « Pollenallergie gegen Ambrosia : Belastungen, Merkmale und Umgang mit einem importierten Allergieverursacher in Europa ». Kompass Dermatologie 6, n^o 4 (2018) : 206–7. http://dx.doi.org/10.1159/000492639.

Texte intégral

Résumé :

Ambrosia artemisiifolia, also known as common or short ragweed, is an invasive annual flowering herbaceous plant that has its origin in North America. Nowadays, ragweed can be found in many areas worldwide. Ragweed pollen is known for its high potential to cause type I allergic reactions in late summer and autumn and represents a major health problem in America and several countries in Europe. Climate change and urbanization, as well as long distance transport capacity, enhance the spread of ragweed pollen. Therefore ragweed is becoming domestic in non-invaded areas which in turn will increase the sensitization rate. So far 11 ragweed allergens have been described and, according to IgE reactivity, Amb a 1 and Amb a 11 seem to be major allergens. Sensitization rates of the other allergens vary between 10 and 50%. Most of the allergens have already been recombinantly produced, but most of them have not been characterized regarding their allergenic activity, therefore no conclusion on the clinical relevance of all the allergens can be made, which is important and necessary for an accurate diagnosis. Pharmacotherapy is the most common treatment for ragweed pollen allergy but fails to impact on the course of allergy. Allergen-specific immunotherapy (AIT) is the only causative and disease-modifying treatment of allergy with long-lasting effects, but currently it is based on the administration of ragweed pollen extract or Amb a 1 only. In order to improve ragweed pollen AIT, new strategies are required with higher efficacy and safety.

Styles APA, Harvard, Vancouver, ISO, etc.

5

Zbîrcea, Lauriana-Eunice, Maria-Roxana Buzan, Manuela Grijincu, Elijahu Babaev, Frank Stolz, Rudolf Valenta, Virgil Păunescu, Carmen Panaitescu et Kuan-Wei Chen. « Relationship between IgE Levels Specific for Ragweed Pollen Extract, Amb a 1 and Cross-Reactive Allergen Molecules ». International Journal of Molecular Sciences 24, n^o 4 (17 février 2023) : 4040. http://dx.doi.org/10.3390/ijms24044040.

Texte intégral

Résumé :

Ragweed (Ambrosia artemisiifolia) pollen is a major endemic allergen source responsible for severe allergic manifestations in IgE-sensitized allergic patients. It contains the major allergen Amb a 1 and cross-reactive allergen molecules, such as the cytoskeletal protein profilin, Amb a 8 and calcium-binding allergens Amb a 9 and Amb a 10. To assess the importance of Amb a 1, profilin and calcium-binding allergen, the IgE reactivity profiles of clinically well-characterized 150 ragweed pollen-allergic patients were analysed regarding specific IgE levels for Amb a 1 and cross-reactive allergen molecules by quantitative ImmunoCAP measurements, IgE ELISA and by basophil activation experiments. By quantifying allergen-specific IgE levels we found that Amb a 1-specific IgE levels accounted for more than 50% of ragweed pollen-specific IgE in the majority of ragweed pollen-allergic patients. However, approximately 20% of patients were sensitized to profilin and the calcium-binding allergens, Amb a 9 and Amb a 10, respectively. As shown by IgE inhibition experiments, Amb a 8 showed extensive cross-reactivity with profilins from birch (Bet v 2), timothy grass (Phl p 12) and mugwort pollen (Art v 4) and was identified as a highly allergenic molecule by basophil activation testing. Our study indicates that molecular diagnosis performed by the quantification of specific IgE to Amb a 1, Amb a 8, Amb a 9 and Amb a 10 is useful to diagnose genuine sensitization to ragweed pollen and to identify patients who are sensitized to highly cross-reactive allergen molecules present in pollen from unrelated plants, in order to enable precision medicine-based approaches for the treatment and prevention of pollen allergy in areas with complex pollen sensitization.

Styles APA, Harvard, Vancouver, ISO, etc.

6

Rogers, B. L., J. P. Morgenstern, I. J. Griffith, X. B. Yu, C. M. Counsell, A. W. Brauer, T. P. King, R. D. Garman et M. C. Kuo. « Complete sequence of the allergen Amb alpha II. Recombinant expression and reactivity with T cells from ragweed allergic patients. » Journal of Immunology 147, n^o 8 (15 octobre 1991) : 2547–52. http://dx.doi.org/10.4049/jimmunol.147.8.2547.

Texte intégral

Résumé :

Abstract This study defines the complete primary structure of Amb alpha II, an important allergen produced by short ragweed (Ambrosia artemisiifolia). The deduced amino acid sequence derived from the cDNA indicates that Amb alpha II shares approximately 65% sequence identity with the Amb alpha I multigene family of allergens. Full-length cDNA encoding Amb alpha I.1 and Amb alpha II have been expressed in E. coli and purified. An in-frame linker encoding polyhistidine has been added to the 5' end of the cDNA to facilitate purification using Ni2+ ion affinity chromatography, yielding greater than 90% pure recombinant protein in a single step. T cells from patients allergic to ragweed proliferate in response to pollen extract as well as purified recombinant Amb alpha I.1 and Amb alpha II. T cell lines established using either Amb alpha I.1 or II as the stimulating Ag exhibit a high level of cross-reactivity to both proteins. This result is entirely consistent with the extensive primary sequence identity shared by these two proteins. These data suggest that allergic humans recognize shared T cell epitopes on these two related molecules.

Styles APA, Harvard, Vancouver, ISO, etc.

7

Bond, J. F., R. D. Garman, K. M. Keating, T. J. Briner, T. Rafnar, D. G. Klapper et B. L. Rogers. « Multiple Amb a I allergens demonstrate specific reactivity with IgE and T cells from ragweed-allergic patients. » Journal of Immunology 146, n^o 10 (15 mai 1991) : 3380–85. http://dx.doi.org/10.4049/jimmunol.146.10.3380.

Texte intégral

Résumé :

Abstract The relationship between the structure and abundance of an inhaled protein and its potential for causing an allergic response is unknown. This study analyzes Amb a I, a family of related proteins formerly known as Ag E, that comprise the major allergens of short ragweed (Ambrosia artemisiifolia). T cells isolated from ragweed allergic patients were shown to proliferate in response to purified Amb a I.1 protein from pollen in in vitro secondary cultures, demonstrating the presence of T cell stimulatory epitopes in Amb a I.1. Three recombinant forms of Amb a I (Amb a I.1, Amb a I.2, and Amb a I.3) obtained as cDNA derived from pollen mRNA were expressed in bacteria. All three recombinant forms were shown to be specifically recognized by pooled ragweed-allergic human IgE on immunoblots, confirming these gene products are important allergens. An examination of immunoblots probed with sera derived from allergic patients revealed a variation in IgE binding specificity. A minority of patients' IgE exclusively reacted with recombinant Amb a I.1, whereas most patients' IgE reacted with Amb a I.1 as well as Amb a I.2 and Amb a I.3 proteins. A detailed examination of the reactivity of T cells derived from 12 allergic patients to these recombinant Amb a I forms revealed that these allergens are all capable of stimulating T cell proliferation in in vitro assays. It is concluded that the allergic response to ragweed pollen in most allergic patients is composed of a reaction to multiple related Amb a I proteins at both the B and T cell levels.

Styles APA, Harvard, Vancouver, ISO, etc.

8

Chapoval, Svetlana P., Teresa Neeno, Christopher J. Krco, Eric V. Marietta, Jerry Harders et Chella S. David. « HLA-DQ6 and HLA-DQ8 Transgenic Mice Respond to Ragweed Allergens and Recognize a Distinct Set of Epitopes on Short and Giant Ragweed Group 5 Antigens ». Journal of Immunology 161, n^o 4 (15 août 1998) : 2032–37. http://dx.doi.org/10.4049/jimmunol.161.4.2032.

Texte intégral

Résumé :

Abstract We have investigated the genetic and molecular basis of immune responsiveness to short ragweed (SRW) (Ambrosia artemisiifolia) extract, and group 5 allergens from short and giant (Ambrosia trifida) ragweed using transgenic mice expressing DQ6 (HLA-DQA1*0103, HLA-DQB1*0601) and DQ8 (HLA-DQA1*0301, HLA-DQB1*0302) genes in class II knockout (Aβ0) mice. Panels of overlapping peptides spanning the Amb a 5 and Amb t 5 Ags were synthesized. Mice were immunized with whole SRW extract or individual peptides s.c. and lymph node cells (LNC) were challenged in vitro. Strong T cell responses to SRW extract were measured in both HLA-DQ transgenic mice, while control, HLA-DQ6−/DQ8−/H-2Aβ0, mice were unresponsive. IL-5 and IL-10 were the primary cytokines produced by in vitro challenged LNC of SRW-primed transgenic mice. HLA-DQ6-restricted T cell responses were detected to all three peptides of Amb t 5 and two determinants (residues 1–20 and 11–30) on Amb a 5. In contrast, LNC of HLA-DQ8 mice did not recognize peptide 11–30 of Amb t 5 Ag, but recognized several Amb a 5 determinants. The immune response in transgenic mice was dependent upon CD4+ T cells and was HLA-DQ restricted. Primed with purified Amb t 5, both transgenics recognized peptide 21–40, and an additional DQ6-restricted epitope was found within residue 1–20. SRW-immunized HLA-DQ6 mice respond to peptide 11–30 of Amb a 5, while HLA-DQ8 mice strongly recognize peptide 1–20. These results demonstrate the specificity of HLA class II polymorphism in allergen sensitivity and pave the way for developing antagonistic peptides for desensitization.

Styles APA, Harvard, Vancouver, ISO, etc.

9

Wang, Weiqian, Qingyue Wang, Senlin Lu, Yichun Lin, Miho Suzuki et Yuma Saito. « Behavior of Autumn Airborne Ragweed Pollen and Its Size-Segregated Allergens (Amb a 1) : A study in Urban Saitama, Japan ». Atmosphere 14, n^o 2 (26 janvier 2023) : 247. http://dx.doi.org/10.3390/atmos14020247.

Texte intégral

Résumé :

The prevalence of ragweed (Ambrosia artemisiifolia) pollinosis has been increasing worldwide. This study focused on the behavior of autumn airborne pollen and the major ragweed allergen -Amb a 1 particle in urban Saitama, Japan, in 2016. Burkard sampler results showed that the airborne ragweed pollen scattering season was from September 1st to October 9th. Over 83% of sampling events had pollen counts of over 13 grains/m3, indicating the high potential health risks of ragweed pollen in the atmosphere. The results of a surface plasmon resonance immunoassay (SPR) indicated that the average Amb a 1 count was about 16.5 pg /pollen. The airborne Amb a1 concentration was up to 4.7 ng/m3, of which about 45% was accumulated in ultrafine particles, such as particulate matter with a diameter ≤1.1 µm (PM1.1). Although ragweed pollen was hardly observed during the October 14th–17th sampling campaign, the concentration of ambient Amb a 1 particles in PM1.1 was also determined to be 4.59 ng/m3, which could be explained by the longer scattering of fine particles in the atmosphere. Pearson correlation coefficient analysis results showed that temperature (daily, r = 0.41; event, r = 0.87) could affect the behavior of the airborne pollen counts, and ambient water-soluble ions (such as Ca2+ and NO3−) could affect Amb a1 in PM1.1. Additionally, air mass trajectories and wind rose results indicated that air masses with long-range transportation could also influence the temporary behavior of Amb a1 and pollen counts via the wind. Mugwort and Humulus japonicus pollens were also observed to extend pollen scattering periods. Airborne pollen and allergenic particles could be considered air pollutants, as they pose health risks and are susceptible to environmental influences.

Styles APA, Harvard, Vancouver, ISO, etc.

10

Zhukova, N. N., M. V. Manzhos, L. R. Khabibulina et E. Yu Syrtsova. « CLINICAL AND IMMUNOLOGICAL EFFECTIVENESS OF TREATMENT OF RAGWEED POLLINOSIS IN THE SAMARA REGION ». Medical Immunology (Russia) 23, n^o 4 (19 octobre 2021) : 921–26. http://dx.doi.org/10.15789/1563-0625-cai-2210.

Texte intégral

Résumé :

Allergic rhinitis and bronchial asthma are widespread respiratory allergic diseases. In some territories of the Russian Federation, the dominant cause of pollinosis is ragweed. The aim of the study was to evaluate the clinical and immunological efficacy of ASIT with the allergen Ambrosia artemisiifolia in patients sensitized to Ambrosia trifida in the Samara region. Patients with proven sensitization to Ambrosia trifida was held immunotherapy with Ambrosia artemisiifolia allergoid preseason. After treatment, patients had a decrease in the severity of symptoms of allergic rhinitis according to VAS (p = 0.00001), a decrease in the need for medications (p = 0.0003), as well as the need for corticosteroids against the background of therapy from 34.6% to 0% (p = 0.00001). In 8% of cases, the result of treatment was good, in 69% satisfactory, in 23% unsatisfactory. In the control group, there were no changes in the severity of symptoms (p = 0.858). Also, in the control group, the need for medications remained unchanged and 14.3% of patients continued to use corticosteroids.After ASIT, there was a decrease in the level of IL-4 (p = 0.002), and a decrease in the ratio of IL-4/ IL-10 (p = 0.0063); at the same time, changes in the level of other cytokines (IL-10; IFNγ) were statistically insignificant (p > 0.05). Before treatment, the levels of IL-4/ IL-10 in both groups were comparable, and after treatment, the differences became statistically significant (p = 0.031). We did not get a statistically significant change in the level of IgG4 Amb a 1 or IgG4 Amb trifida. There was no correlation between the level of individual cytokines and the results of treatment. As a result of the conducted ASIT, positive clinical and immunological results were obtained. In most patients, the disease has acquired a controlled course. At the same time, the lack of excellent and low number of good results of ASIT is probably due to the intraspecific allergenic properties of ragweed.

Styles APA, Harvard, Vancouver, ISO, etc.

11

Ghosh, B., T. Rafnar, M. P. Perry, D. Bassolino-Klimas, W. J. Metzler, D. G. Klapper et D. G. Marsh. « Immunologic and molecular characterization of Amb p V allergens from Ambrosia psilostachya (western Ragweed) pollen. » Journal of Immunology 152, n^o 6 (15 mars 1994) : 2882–89. http://dx.doi.org/10.4049/jimmunol.152.6.2882.

Texte intégral

Résumé :

Abstract We have purified and characterized the Amb p V allergen (A1 variant) from western ragweed (Ambrosia psilostachya) pollen. This allergen was found to be highly cross-reactive with the Amb a VA1 allergen from short ragweed (A. artemisiifolia) pollen in a competitive double-Ab radioimmunoassay (DARIA) and the two allergens showed concordant allergenic potency in histamine-release experiments. We cloned and sequenced several Amb p V genes from western ragweed pollen and flowers by direct PCR of genomic DNA. The amino acid sequences deduced from the nucleotide sequences indicated the presence of multiple forms of Amb p V that could be broadly classified into two groups: Amb p VA and Amb p VB variants. The sequences of the Amb p VA variants are highly homologous to Amb a V (about 90% identity) and very similar to the protein sequence that we obtained. The Amb p VB variants share approximately 65% amino acid homology with Amb a V and have five to seven cysteine residues as compared with the eight found in Amb a V and Amb t V. Two cysteine residues that form disulfide bonds in other Amb Vs (positions 19 and 43 in Amb a V) are replaced by serine and alanine in the Amb p VB1 and Amb p VB2 variants. We have generated model structures of Amb p VA1, VA2, VA3, and VB1 variants from the nuclear magnetic resonance-derived structure of Amb a VA1 by homology modeling. Comparison of antigenic epitopes predicted for the structures of Amb p V variants and Amb a VA1 explains the observed cross-reactivity of the two ragweed proteins and suggests the epitopes likely to be involved in Ab recognition.

Styles APA, Harvard, Vancouver, ISO, etc.

12

Ghosh, B., M. P. Perry, T. Rafnar et D. G. Marsh. « Cloning and expression of immunologically active recombinant Amb a V allergen of short ragweed (Ambrosia artemisiifolia) pollen. » Journal of Immunology 150, n^o 12 (15 juin 1993) : 5391–99. http://dx.doi.org/10.4049/jimmunol.150.12.5391.

Texte intégral

Résumé :

Abstract We have cloned and sequenced Amb a V, an Ambrosia artemisiifolia (short ragweed) pollen allergen that has proved to be particularly useful in the genetic analysis of human immune responsiveness. The amino acid sequence deduced from the cloned cDNA sequence corresponds to the published sequence of the protein, except that the cDNA sequence encodes an extra 10 amino acids at the C-terminus. The expressed 55-residue protein is then presumably cleaved enzymatically at the C-terminal lysine found in the 45-residue protein isolated from the pollen. The cloning and sequencing of Amb a V genomic DNA confirmed the cDNA sequence and showed that the Amb a V gene has no introns. Recombinant Amb a V allergen, expressed in Escherichia coli, bound to IgG and IgE antibodies in all Amb a V-allergic individuals tested and inhibition studies demonstrated that the recombinant protein contains a subset of the antigenic epitopes found on native Amb a V. In addition, recombinant Amb a V released histamine efficiently from basophils from Amb a V-allergic patients. The recombinant Amb a V allergen and mutants of Amb a V should, therefore, be useful in studies of allergen epitopes in humans, as well as providing a diagnostic tool.

Styles APA, Harvard, Vancouver, ISO, etc.

13

Cao, Hui, Ling Liu, Junyi Wang, Miao Gong, Ruyi Yuan, Jiahua Lu, Xiaojun Xiao et Xiaoyu Liu. « Effects of rAmb a 1-Loaded PLGA-PEG Nanoparticles in a Murine Model of Allergic Conjunctivitis ». Molecules 27, n^o 3 (18 janvier 2022) : 598. http://dx.doi.org/10.3390/molecules27030598.

Texte intégral

Résumé :

Ambrosia artemisiifolia (Amb a) contains many allergens. Allergic conjunctivitis caused by Ambrosia artemisiifolia and its related allergen-specific immunotherapy (AIT) are seldom studied at present. poly(DL-lactide-co-glycolide)-polyethylene glycol (PLGA-PEG) is a very good nano-carrier, which has been applied in the medical field. In this context, we studied the immunotherapy effect and potential mechanism of recombinant Amb a 1 (rAmb a 1)-loaded PLGA-PEG nanoparticles. A mouse allergic conjunctivitis model was established with Ambrosia artemisiifolia crude extract, and the nanoparticles were used for AIT through direct observation of conjunctival tissue, degranulation of mast cells in conjunctival tissue, serum-specific antibodies, cytokines and other assessment models. The treatment of nanoparticles enhanced the secretion of T-helper 1 (Th1) cytokine Interferon-gama (IFN-γ) and the production of immunoglobulin G (IgG)2a (IgG2a), inhibited the secretion of T-helper 2 (Th2) cytokine Interleukin (IL)-13 and IL-4 and the level of IgE. Especially, degranulation of mast cells and expression of mast cell protease-1 (MCP-1) in conjunctival tissue was reduced significantly. In this study, we proved that the nanoparticles prepared by rAmb a 1 and PLGA-PEG have an immunotherapy effect on allergic conjunctivitis in mice.

Styles APA, Harvard, Vancouver, ISO, etc.

14

Barnes, Ethann R., Amit J. Jhala, Stevan Z. Knezevic, Peter H. Sikkema et John L. Lindquist. « Soybean and common ragweed (Ambrosia artemisiifolia) growth in monoculture and mixture ». Weed Technology 33, n^o 03 (13 mars 2019) : 481–89. http://dx.doi.org/10.1017/wet.2018.119.

Texte intégral

Résumé :

AbstractUnderstanding how plants alter their growth in response to interplant competition is an overlooked but complex problem. Previous studies have characterized the effect of light and water stress on soybean or common ragweed growth in monoculture, but no study has characterized soybean and common ragweed growth in mixture. A field study was conducted in 2015 and 2016 at the University of Nebraska-Lincoln to characterize the growth response of soybean and common ragweed with different irrigation levels and intraspecific and interspecific interference. The experiment was arranged in a split-plot design with irrigation level (0, 50%, 100% replacement of simulated evapotranspiration) as the main plot and common ragweed density (0, 2, 6, 12 plants m−1 row) as the subplot. Crop- and weed-free controls and three mixture treatments were included as subplots. Periodic destructive samples of leaf area and biomass of different organ groups were collected, and leaf area index (LAI), aboveground biomass partitioning, specific leaf area (SLA), and leaf area ratio (LAR) were calculated. Additionally, soybean and common ragweed yield were harvested, and 100-seed weight and seed production were determined. Soybean did not alter biomass partitioning, SLA, or LAR in mixture with common ragweed. Soybean LAI, biomass, and seed size were affected by increasing common ragweed density. Conversely, common ragweed partitioned less new biomass to leaves and increased SLA in response to increased interference. Common ragweed LAI, biomass, and seed number were reduced by the presence of soybean and increasing common ragweed density; however, seed weight was not affected. Results show that adjustment in biomass partitioning, SLA, and LAR is not the method that soybean uses to remain plastic under competition for light. Common ragweed demonstrated plasticity in both biomass partitioning and SLA, indicating an ability to maintain productivity under intra- and inter-specific competition for light or soil resources.

Styles APA, Harvard, Vancouver, ISO, etc.

15

Ziska, Lewis H. « Sensitivity of ragweed (Ambrosia artemisiifolia) growth to urban ozone concentrations ». Functional Plant Biology 29, n^o 11 (2002) : 1365. http://dx.doi.org/10.1071/fp02039.

Texte intégral

Résumé :

Although the sensitivity of growth and yield to ground-level ozone (O3) has been determined for a variety of agronomic crops and trees, little information is available for weedy species. Common ragweed (Ambrosia artemisiifolia L.) is recognized both as a common agricultural weed and the principle source of pollen for Fall (late August to November) allergies in North America. To quantify the extent to which ambient O3 limits growth and reproduction, ragweed was grown from germination to floral initiation at control [carbon filtered (CF), 15.8� nL� O3� L–1 air] and treatment levels (63.5 nL O3 L–1 air) of tropospheric O3. This 8-h treatment average is similar to the average 1-h O3 peak values from May through September in urban areas of Washington D.C. and Baltimore, MD. By 48 d after sowing, during floral initiation, no significant differences in total plant or floral biomass were observed as a function of O3 concentration, relative to the CF control. Analysis of leaf area ratio, relative growth rate and net assimilation rate at approximately 10-d intervals during early vegetative growth also did not demonstrate any significant effect of O3. Data from this experiment indicate that ragweed is insensitive to O3 levels up to four times that of the CF control, and suggests that O3 levels associated with urban environments may not limit the growth or reproductive development of ragweed.

Styles APA, Harvard, Vancouver, ISO, etc.

16

Zhu, X., J. L. Greenstein, B. L. Rogers et M. C. Kuo. « T cell epitope mapping of ragweed pollen allergen Ambrosia artemisiifolia (Amb a 5) and Ambrosia trifida (Amb t 5) and the role of free sulfhydryl groups in T cell recognition. » Journal of Immunology 155, n^o 10 (15 novembre 1995) : 5064–73. http://dx.doi.org/10.4049/jimmunol.155.10.5064.

Texte intégral

Résumé :

Abstract Ambrosia artemisiifolia (Amb a 5; Ra5S) and Ambrosia trifida (Amb t 5; Ra5G) are homologous allergens purified from short and giant ragweed pollen, respectively. Allergic human sera and hyperimmunized animal antisera directed against Amb a 5 or Amb t 5 show a high degree of species specificity, with little or no cross-reactivity between these two allergens, suggesting that the major Ab binding epitopes of Amb a 5 and Amb t 5 are distinct. Overlapping synthetic peptides derived from the allergen sequences were used to investigate the specificity of T cell responses in four strains of mice, BALB/c (H-2d), CBA (H-2k), C57BL/6 (H-2b), and A/J (H-2a). All four strains of mice responded to purified Amb a 5 and Amb t 5. Cross-reactivity was found at the T cell level between Amb a 5 and Amb t 5 in T cells from BALB/c, A/J, and CBA mice, but not in T cells from C57BL/6 mice. A T cell epitope from Amb a 5, residues 27-36 (PWQVVCYESS), was mapped using T cell hybridomas from BALB/c mice. A T cell epitope in Amb t 5 was mapped in the same strain to residues 24-34 (KYCVCYDSKAI). Disulfide bonds in Amb a 5 and Amb t 5 were found to be involved in T cell reactivity. Conversion of disulfide bridges into free sulfhydryl (SH) forms was required for the response of T cell hybridomas to peptide t5 (residues 27-40) from Amb t 5. Reduction of peptide a4 (residues 21-37) from Amb a 5 was essential for inducing the cross-reactivity observed with Amb t 5-specific T cell hybridomas. It is concluded that free sulfhydryl groups play a major role in the T cell recognition of cross-reactivity T cell epitopes within these related allergens.

Styles APA, Harvard, Vancouver, ISO, etc.

17

Kiprovski, Biljana, Djordje Malencic, Jadranka Lukovic et Pal Boza. « Antioxidant potential of ragweeds : Ambrosia artemisiifolia, A. trifida and Iva xanthifolia ». Zbornik Matice srpske za prirodne nauke, n^o 136 (2019) : 155–64. http://dx.doi.org/10.2298/zmspn1936155k.

Texte intégral

Résumé :

The purpose of this study was to analyze antioxidant systems among three invasive ragweed species, Ambrosia artemisiifolia L., A. trifida L. and Iva xanthifolia Nutt. Antioxidant capacity could be a possible marker of adaptation to variable environmen?tal conditions, since change in amount of antioxidants represents one of the first responses to various environmental stimuli. Among investigated ragweeds, I. xanthifolia leaves had more pronounced guaiacol peroxidase activity (87.5 and 62.5%) and reduced glutathione content (2.3 and 28.8%) than A. artemisiifolia and A. trifida, respectively. However, super?oxide dismutase activity was invariable in all investigated plants (234.1-247.5 U g-1 fresh weight). The highest content of total phenolics, tannins, flavonoids and proanthocyanidins were detected in A. trifida leaves (up to 3.7 - fold the amount of the others). According to antioxidant activity tests, investigated ragweed species could be presented in a scale: A. trifida > I. xanthifolia > A. artemisiifolia. Accumulation of non-enzymatic antioxidants and lower content of reduced glutathione point to different oxidative stress avoidance strategies of A. trifida when compared to A. artemisiifolia and I. xanthifolia within the same environ?mental conditions.

Styles APA, Harvard, Vancouver, ISO, etc.

18

Didovich, S. V., A. N. Pas', I. L. Danilova et O. P. Alekseenko. « BIORATIONAL METHOD OF AMBROSIA ARTEMISIIFOLIA L. GROWTH AND DEVELOPMENT INHIBITION ». TAURIDA HERALD OF THE AGRARIAN SCIENCES 3 (27) (2021) : 61–74. http://dx.doi.org/10.33952/2542-0720-2021-3-27-61-74.

Texte intégral

Résumé :

Currently, the search for biological agents that are alternative to chemical ones to protect agrocenoses from weeds, including quarantine objects like different types of ragweed, is relevant because they cause biological and technological damage to the environment, agriculture and have a negative impact on human health. The research was aimed at searching for biotically active elicitors of plant and microbial origin for the induction, reinforce of oxidative stress and inhibition of Ambrosia artemisiifolia L. growth. Strains were searched for and studied in 2019–2020 in laboratory experiments and greenhouse trials in the Research Institute of Agriculture of Crimea. Ragweed plants were grown in pots. Soil – chernozem southern. In the phase of 4–6 leaves, plants were treated with biorational preparative forms based on microbial and plant elicitors at a dose of 200 mkl/plant. For bioherbicidal composites, strains-inhibitors from the Research Institute of Agriculture of Crimea collection (CCM), plant extracts from the ragweed and glycerin were used. The inhibition efficiency was evaluated three weeks after treatment. The indices of height, phytomass, antioxidant status and ragweed damage degree were taken into account. We identified seven strains that inhibited plant growth by 0.13–1.08 g/plant (37–38 %) compared to the control variants: 1) water treatment, 2) bacterization with a phytopathogenic strain of Stagonosporopsis heliopsidis from the All-Russian Scientific Research Institute of Plant Protection collection. For the first time, we used ambrosia BAS to develop a birational herbicide to control the ragweed. Bacterization with biorational preparative forms based on biotically active elicitors of plant and microbial origin affected the homeostasis of ragweed, induced plant stress by blocking the enzymatic activity and the antioxidant protection systems. The activity of catalases and polyphenoloxidases decreased by 2.9–85.6 and 1.2–658.0 times, respectively, with a significant correlation between themselves (r = 0.66) and the correlation of catalase activity with plant phytomass (r = 0.72). The content of glutathione decreased by 2.5–2.7 compared to the control and had significant correlations with the activity of catalases (r = 0.63) and the phytomass of ragweed (r = 0.80) (p < 0.05) depending on the components of the biohebicidal formulations.

Styles APA, Harvard, Vancouver, ISO, etc.

19

Bohár, Gy, et L. Kiss. « First Report of Sclerotinia sclerotiorum on Common Ragweed (Ambrosia artemisiifolia) in Europe ». Plant Disease 83, n^o 3 (mars 1999) : 302. http://dx.doi.org/10.1094/pdis.1999.83.3.302c.

Texte intégral

Résumé :

Common ragweed (Ambrosia artemisiifolia L.) is reported as a host of Sclerotinia sclerotiorum (Lib.) de Bary in North America (2,4), but not in Europe. A Hungarian survey of fungal diseases of ragweed in 1994 did not find sclerotinia rot of common ragweed (A. artemisiifolia var. elatior (L.) Descourt.) (1). In autumn 1998, mature ragweed plants, 1 to 1.5 m tall, were collected from the borders of four sunflower (Helianthus annuus L.) fields in which sclerotinia rot of sunflower was frequently observed during the season, and also from six other roadside sites in Hungary. Ragweed plants exhibiting symptoms characteristic of sclerotinia rot, i.e., wilting foliage and light brown, dry lesions on the stems, were found only near two sunflower fields. Black, round to irregular or oblong sclerotia were also observed on the infected ragweed plants both externally on the stem lesions and internally, in the pith cavity. Sclerotia measured up to 5 mm in diameter and were 5 to 14 mm long. After isolation on potato dextrose agar, the pathogen produced abundant aerial mycelium and large sclerotia characteristic of S. sclerotiorum. To confirm pathogenicity, potted seedlings and mature plants of ragweed were inoculated in the greenhouse with autoclaved wheat grains colonized with mycelia of S. sclerotiorum placed 0.5 to 1 cm from the collar of the test plants. Seedlings were killed in 2 to 3 days while mature plants wilted after 5 to 6 days. In a field test, six mature plants were inoculated by attaching mycelial disks to their stems with Parafilm. These plants wilted 12 to 14 days after inoculation. The pathogen was reisolated from all diseased plants. This is the first report of S. sclerotiorum on common ragweed in Europe. Nonsclerotial mutants of the fungus (3) are being produced to be tested as potential biocontrol agents of common ragweed, which has become not only the most widespread, but also the most important allergenic plant species in Hungary since the early 1990s. References: (1) Gy. Bohár and L. Vajna. Nōvényvédelem 32:527, 1996. (2) G. J. Boland and R. Hall. Can. J. Plant Pathol. 16:93, 1994. (3) G. J. Boland and E. A. Smith. Phytopathology 81:766, 1991.(4) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

Styles APA, Harvard, Vancouver, ISO, etc.

20

DiTommaso, Antonio. « Germination behavior of common ragweed (Ambrosia artemisiifolia) populations across a range of salinities ». Weed Science 52, n^o 6 (décembre 2004) : 1002–9. http://dx.doi.org/10.1614/ws-04-030r1.

Texte intégral

Résumé :

Common ragweed is a native annual that colonizes disturbed habitats including agricultural fields and roadsides. It is especially abundant along roadways receiving regular applications of deicing salt. Anecdotal evidence has suggested that the emergence of common ragweed seedlings often occurs before the emergence of other roadside species and at salinity concentrations as high as 400 mM L−1, a level that can be found in roadside soils in early spring. However, the extent of this tolerance to salinity in common ragweed populations has not been quantified. The objective of this study was to assess the germination behavior of common ragweed seeds collected from three roadside and two agricultural populations across a salinity gradient. Seed germination of these five populations was monitored daily for 21 d across a sodium chloride gradient [0, 100, 200, 300, and 400 mM L−1] under controlled conditions. Seeds from roadside populations showed consistently greater total germination and rate of germination than seeds from agricultural populations. Germination differences were most evident at the 300 and 400 mM L−1 salinity concentrations. Average germination at the 400 mM L−1 sodium chloride concentration was 31% for two roadside populations and only 3% for two agricultural populations. Germination of seeds placed in distilled water after the 21-d salinity exposure treatments (i.e., recovery rates) was also greater for the roadside vs. agricultural populations. Findings indicate that the germination behavior of common ragweed seeds to salinity for roadside populations may be locally adaptive and allows common ragweed to emerge relatively early in spring thus providing a competitive advantage over later emerging roadside plants.

Styles APA, Harvard, Vancouver, ISO, etc.

21

Onen, Huseyin, Shahid Farooq, Hikmet Gunal, Cumali Ozaslan et Halil Erdem. « Higher Tolerance to Abiotic Stresses and Soil Types May Accelerate Common Ragweed (Ambrosia artemisiifolia) Invasion ». Weed Science 65, n^o 1 (25 octobre 2016) : 115–27. http://dx.doi.org/10.1614/ws-d-16-00011.1.

Texte intégral

Résumé :

Common ragweed is a troublesome allergenic invader and noxious weed of several crops. Despite extensive research to understand the factors affecting its invasion, the role of environmental stresses and soil types on survival and growth is poorly understood. The objective of this study was to determine the effects of drought, salinity, and soil types on survival, growth, and nutrient uptake of ragweed in greenhouse experiments to predict its invasiveness in Turkey. Three separate experiments, with five drought intensities (100, 75, 50, 25, and 12.5% of field capacity [FC]), four levels of salinity (0, 3, 6, and 12 dS m−1), and five soil types varying in sand, silt, and clay content were performed. Severe drought and salinity levels reduced seedling survival, while soil type had no effect. Increasing drought and salinity negatively affected growth and nutrient uptake; the poorest growth was observed under severe drought intensity. Ragweed exhibited intensive tolerance to drought, even severe levels, while it tolerated salinity up to 6 dS m−1 for seedling survival. Growth was negatively affected above 3 dS m−1. The highest and lowest nutrient accumulations were recorded under moderate and extreme drought intensities, respectively. Similarly, the highest Na accumulation was observed under extreme saline conditions, whereas the highest P uptake and K/Na ratio were achieved under nonsaline conditions (0 dS m−1). Variation of soil texture had no effect on growth and nutrient uptake. The highest Ca, Mg, and Na accumulations were recorded on clay soil, while higher P accrued on sandy-loam soil. Increased tolerance of ragweed to severe drought and moderate salinity and its nonselective nature for soil type indicate that semiarid and partially arid regions in Turkey have plenty of vacant niches for ragweed invasion.

Styles APA, Harvard, Vancouver, ISO, etc.

22

BOND, J., J. MORGENSTERN, A. NAULT, D. SEGAL, C. BURKE, R. CHIN et M. KUO. « 198 Distribution of the Amb a I proteins in different commercial preparations of short ragweed pollen (Ambrosia artemisiifolia) ». Journal of Allergy and Clinical Immunology 87, n^o 1 (janvier 1991) : 188. http://dx.doi.org/10.1016/0091-6749(91)91481-8.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

23

Simard, Marie-Josée, Robert E. Nurse, Eric R. Page et Gaétan Bourgeois. « Common ragweed (Ambrosia artemisiifolia) seed shattering in wheat, corn, and soybean ». Weed Science 68, n^o 5 (29 juin 2020) : 510–16. http://dx.doi.org/10.1017/wsc.2020.51.

Texte intégral

Résumé :

AbstractBefore any late-season weed control operations are planned to manage herbicide-resistant weeds, it is essential to evaluate the plants’ maturity and shattering potential. Our goal was to assess the seed-shattering phenology of common ragweed (Ambrosia artemisiifolia L.) using pollination bags as seed traps. A secondary goal was to evaluate the efficiency of these traps. Trials were conducted from 2014 to 2017 at two locations in eastern Canada (Saint-Jean-sur-Richelieu, QC, and Harrow, ON). At each location, three adjacent fields were seeded with spring wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.], or corn (Zea mays L.). Each field was divided into four replicate blocks that included two treatment plots with 5 weeds m−2 planted on the same date as the crop or when crop plants had two leaves (early or late emergence). To evaluate shattering in time, the experiment included up to 12 weekly collection dates (subplots). In each subplot, weeds were individually bagged at flowering (using mesh bags) until collection, when the number and viability of shattered and retained seeds per plant was recorded. Weather data as well as crop and weed stages were recorded. The effect of the pollen bags on seed retrieval and viability was evaluated by installing open and closed bags in corn and uncropped (bare) plots at a single location. Ambrosia artemisiifolia seed biomass was equivalent or higher in closed bags, and seed viability was equivalent or slightly reduced. No seeds were produced before harvest in spring wheat, as dispersal started in September. The percentage of seeds retained on the plant decreased linearly (1 site-year) or followed a logistic equation (4 site-years) with day of year or growing degree days. Dispersal in time was similar between early- and late-emerging weeds and similar in both corn and soybean. On average, more than 50% of A. artemisiifolia seeds were dispersed before harvest in corn and soybean.

Styles APA, Harvard, Vancouver, ISO, etc.

24

Hall, Rea Maria, Bernhard Urban, Helmut Wagentristl, Gerhard Karrer, Anna Winter, Robert Czerny et Hans-Peter Kaul. « Common Ragweed (Ambrosia artemisiifolia L.) Causes Severe Yield Losses in Soybean and Impairs Bradyrhizobium japonicum Infection ». Agronomy 11, n^o 8 (14 août 2021) : 1616. http://dx.doi.org/10.3390/agronomy11081616.

Texte intégral

Résumé :

Ambrosia artemisiifolia L. (Asteraceae), known as common ragweed, is an annual herbaceous species native to North America that has become one of the most economically important weeds in arable fields throughout Central Europe. Its large ecological amplitude enables the species to become established in several types of environments, and management options to effectively contain its spread are limited due to a lack of efficacy, high cost, or lack of awareness. In the last decade, in particular, soybean fields have been severely affected by common ragweed invasion. However, until now, information on the yield-decreasing effects of the plant has been scarce. Therefore, the aim of this study was to evaluate the competition effects of common ragweed on (1) soybean growth (aboveground/belowground), (2) the yield of two different soybean cultivars, and (3) the nodulation potential. Based on a greenhouse and biennial field trial, we found that in plots with the highest common ragweed biomass, the soybean yield loss accounted for 84% compared to the weed-free control, on average. The number of nodules, in addition to the mean nodule weight, which are tightly correlated with soybean yield, were significantly reduced by the presence of common ragweed. Just one common ragweed plant per square meter reduced the number of nodules by 56%, and consequently led to a decrease in yield of 18%. Although it has been reported that the genus Ambrosia produces and releases several types of secondary metabolites, little is known about the influence of these chemical compounds on soybean growth and nodulation. Thus, there is substantial need for research to understand the mechanisms behind the interaction between common ragweed and soybean, with a view to finding new approaches for improved common ragweed control, thereby protecting soybean and other crops against substantial yield losses.

Styles APA, Harvard, Vancouver, ISO, etc.

25

Vrbničanin, Sava. « Ambrosia trifida L. : Giant ragweed ». Acta herbologica 30, n^o 1 (2021) : 5–18. http://dx.doi.org/10.5937/actaherb2101005v.

Texte intégral

Résumé :

Ambrosia trifida L. (AMBTR, fam. Asteraceae/Compositae) is native to North America. It was introduced accidentally to Europe at the end of the 19th century, with contaminated animal feed and seeds for planting. Today A. trifida is present in ruderal and agricultural habitats of many European countries (France, Italy, Germany, Russia, Spain, Romania, Slovakia, Czech Republic, Poland, Serbia, Bulgaria, etc.). Giant ragweed was detected for the first time in 1981 in Serbia (site Čoka). Over the following period it disappeared from this site, but was recorded again in 2006 in another site (central Bačka: Despotovo, Kucura, Savino Selo, Ravno Selo, Ruski Krstur). Currently in Serbia it has the status of an alien naturalized weed species. This summer annual plant can grow up to 6 m in height and exhibits a high degree of morphological and reproductive plasticity in response to encroachment by neighboring plants. It is present in disturbed habitats, such as agriculture fields, where it plays the role of the dominant species throughout the entire growing season. In most cases, leaves are opposite and always simple and generally have 3 distinct lobes but can also have as many as 5. It is a diploid (2n = 24), meso-hygrophilic species, preferring wet habitatse and can tolerate a wide variety of soil types. Also, this is a monoecious plant, where male and female flowers are separated on the same individual. A. trifida can hybridise with A. artemisiifolia (A. x helenae Rouleau, with 2n= 27 and 2n= 33), but this hybrid has been described as sterile. Compared to other summer annual species, A. trifida is among the first to emerge in early spring, at optimal temperatures from 10-24°C. Under optimal environmental conditions, giant ragweed produces around 1,800 (max 5,100) seeds plant-1. It flowers and bears fruit from July to September (October).The pollen of this species has allergenic potential. Additionally, in the USA and Canada giant ragweed populations have developed resistance to acetolactate synthase inhibitor herbicides and glyphosate. Giant ragweed can be a problematic weed in row crops (corn, soybean, sunflower, sugerbeet) and vegetables. In A. trifida the control measures should prevent further spread, and existing populations should be controlled by integrated weed management practices. Furthermore, A. trifida has a relatively low fecundity, a transient soil seedbank and a high percentage of non-viable or low-survivorship seeds, which are features that may have constrained its establishment and spread in the current environmental conditions in Serbia.

Styles APA, Harvard, Vancouver, ISO, etc.

26

Bohár, Gy, et I. Schwarczinger. « First Report of a Septoria sp. on Common Ragweed (Ambrosia artemisiifolia) in Europe ». Plant Disease 83, n^o 7 (juillet 1999) : 696. http://dx.doi.org/10.1094/pdis.1999.83.7.696d.

Texte intégral

Résumé :

During a survey for potential biocontrol agents of common ragweed (Ambrosia artemisiifolia var. elatior (L.) Descourt) in 1997, plants exhibiting irregular, brown leaf spots were collected repeatedly from six roadside locations in Pest County, Hungary. Many pycnidia developed in the necrotic tissues on detached leaves after 2 days in moist chambers. Pycnidia were globose to slightly flattened, brown, thin walled, 58 to 100 μm in diameter, with a definite ostiole. Conidia were hyaline, filiform with 2 to 3 septa, and 22.0 to 38.0 × 0.7 to 1.3 μm in size. The fungus was isolated on potato dextrose agar and identified as a Septoria sp. To confirm pathogenicity, potted ragweed seedlings were sprayed with a suspension of 5 × 106 conidia per ml from pure cultures of the Septoria sp., placed in a dew chamber for 72 h, and then grown in a greenhouse at 16 to 24°C. After 2 weeks, inoculated plants developed small, brown lesions on leaves and leaf petioles. Three weeks after inoculation, necrotic lesions had enlarged to 1 to 3 mm in diameter with irregular, distinct margins and light brown centers. The lesions on the lower leaves were larger and more numerous than on leaves nearer the tops of the plants. Pycnidia developed on the senescent leaves after 1 month. Infected leaves became completely necrotic and occasionally entire plants died. The pathogen was reisolated from all inoculated plants, thus satisfying Koch's postulates. A voucher specimen was deposited at the Department of Botany of the Hungarian Natural History Museum in Buda-pest (No. BP 92081). Septoria ambrosiae Hemmi et Naito was described on ragweed in Japan (1), but our isolate is morphologically distinct from that species. This is the first report of a Septoria sp. on A. artemisiifolia in Europe. Reference: (1) N. Naito. Mem. Coll. Agric. Kyoto 47:41, 1940.

Styles APA, Harvard, Vancouver, ISO, etc.

27

Makra, László, István Matyasovszky, Károly Bodnár et Gábor Tusnády. « The origin and worldwide distribution of regweed ». Review on Agriculture and Rural Development 3, n^o 2 (1 janvier 2014) : 395–413. http://dx.doi.org/10.14232/rard.2014.2.395-413.

Texte intégral

Résumé :

The aim of the study is to provide a survey on the history of ragweed worldwide. Its climate dependence, impacts in agriculture, health effects and social costs are also presented. In Europe common ragweed (Ambrosia artemisiifolia) is predominant of all Ambrosia species that is supported by population genetic data. The most important habitat areas of ragweed and the highest pollen concentrations occur, in decreasing order of the pollen levels (1) in the south-western part of the European Russia, (2) in the southern and eastern parts of Ukraine, (3) in the Pannonian Plain in Central Europe, (4) in the Rhône-Alpes region in France, furthermore (5) in the Po River valley in Italy. Besides Europe, ragweed occurs in China, India, Japan and in other Asian countries, furthermore in Australia and the Unites States of America. However, beyond the USA little information is available. Warming trends due to the climate change favours the expansion of ragweed, producing higher pollen levels worldwide. In association with the warming, increasing ambient CO2 levels generate greater biomass and increased pollen production. Hence, ragweed pollen production can be expected to increase significantly under predicted future climate conditions, bringing severe impacts to areas that have yet been suffering slightly.

Styles APA, Harvard, Vancouver, ISO, etc.

28

Bohár, G., K. Varga Bohár, A. Pintye et L. Kiss. « First European Report of a Leaf Spot on Common Ragweed (Ambrosia artemisiifolia) Caused by a Phoma sp. » Plant Disease 93, n^o 7 (juillet 2009) : 763. http://dx.doi.org/10.1094/pdis-93-7-0763b.

Texte intégral

Résumé :

Common ragweed, native to North America, has recently become invasive in some parts of Europe. In Hungary, it has become the most widespread agricultural weed species and the most important producer of allergenic pollen since the 1990s. During surveys for its fungal plant pathogens to be evaluated as potential biological control agents (1), ragweed plants exhibiting necrotic spots on the leaves and stems were repeatedly found in Heves and Vas counties in Hungary in September 2004 and 2006. Numerous globose and ostiolate pycnidia, 68 to 115 μm in diameter, containing hyaline, unicellular conidia, 3 to 8 μm long, were found in necrotic tissues. On the basis of these characteristics, the fungus was identified as a Phoma sp., and 21 isolates were obtained on Czapek-Dox medium supplemented with 2% malt and 0.5% tetracycline in 2004 and 2006. Two well-sporulating isolates, designated Ph-5 and Ph-17, were selected for further studies. DNA was extracted from mycelium with a Qiagen DNeasy Plant Kit (Hilden, Germany) and the rDNA internal transcribed spacer (ITS) sequences were amplified and determined as described by Szentiványi et al. (2). The ITS sequences were identical in these two isolates and were 97 to 98% similar to those of Didymella bryoniae (anamorph Phoma cucurbitacearum), a pathogen of cucurbits, and also to those of other Phoma spp. No ITS sequences identical to those determined in Phoma isolates Ph-5 and Ph-17 were found in GenBank. Sequence data were deposited in GenBank (No. FJ794609). To test the pathogenicity of Ph-17 grown on Czapek-Dox medium with 2% malt, a 2 to 6 × 105 conidia/ml aqueous suspension was used to inoculate 2-month-old potted ragweed plants and 1-month-old cucumber cv. Rajnai fürtös, bottle gourd (Lagenaria leucantha) cv. Minibottle, and watermelon (Citrullus lanatus) cv. Sugar Baby, which were all grown from seeds in a greenhouse. Plants were kept in transparent plastic chambers for 6 weeks. Five pots with one to three plants each were used for each plant species tested and the experiment was carried out twice. Noninoculated plants, two pots with one to three individuals for each species kept in the same way, served as controls. Necrotic spots with pycnidia developed on 38 to 47% of the leaves of all inoculated ragweed plants 18 to 25 days after inoculation, whereas all the cucurbitaceous plants tested, as well as the control ragweed plants, did not develop disease symptoms. Although the Phoma isolate Ph-17 was, based on ITS sequence data, closely related to D. bryoniae, it was not pathogenic to cucurbits. The pathogen was reisolated from two diseased ragweed plants. Several Phoma spp. strains were isolated from Ambrosia artemisiifolia in the United States and Canada (3,4), but to our knowledge, none were isolated outside North America. One of the strains has already been used as a potential biological control agent of ragweed in Canada, but then lost its virulence in culture (3). The biocontrol potential of the Hungarian Phoma sp. isolate Ph-17 against A. artemisiifolia is currently being investigated. To our knowledge, this is the first report of a Phoma sp. on A. artemisiifolia in Europe. References: (1) L. Kiss. Biocontrol Sci. Technol. 17:535, 2007. (2) O. Szentiványi et al. Mycol. Res. 109:429, 2005. (3) M. P. Teshler et al. Ambrosia artemisiifolia L., Common Ragweed (Asteraceae) in: Biological Control Programmes in Canada, 1981-2000. CABI, Wallingford, UK, 2002. (4) L. Zhou et al. Mycologia 97:612, 2005.

Styles APA, Harvard, Vancouver, ISO, etc.

29

Maksimović, Tanja, Larisa Marković et Dino Hasanagić. « Influence of Ambrosia artemisiifolia extract on germination and growth of Pisum sativum L. and Phaseolus vulgaris L. seedlings ». Zemljiste i biljka 70, n^o 2 (2021) : 33–41. http://dx.doi.org/10.5937/zembilj2102033m.

Texte intégral

Résumé :

Previous research has shown that there are allelopathic interactions between plants, releasing allelochemicals for which it is still unknown whether they are randomly generated or transmitted from generation to generation. In this paper, the influence dried ragweed leaves (Ambrosia artemisiifolia L.) aqueous extract of different concentrations: concentrated extract (10%), extract diluted to 1/2 (5%); 1/4 (2.5%) and 1/8 (1.25%) on germination and growth of peas and beans was monitored. The results showed that the increased concentration of ragweed extract inhibited germination, prolonged germination time and decreased the germination index of both test plant species compared to the control. The ragweed extract (concentrated and 1/2) reduced the growth of shoots and roots compared to the control (by more than 50%), with the inhibitory effect being more visible on young pea plants compared to beans. The results of the research showed that the presence of ragweed as a weed in the field significantly reduces the germination and growth of cultivated plants, which is why care should be taken to suppress and remove it in a timely manner.

Styles APA, Harvard, Vancouver, ISO, etc.

30

Moingeon, Philippe, Julien Bouley, Maxime Le Mignon, Véronique Baron-Bodo, Véronique Bordas, Laetitia Bussières, Marie-Noëlle Couret et al. « Identification Of The Cysteine Protease Amb a x As A Novel Major Allergen From Short Ragweed Pollen (Ambrosia artemisiifolia) ». Journal of Allergy and Clinical Immunology 133, n^o 2 (février 2014) : AB101. http://dx.doi.org/10.1016/j.jaci.2013.12.377.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

31

Ganie, Zahoor A., et Amit J. Jhala. « Glyphosate-Resistant Common Ragweed (Ambrosia artemisiifolia) in Nebraska : Confirmation and Response to Postemergence Corn and Soybean Herbicides ». Weed Technology 31, n^o 2 (mars 2017) : 225–37. http://dx.doi.org/10.1017/wet.2016.26.

Texte intégral

Résumé :

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.

Styles APA, Harvard, Vancouver, ISO, etc.

32

Ganie, Zahoor A., Mithila Jugulam et Amit J. Jhala. « Temperature Influences Efficacy, Absorption, and Translocation of 2,4-D or Glyphosate in Glyphosate-Resistant and Glyphosate-Susceptible Common Ragweed (Ambrosia artemisiifolia) and Giant Ragweed (Ambrosia trifida) ». Weed Science 65, n^o 5 (9 août 2017) : 588–602. http://dx.doi.org/10.1017/wsc.2017.32.

Texte intégral

Résumé :

Glyphosate and 2,4-D have been commonly used for control of common and giant ragweed before planting of corn and soybean in the midwestern United States. Because these herbicides are primarily applied in early spring, environmental factors such as temperature may influence their efficacy. The objectives of this study were to (1) evaluate the influence of temperature on the efficacy of 2,4-D or glyphosate for common and giant ragweed control and the level of glyphosate resistance and (2) determine the underlying physiological mechanisms (absorption and translocation). Glyphosate-susceptible (GS) and glyphosate-resistant (GR) common and giant ragweed biotypes from Nebraska were used for glyphosate dose–response studies, and GR biotypes were used for 2,4-D dose–response studies conducted at two temperatures (day/night [d/n]; low temperature [LT]: 20/11 C d/n; high temperature [HT]: 29/17 C d/n). Results indicate improved efficacy of 2,4-D or glyphosate at HT compared with LT for common and giant ragweed control regardless of susceptibility or resistance to glyphosate. The level of glyphosate resistance decreased in both the species at HT compared with LT, primarily due to more translocation at HT. More translocation of 2,4-D in GR common and giant ragweed at HT compared with LT at 96 h after treatment could be the reason for improved efficacy. Similarly, higher translocation in common ragweed and increased absorption and translocation in giant ragweed resulted in greater efficacy of glyphosate at HT compared with LT. It is concluded that the efficacy of 2,4-D or glyphosate for common and giant ragweed control can be improved if applied at warm temperatures (29/17 C d/n) due to increased absorption and/or translocation compared with applications during cooler temperatures (20/11 C d/n).

Styles APA, Harvard, Vancouver, ISO, etc.

33

ZWOLLO, P., A. ANSARI et D. MARSH. « Association of class II DNA restriction fragments with responsiveness to Ambrosia artemisiifolia (short ragweed)-pollen allergen Amb a V in ragweed-allergic patients1, 2 ». Journal of Allergy and Clinical Immunology 83, n^o 1 (janvier 1989) : 45–54. http://dx.doi.org/10.1016/0091-6749(89)90476-4.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

34

Griffith, I. J., J. Pollock, D. G. Klapper, B. L. Rogers et A. K. Nault. « Sequence Polymorphism of Amb a I and Amb a II, the Major Allergens in Ambrosia artemisiifolia (Short Ragweed) ». International Archives of Allergy and Immunology 96, n^o 4 (1991) : 296–304. http://dx.doi.org/10.1159/000235512.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

35

Léonard, Renaud, Nicole Wopfner, Martin Pabst, Johannes Stadlmann, Bent O. Petersen, Jens Ø. Duus, Martin Himly et al. « A New Allergen from Ragweed (Ambrosia artemisiifolia) with Homology to Art v 1 from Mugwort ». Journal of Biological Chemistry 285, n^o 35 (24 juin 2010) : 27192–200. http://dx.doi.org/10.1074/jbc.m110.127118.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

36

Wayne, Peter, Susannah Foster, John Connolly, Fakhri Bazzaz et Paul Epstein. « Production of allergenic pollen by ragweed (Ambrosia artemisiifolia L.) is increased in CO2-enriched atmospheres ». Annals of Allergy, Asthma & ; Immunology 88, n^o 3 (mars 2002) : 279–82. http://dx.doi.org/10.1016/s1081-1206(10)62009-1.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

37

Ziska, Lewis H., et Frances A. Caulfield. « Rising CO2 and pollen production of common ragweed (Ambrosia artemisiifolia L.), a known allergy-inducing species : implications for public health. » Functional Plant Biology 27, n^o 10 (2000) : 893. http://dx.doi.org/10.1071/pp00032.

Texte intégral

Résumé :

Although environmental factors such as precipitation and temperature are recognized as influencing pollen production, the impact of rising atmospheric carbon dioxide concentration ([CO2]) on the potential growth and pollen production of hay-fever-inducing plants is unknown. Here we present measurements of growth and pollen production of common ragweed (Ambrosia artemisiifolia L.) from pre-industrial [CO2] (280 mol mol–1) to current concentrations (370 mol mol–1) to a projected 21st century concentration (600 mol mol–1). We found that exposure to current and elevated [CO2] increased ragweed pollen production by 131 and 320%, respectively, compared to plants grown at pre-industrial [CO2]. The observed stimulations of pollen production from the pre-industrial [CO2] were due to an increase in the number (at 370 mol mol–1) and number and size (at 600 mol mol–1) of floral spikes. Overall, floral weight as a percentage of total plant weight decreased (from 21% to 13%), while investment in pollen increased (from 3.6 to 6%) between 280 and 600 mol mol–1 CO2. Our results suggest that the continuing increase in atmospheric [CO2] could directly influence public health by stimulating the growth and pollen production of allergy-inducing species such as ragweed.

Styles APA, Harvard, Vancouver, ISO, etc.

38

Byker, Holly P., Annemarie C. Van Wely, Amit J. Jhala, Nader Soltani, Darren E. Robinson, Mark B. Lawton et Peter H. Sikkema. « Preplant followed by postemergence herbicide programs and biologically effective rate of metribuzin for control of glyphosate-resistant common ragweed (Ambrosia artemisiifolia) in soybean ». Canadian Journal of Plant Science 98, n^o 4 (1 août 2018) : 809–14. http://dx.doi.org/10.1139/cjps-2017-0299.

Texte intégral

Résumé :

With no new herbicides with a novel mode of action in the marketplace in corn–soybean cropping systems, control of glyphosate-resistant (GR) weeds requires the re-evaluation of existing herbicides. This necessitates a renewed focus on using herbicide tank-mixes and sequential herbicide programs while also striving to minimize the environmental impact of weed management. Preliminary research identified four preplant (PP) herbicides (2,4-D, saflufenacil/dimethenamid-P, linuron, and metribuzin) and one postemergence (POST) herbicide (fomesafen) that provided good but inconsistent control of GR common ragweed when applied alone in soybean. The objectives of this study were to determine the biologically effective rate of metribuzin and evaluate PP followed by POST herbicide programs for control of GR common ragweed in soybean. The aforementioned PP herbicides reduced GR common ragweed density and aboveground biomass by 82%–94% and 55%–89%, respectively. In contrast, a PP herbicide followed by fomesafen applied POST decreased common ragweed densities and aboveground biomass by 97%–99% and 93%–98%, respectively. Metribuzin applied at 824 and 1015 g a.i. ha−1 controlled GR common ragweed 90% at 4 and 8 wk after application, respectively. This study concludes that GR common ragweed can be controlled with a PP followed by POST herbicide program and metribuzin has potential for control of GR common ragweed in soybean.

Styles APA, Harvard, Vancouver, ISO, etc.

39

MUTCH, DALE R., TODD E. MARTIN et KEVIN R. KOSOLA. « Red Clover (Trifolium pratense) Suppression of Common Ragweed (Ambrosia artemisiifolia) in Winter Wheat (Triticum aestivum)1 ». Weed Technology 17, n^o 1 (janvier 2003) : 181–85. http://dx.doi.org/10.1614/0890-037x(2003)017[0181:rctpso]2.0.co;2.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

40

Gronwald, John W., Kathryn L. Plaisance et Bryan A. Bailey. « Effects of the fungal protein Nep1 and Pseudomonas syringae on growth of Canada thistle (Cirsium arvense), common ragweed (Ambrosia artemisiifolia), and common dandelion (Taraxacum officinale) ». Weed Science 52, n^o 1 (février 2004) : 98–104. http://dx.doi.org/10.1614/ws-03-021r.

Texte intégral

Résumé :

The effects of the fungal protein Nep1 and Pseudomonas syringae pv. tagetis (Pst) applied separately or in combination on Canada thistle, common ragweed, and common dandelion were examined in growth chamber experiments. Experiments examined five treatments: (1) untreated control, (2) Silwet L-77 (0.3%, v/v) control, (3) Nep1 (5 μg ml−1) plus Silwet L-77 (0.3%, v/v), (4) Pst (109 colony-forming units [cfu] ml−1) plus Silwet L-77 (0.3%, v/v), and (5) Pst (109 cfu ml−1) and Nep1 (5 μg ml−1) plus Silwet L-77 (0.3%, v/v). Foliar treatments were applied at 28, 26, and 21 d after planting for Canada thistle, common dandelion, and common ragweed, respectively. For all three species, foliar application of Nep1 alone or in combination with Pst caused rapid desiccation and necrosis of leaves, with the greatest effect on recent, fully expanded (RFE) leaves. Within 4 to 8 h after treatment (HAT), 60 to 80% of RFE leaves of all three species were necrotic. Measured 72 HAT, Pst populations in Canada thistle leaves treated with Nep1 plus Pst were approximately 105 cfu cm−2 compared with 107 cfu cm−2 for leaves treated with Pst alone. Measured 2 wk after treatment, foliar application of Nep1 reduced shoot dry weight of the three weeds by 30 to 41%. Treatment with Pst reduced shoot growth of common ragweed, Canada thistle, and common dandelion by 82, 31, and 41%, respectively. The large suppression of common ragweed shoot growth caused by Pst treatment was associated with a high percentage (60%) of leaf area exhibiting chlorosis. Treatment with Pst plus Nep1 did not result in significant decreases in shoot dry weight for Canada thistle and common dandelion compared with either treatment alone. For common ragweed, shoot growth reduction caused by applying Pst and Nep1 together was not greater than that caused by Pst alone.

Styles APA, Harvard, Vancouver, ISO, etc.

41

Robinson, Darren E., Kristen McNaughton et Nader Soltani. « Weed Management in Transplanted Bell Pepper (Capsicum annuum) with Pretransplant Tank Mixes of Sulfentrazone, S-metolachlor, and Dimethenamid-p ». HortScience 43, n^o 5 (août 2008) : 1492–94. http://dx.doi.org/10.21273/hortsci.43.5.1492.

Texte intégral

Résumé :

Pepper growers currently have limited access to many effective broadleaf herbicides. Field trials were conducted over a 3-year period in Ontario to study the effect of tank mixtures of sulfentrazone (100 or 200 g·ha−1 a.i.) with either s-metolachlor (1200 or 2400 g·ha−1 a.i.) or dimethenamid-p (750 or 1500 g·ha−1 a.i.) on transplanted bell pepper. Under weed-free conditions, there was no visual injury or reduction in plant height, fruit number, fruit size, or marketable yield of transplanted pepper with pretransplant applications of sulfentrazone applied in tank mixtures with s-metolachlor or dimethenamid-p. The tank mixture of sulfentrazone + s-metolachlor gave greater than 85% control of redroot pigweed (Amaranthus retroflexus) and eastern black nightshade (Solanum ptycanthum), but only 70% to 76% control of velvetleaf (Abutilon theophrasti), common ragweed (Ambrosia artemisiifolia), and common lambsquarters (Chenopodium album). The combination of sulfentrazone + dimethenamid-p provided good to excellent control of all weed species except velvetleaf. Based on this study, sulfentrazone and dimethenamid-p have potential for minor use registration in pepper.

Styles APA, Harvard, Vancouver, ISO, etc.

42

Afonin, A. N., O. G. Baranova, Y. A. Fedorova, L. M. Abramova, T. F. Boshko, N. V. Kotsareva, Yu S. Li et al. « ECOLOGICAL AND GEOGRAPHICAL POTENTIAL OF <i>AMBROSIA ARTEMISIIFOLIA</i> ; L. DISTRIBUTION TO THE NORTH OF THE EUROPEAN RUSSIA BASED ON A COMPARISON OF THE NORTHERN BOUNDARIES OF THE PRIMARY AND SECONDARY RANGES ». Russian Journal of Biological Invasions 15, n^o 1 (24 février 2022) : 2–12. http://dx.doi.org/10.35885/1996-1499-15-1-2-12.

Texte intégral

Résumé :

During the expeditionary research, we specified the modern actual border of naturalization of in the European territory of Russia. This border passes through Kursk Region, as well as the north of Voronezh and Saratov regions. The total length of the expeditionary routes was around 8900 km with 777 locations surveyed. In order to identify the potential for its further spread to the north we performed comparative ecological and geographical analysis and modeling of the ragweed distribution in the north of its secondary range in the European Russia and in the primary range in Canada. Insufficient heat supply during the seed ripening period is the main factor limiting the spread of ragweed to the north. To determine the ecological and geographic niche of ragweed, we compiled a global map of the distribution of accumulated degree days above 10 °C for the period from the transition of the day length under 14 hours to the stable frosts in autumn (ADDfp). The ADDfp values were determined at the northernmost points of naturalization of in the European Russia and in Canada. Comparison of the ecological and geographical boundaries regarding the heat supply in the European Russia and in Canada showed that the ecological and geographical niche realized by ragweed in the North America is now generally wider than the one on the European Russia. We considered the possible reasons for the under-occupation of a potential ecological niche in the European Russia and made assumptions about the possibility of its further spread to the north. Regarding the factor of heat supply in the European Russia, ragweed can spread further to the north - in Bryansk, Oryol, Lipetsk, Tambov, Saratov, Orenburg regions, southern half of Penza Region, the south of Ulyanovsk and Samara regions and Bashkortostan. Additional difficulties with the species’ distribution in the northeastern direction in the European Russia can be attributed to an adverse effect of an additional factor: insufficient moisture supply, since in the Saratov Region and to the east ragweed is in the ecological pessimum simultaneously in terms of heat and moisture supply at its northern limit of distribution.

Styles APA, Harvard, Vancouver, ISO, etc.

43

Song, Jong-Seok, Ji-Hoon Im, Jin-Won Kim, Dong-Gil Kim, Yeonhwa Lim, Min-Jung Yook, Soo-Hyun Lim et Do-Soon Kim. « Modeling the Effects of Nitrogen Fertilizer and Multiple Weed Interference on Soybean Yield ». Agronomy 11, n^o 3 (10 mars 2021) : 515. http://dx.doi.org/10.3390/agronomy11030515.

Texte intégral

Résumé :

Understanding the effects of nitrogen (N) fertilizer on soybean-weed competition is essential for establishing a practical tool for N application and weed management. A two-year field experiment was conducted in a soybean field located in Bogatyrka (43.82° N, 131.6° E), Primorsky krai, Russia, to investigate the effects of N fertilizer and multiple-weed interference on soybean (Glycine max) yield and to model these effects. Soybean yield loss caused by the interference of multiple weeds including common ragweed (Ambrosia artemisiifolia), barnyard grass (Echinochloa crus-galli), and American slough grass (Beckmannia syzigachne) at different levels of N fertilizer was accurately described by a combined model incorporating inverse quadratic and exponential models into the rectangular hyperbolic model for two parameters Y0 and β, respectively. The combined model used in our study indicated that the application of N up to 36 kg N ha−1 can increase weed-free soybean yield by 2.2 Mg ha−1 but soybean yield under multiple-weed interference can sharply decrease with increasing total density equivalent, particularly at 36 kg N ha−1. These results, including the combined model, thus can support decision making for weed management under different N uses in soybean cultivation.

Styles APA, Harvard, Vancouver, ISO, etc.

44

Smith, Andrea, Nader Soltani, Allan C. Kaastra, David C. Hooker, Darren E. Robinson et Peter H. Sikkema. « Isoxaflutole and metribuzin interactions in isoxaflutole-resistant soybean ». Weed Science 67, n^o 05 (26 juin 2019) : 485–96. http://dx.doi.org/10.1017/wsc.2019.25.

Texte intégral

Résumé :

AbstractHerbicide-resistant weeds are a growing concern globally; in response, new herbicide resistance traits are being inserted into crops. Isoxaflutole-resistant soybean [Glycine max (L.) Merr.] will provide a new mode of action for use in this crop. Ten experiments were conducted over a 2-yr period (2017, 2018) to determine herbicide interactions between isoxaflutole and metribuzin on soybean injury, weed control efficacy, and soybean yield on a range of soil types. Soybean leaf-bleaching injury caused by isoxaflutole was most severe at sites with higher levels of rainfall after application. Control of weed species with isoxaflutole (52.5, 79, and 105 g ai ha−1) and metribuzin (210, 315, and 420 g ai ha−1) differed by site based on amount of rainfall after application. At sites where there was sufficient rainfall for herbicide activation, isoxaflutole at all rates controlled common lambsquarters (Chenopodium album L.), Amaranthus spp., common ragweed (Ambrosia artemisiifolia L.), and velvetleaf (Abutilon theophrasti Medik.) >90%; metribuzin at all rates controlled Amaranthus spp. and witchgrass (Panicum capillare L.) >80%. Control of every weed species evaluated was reduced when there was limited rainfall after herbicide application. The co-application of isoxaflutole + metribuzin resulted in additive or synergistic interactions for the control of C. album, Amaranthus spp., A. artemisiifolia, A. theophrasti, Setaria spp., barnyardgrass [Echinochloa crus-galli (L.) P. Beauv], and P. capillare. Isoxaflutole and metribuzin can be an effective management strategy for common annual broadleaf and grass weeds in Ontario if timely rainfall events occur after herbicide application.

Styles APA, Harvard, Vancouver, ISO, etc.

45

Cho, S. E., J. H. Park, M. J. Park et H. D. Shin. « First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Ambrosia trifida in Korea ». Plant Disease 95, n^o 11 (novembre 2011) : 1480. http://dx.doi.org/10.1094/pdis-05-11-0422.

Texte intégral

Résumé :

Ambrosia trifida L., commonly known as giant ragweed, is native to North America and was introduced to Korea in the 1970s (3). It is now widely naturalized, and since 1999, has been designated as one of 11 ‘harmful nonindigenous plants’ by the Korean Ministry of Environment because of its adverse effects on native plants. Various strategies to eradicate this noxious weed have been tried without any success (3). In September 2009, powdery mildew infections of giant ragweed were found for the first time in Dongducheon, Korea, and specimens were isolated and deposited in the Korea University Herbarium (KUS-F24683). White mycelial and conidial growth was present mostly on adaxial leaf surfaces with sparse growth on abaxial leaf sides. Severely infected leaves were malformed. Slight purplish discoloration occurred on the leaves contiguous with colony growth. Mycelial colonies were conspicuous, amphigenous, and epiphytic with indistinct to nipple-shaped appressoria. Conidiophores were 80 to 180 μm long and produced two to five immature conidia in chains. Conidia were ellipsoid or doliiform, 28 to 38 × 16 to 24 μm, and lacked distinct fibrosin bodies. Chasmothecia were amphigenous, scattered or partly clustered, dark brown, spherical, 95 to 130 μm in diameter, and contained 6 to 16 asci. Appendages were mycelioid, numbering 10 to 24 per chasmothecium, 0.5 to 2.5 times as long as the chasmothecial diameter, 1 to 4 septate, and were brown at the base and becoming paler toward the tip. Asci were short stalked, 50 to 75 × 32 to 42 μm and contained two spores. Ascospores were ellipsoid-ovoid with a dimension of 22 to 30 × 15 to 18 μm. On the basis of these morphological characteristics, this fungus was identified as Golovinomyces ambrosiae (Schwein.) U. Braun & R.T.A. Cook (= G. cichoracearum var. latisporus (U. Braun) U. Braun) (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from KUS-F24683 was amplified with the primers ITS5 and P3 and sequenced (4). The resulting sequence of 508 bp was deposited in GenBank (Accession No. JF907589) and was identical to the ITS sequences of G. ambropsiae on A. artemisiifolia var. elatior from Japan (AB077631) and Korea (JF919680) as well as on A. trifida from the United States (AF011292). Therefore, the sequence analysis verified the pathogen to be G. ambrosiae. To our knowledge, this is the first record of powdery mildew infections on giant ragweed outside of North America (2). Although the disease incidence is still low, the disease could be a limiting factor to suppress the expansion of this noxious weed in Korea. References: (1) U. Braun and R. T. A. Cook. Mycol. Res. 113:616, 2009. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , May 5, 2011. (3) S. M. Oh et al. Impacts of Invasive Alien Weeds and Control Strategies of Noxious Weeds in Korea. National Institute of Agricultural Science and Technology, Suwon, Korea, 2007. (4) S. Takamatsu et al. Mycol. Res. 111:117, 2009.

Styles APA, Harvard, Vancouver, ISO, etc.

46

Soltani, Nader, Christy Shropshire et Peter H. Sikkema. « Weed Control in Dicamba-Resistant Soybean with Glyphosate/Dicamba Applied at Various Doses and Timings ». International Journal of Agronomy 2020 (12 février 2020) : 1–6. http://dx.doi.org/10.1155/2020/8903941.

Texte intégral

Résumé :

Seven field trials were completed over a three-year period (2016 to 2018) in southwestern Ontario, Canada, to assess weed control in conventional-till dicamba-resistant (DR) soybean with glyphosate/dicamba (2 : 1 ratio) applied postemergence (POST) at 3 doses (900, 1350, and 1800 g·ae·ha−1) and 3 application timings (up to 5, 15, and 25 cm weeds). There was minimal soybean injury (≤2%) from treatments evaluated. Glyphosate/dicamba applied at application timing of up to 5, 15, and 25 cm weeds, controlled Amaranthus spp. (pigweed spp.) 87–96, 94–99, and 99%; Ambrosia artemisiifolia (common ragweed) 93–99, 97–99, and 99–100%; Chenopodium album (lambsquarters) 89–99, 95–100, and 99–100%; Echinochloa crus-galli (barnyardgrass) 81–84, 94–96, and 96–97%; Setaria faberi (giant foxtail) 37–90, 77–98, and 99–100%; and Setaria viridis (green foxtail) 94–96, 99, and 99–100%, respectively. Additionally, glyphosate/dicamba applied POST at 900, 1350, and 1800 g·ae·ha−1 controlled Amaranthus spp. 90–97, 95–98, and 97–99%; A. artemisiifolia 95–98, 97–99, and 99–100%; C. album 92–99, 95–100, and 98–100%; E. crus-galli 84–88, 93-94, and 95-96%; S. faberi 74–95, 75–97, and 79–98%; and S. viridis 98, 98–99, and 98–100%, respectively. Weed interference reduced DR soybean yield as much as 51% compared to the highest yielding treatments. Results indicate that glyphosate/dicamba applied POST at the label doses can provide an adequate control of troublesome weeds in DR soybean. Weed control was generally most consistent when glyphosate/dicamba was applied at the highest registered dose in Ontario (1800 g·ae·ha−1) and when weeds were up to 25 cm tall.

Styles APA, Harvard, Vancouver, ISO, etc.

47

Tamura, Yasumori, Makoto Hattori, Kotaro Konno, Yoshiaki Kono, Hiroshi Honda, Hiroshi Ono et Mitsuru Yoshida. « Triterpenoid and caffeic acid derivatives in the leaves of ragweed, Ambrosia artemisiifolia L. (Asterales : Asteraceae), as feeding stimulants of Ophraella communa LeSage (Coleoptera : Chrysomelidae) ». Chemoecology 14, n^o 2 (1 juin 2004) : 113–18. http://dx.doi.org/10.1007/s00049-004-0269-1.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

48

Morokhovets, T. V., V. N. Morokhovets, E. S. Markova, Z. V. Basay, S. S. Vostrikova et N. S. Skorik. « Phase sensitivity of some broad-leaved weed species to the herbicide Flex ». Siberian Herald of Agricultural Science 52, n^o 5 (30 novembre 2022) : 32–41. http://dx.doi.org/10.26898/0370-8799-2022-5-4.

Texte intégral

Résumé :

The effect of herbicide Flex, AS (active ingredient fomesafen 250 g/l) on annual weed species common in soybean crops was studied. The studies were conducted under greenhouse conditions in 2019-2021. The sensitivity of ragweed Ambrosia artemisiifolia L., Asian copper leaf Acalypha australis L., common lamb's quarters Chenopodium album L., common dayflower Commelina communis L., China jute Abutilon theophrasti Medik, trailing hollyhock Hibiscus trionum L., St.-Paul’swort Sigesbeckia pubescens Makino, green amaranth Amaranthus retroflexus L., elsholtzia Elsholtzia pseudocristata Levl. et Vaniot, and Siberian cocklebur Xanthium sibiricum Patrin ex Widd was determined. Weed treatment with Flex at rates of 0.75, 1.0, 1.25 and 1.5 l/ha was carried out three times a season at different stages of plant growth and development. The level of sensitivity of weed species to herbicide was judged by the decrease in height and weight of the aboveground organs of the experimental plants compared to the control. It was found that Flex herbicide completely destroys plants of all tested species in the early stages of growth and development (1-4 true leaves). When treating weeds that have formed 3-10 leaves, ragweed, green amaranth, Asian copper leaf, trailing hollyhock and Siberian cocklebur remain highly sensitive to the drug action (reduction of the aboveground weight up to 94-100%). Application of Flex on overgrown plants leads to a significant decrease in its activity against all studied weed species. When used in the third term, the herbicide is effective only on the green amaranth, suppressing the mass of the plants by 76-86%.

Styles APA, Harvard, Vancouver, ISO, etc.

49

Park, M. J., J. H. Park, S. H. Hong et H. D. Shin. « First Asian Report of Leaf Spot of Ambrosia trifida Caused by Septoria epambrosiae ». Plant Disease 96, n^o 2 (février 2012) : 289. http://dx.doi.org/10.1094/pdis-10-11-0845.

Texte intégral

Résumé :

Ambrosia trifida L., known as giant ragweed, is native to North America and was introduced in Korea in the 1970s (4). It is now widely naturalized, and since 1999, has been designated as one of 11 most ‘harmful nonindigenous plants’ by the Korean Ministry of Environment because of its adverse effects on native plants. Various strategies to eradicate this noxious weed have been unsuccessful (4). In June 2008, leaf spot symptoms on this weed were found in Inje, Korea. Hundreds of giant ragweed growing along stream banks contained leaf spots with leaf yellowing and premature defoliation. Leaf lesions were 1 to 5 mm in diameter, angular to irregular, dark brown without a distinct margin, later becoming pallid with a brown margin. Between 2008 and 2011, the authors observed the same symptoms in Dongducheon, Yangku, Namyangju, and Pocheon, Korea. Voucher specimens have been housed in the herbarium of Korea University. Numerous black pycnidia were formed on the lesion. Pycnidia were amphigenous, globose, dark brown, ostiolate, and measured 80 to 130 μm in diameter. Conidia were filiform, straight to mildly curved, eguttulate, hyaline, 18 to 36 × 1.5 to 2.5 μm, one to three septate, subtruncate at the base, and tapering to a rounded apex. Single-conidial isolations onto potato dextrose agar formed dark grayish colonies. Pycnidia matured after 5 weeks when plates were incubated under fluorescent illumination for 12-h photoperiods at 25°C. On the basis of morphological and cultural characteristics, the fungus was identified as Septoria epambrosiae D.F. Farr (2). Three isolates were deposited in the Korean Agricultural Culture Collection (KACC). Preliminary morphological identification of the fungal isolates was confirmed by molecular data. The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequences of 449 bp obtained from the three isolates were identical to each other. They showed 100% similarity when compared with a sequence of S. epambrosiae (GenBank No. AF279582). The nucleotide sequence of a representative isolate (KACC43850) was deposited in GenBank (No. JN695498). Pathogenicity was confirmed by inoculating the leaves of three seedlings with a conidial suspension (~2 × 105 conidia/ml). Three noninoculated seedlings served as controls. Plants were maintained in a glasshouse at 100% relative humidity for 48 h. After 6 days, typical leaf spots, identical to the one observed in the field, started to develop on the leaves of the inoculated plants. No symptoms were observed on the control plants. The fungus was successfully reisolated from the symptomatic plants, fulfilling Koch's postulates. A leaf spot disease associated with S. epambrosiae has previously been recorded on A. artemisiifolia in Hungary (1–3) and A. trifida in North America (2,3). To our knowledge, this is the first report of S. epambrosiae on giant ragweed in Asia. Because of its potential as a biocontrol agent, further studies are needed. References: (1) G. Bohar and I. Schwarczinger. Plant Dis. 83:696, 1999. (2) D. F. Farr and L. A. Castlebury. Sydowia 53:81, 2001. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , September 20, 2011. (4) S. M. Oh et al. Impacts of Invasive Alien Weeds and Control Strategies of Noxious Weeds in Korea. National Institute of Agricultural Science and Technology, Suwon, Korea, 2007.

Styles APA, Harvard, Vancouver, ISO, etc.

50

Vajna, L., G. Bohár et L. Kiss. « First Report of Phyllachora ambrosiae in Europe Causing Epidemics on Common Ragweed ». Plant Disease 84, n^o 4 (avril 2000) : 489. http://dx.doi.org/10.1094/pdis.2000.84.4.489a.

Texte intégral

Résumé :

Common ragweed (Ambrosia artemisiifolia var. elatior (L.) Descourt.) was introduced to Europe from North America during the nineteenth century. Since the early 1990s, it has become the most widespread and most important allergenic weed in Hungary. In July 1999, during the annual survey of fungal diseases of ragweed in Hungary, plants exhibiting irregular brown spots surrounded by yellowish halos with small black spherical bodies on the upper surface of leaves, especially along the vessels, were collected from three roadside sites. Light microscopy revealed intracellular hyphae in the cells of leaf tissues, including the vessels, and perithecia (186 to 262 μm in diameter) containing paraphyses and asci (93 × 15 μm) with eight hyaline, unicellular ascospores (14 × 7.5 μm). Hyphae also were observed in asymptomatic leaf tissues and the petioles of infected plants. Mature perithecia commonly found in the necrotic spots also were present in asymptomatic, green leaf tissues. Based on the literature (1,2) and on the morphological examination of two herbarium specimens, BPI 636220 and BPI 636225, borrowed from the U.S. National Fungus Collection, the fungus was identified as Phyllachora ambrosiae (Berk. & M.A. Curtis) Sacc., a holobiotrophic pathogen of ragweed in North and South America. This is the first report of P. ambrosiae on ragweed in Europe. To confirm pathogenicity, leaves of five potted ragweed plants, grown from seed in pots, were inoculated with 0.1 ml of an aqueous suspension containing 5 × 105 ascospores per ml. Inoculated plants were placed in a moist chamber for 48 h and kept in the greenhouse at 20 to 25°C. Noninoculated plants served as controls. Two weeks after inoculation, yellowish spots, which later became brown and necrotic, and perithecia appeared on each of the inoculated leaves. Infected leaves died 3 to 4 weeks after inoculation. Symptoms were similar to those seen in the field. The fungus in tissues of inoculated plants was morphologically identical to the original fungus on plants with spontaneous infections. Control plants did not develop symptoms. To determine the distribution of P. ambrosiae in Hungary, a total of 500 ragweed plants were collected at random from 21 locations in all regions of the country between August and October 1999. Symptoms characteristic of P. ambrosiae infections and perithecia of the fungus were found in 92% of all 500 collected plants. From mid-September, all ragweed plants examined had dead leaves and inflorescences. Perithecia of P. ambrosiae were found in leaves, stems, and flowers. References: (1) P. A. Saccardo. 1883. Sylloge Fungorum. Patavii (Padova), Sumptibus Aucteris. (2) F. Theissen and H. Sydow. 1915. Ann. Mycol. 13:431.

Styles APA, Harvard, Vancouver, ISO, etc.

Articles de revues sur le sujet « Ambrosia artemisiifolia, Amb a 1, ragweed »

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres