Submitted by Biblioteca da Faculdade de Farmácia (bff@ndc.uff.br) on 2017-03-17T19:14:35Z No. of bitstreams: 1 Ribeiro, Anézia Lima Chaves [Dissertação, 2011].pdf: 3144917 bytes, checksum: 028a1b168bde80a2bfe9b881b9c28b08 (MD5) / Made available in DSpace on 2017-03-17T19:14:35Z (GMT). No. of bitstreams: 1 Ribeiro, Anézia Lima Chaves [Dissertação, 2011].pdf: 3144917 bytes, checksum: 028a1b168bde80a2bfe9b881b9c28b08 (MD5) / O glifosato é um herbicida organofosforado amplamente utilizado que constitui um poluente potencial do meio ambiente; ácido aminometilfosfônico (AMPA) é o seu principal metabólito. O objetivo deste estudo foi desenvolver um método direto rápido e sensível para a quantificação dos herbicidas, a fim de monitorar seus resíduos na água de diferentes fontes. Além disso, este estudo teve como objetivo elaborar um procedimento para a determinação simultânea de glifosato, AMPA e F-, Cl-, Br-, NO3 -, SO4 2- e PO4 3- na água. Em ambos os casos, foram usados a cromatografia de troca iônica com detecção condutométrica. A determinação de glifosato pode ser realizada em modo isocrático (6,0 mmol L-1 Na2CO3 e 2,0 mmol L-1 NaHCO3), enquanto a separação simultânea de glifosato, AMPA e ânions foi realizada por gradiente com as seguintes fases móveis: A: 15,0 mmol L-1 NaOH + 1,0 mmol L-1 Na2CO3 e B : Na2CO3 - 15,0 mmol L-1. A confirmação de espécies AMPA (m / z = 110) e glifosato (m / z = 168) foi realizada pelo IC-MS. A determinação do isótopo 31P por ICPMS permitiu a determinação indireta destas espécies e um teste de recuperação resultou em cerca de 105%. O método foi validado utilizando matrizes de agua ultrapura, agua superficial, mineral e água subterrânea. Por eluição isocrática, os limites de detecção (LODs) encontrados para o glifosato foram: 10 μgL-1 em água ultrapura , 54 μgL-1 em água subterrânea. Para a determinação simultânea de glifosato e AMPA, os LODs foram: 9,6 μgL-1 , 9,8 μgL-1 (água ultrapura), 9,5 μgL-1 , 60 μgL-1 (água mineral), 12,4 , 29,7 μgL-1 (agua superficial) respectivamente para glifosato e AMPA. A determinação de glifosato por IC/Condutimetria mostrou-se adequada à aplicação em águas naturais, alcançando valores de LD muito abaixo dos permitidos pela legislação vigente (500 μgL-1; Portaria MS 518 de 25/03/2004 e Resolução CONAMA 396 de 03/04/2008) e, também outros órgão internacionais como EPA, sem necessidade de preparação prévia da amostra como extração, pré-concentração e derivatização / Glyphosate is a widely used organophosphorated herbicide, which constitutes a potential pollutant of the environment; aminomethylphosphonic acid (AMPA) is its main metabolite. The purpose of this study was to develop a direct, rapid and sensitive method for quantification of the herbicide in order to monitor its residues in water from different sources. Furthermore, this study aimed to draw up a procedure for the simultaneous determination of glyphosate, AMPA and F-, Cl-, Br-, NO3 -, SO4 2- and PO4 3- in water. In both cases, ion-exchange chromatography with conductimetric detection were used. The determination of glyphosate could be performed in isocratic mode (6.0 mmol L-1 Na2CO3 and 2.0 mmol L-1 NaHCO3), while the simultaneous separation of glyphosate, AMPA and anions was performed by gradient elution with the following mobile phases: A - 15.0 mmol L-1 NaOH + 1.0 mmol L-1 Na2CO3 and B - 15.0 mmol L-1 Na2CO3. Confirmation of species AMPA (m/z = 110) and glyphosate (m/z = 168) were carried out by IC-MS. The determination of the isotope 31P by ICPMS allowed the indirect determination of these species and a recovery test resulted in about 105%. The method was validated using ultrapure, river, mineral and groundwater. With isocratic elution, limits of detection (LODs) of 10 μg L-1 in ultrapure water and 54 μg L-1 in groundwater were found for glyphosate. For the simultaneous determination of glyphosate and AMPA, LODs were, respectively, 9.6 μg L-1, 9.8 μg L-1 (ultrapure water), 9.5 μg L-1, 60 μg L-1 (mineral water), 12.4 μg L-1, 29.7 μg L-1 (river water). The determination of glyphosate IC / Conductimetry proved to be suitable for application in natural waters, reaching LD values far below those allowed by legislation (500 μg L-1), MS portaria 518 of 25/03/2004 and CONAMA Resolution 396 of 03 / 04/2008), and also other international bodies such as EPA, without previous sample preparation and extraction, pre-concentration and derivatization

Pesticide testing is of practical interest in various areas of today’s world due to their prevalence and toxicity. These areas include agriculture, environmental, chemical plants, and many others. Herbicides, like Roundup, contain secondary amines such as glyphosate. The ability to detect secondary amines could offer a method for glyphosate detection in agricultural and environmental samples. Secondary amines can interact with metal complexes through electron charge transfer. Such interactions can cause a change in the metal’s electron configuration and energy state and can be seen in the UV-Vis spectrum. Metal phthalocyanines (MPc’s) and other organometallic complexes have been of interest for these reasons and may be applicable to glyphosate detection without extensive laboratory tests. UV-Vis absorption can further provide quantitative measurements. An evaluation of FeTSPc’s ability to aid in remediation via adsorption supports was also examined.

No description available.

Research was conducted in 2013 and 2014 to evaluate the postemergence control of Palmer amaranth [Amaranthus palmeri (S.) Wats.] with mesotrione alone and in mixtures with fomesafen and/or glyphosate and to evaluate the impact of lactofen and planting date on growth, development, and yield of indeterminate soybean [Glycine max (L.) Merr.]. Studies included a greenhouse evaluation of different rates of mesotrione on the control of 5- and 10-cm Palmer amaranth and field studies evaluating the control of 5- to 10-cm Palmer amaranth with three rates of mesotrione applied alone and in mixtures with fomesafen and/or glyphosate. Lactofen studies include a planting date study evaluating one rate of lactofen applied at V2 soybean stage with planting dates of April 15, May 1, May 15, and June 1 and a lactofen timing study where one rate of lactofen was applied at soybean growth stages ranging from V1 to R5.

Tomato is a major horticulture crop grown across the globe. Unfortunately, its yield is reduced by 25% because of auxin herbicides and glyphosate drift. In this present study, wild germplasm of tomato was screened for herbicide tolerance. From the greenhouse study nine accessions for glyphosate and 2,4-D, eleven accessions for dicamba, five accessions for quinclorac, eight accessions for aminocyclopyrachlor, and two accessions for picloram and aminopyralid were identified to be tolerant. A few accessions were selected from each herbicide tolerant group for field trials at two locations in Mississippi in 2016 and 2017. Results indicated that TOM18 was most tolerant to dicamba herbicide, while TOM87 and TOM129 to glyphosate and quinclorac herbicide, respectively, on the basis of yield and injury. Molecular experiments were conducted to measure the genetic diversity among diverse germplasm. Genetic diversity analysis showed wild accessions to be highly diverse as compared to cultivated tomato.

Dicamba is often tank mixed with glyphosate to increase herbicidal efficacy but may contribute to off-target movement (OTM). In recent years, volatilization has become problematic for dicamba-containing herbicides, resulting in increased regulatory requirements necessitating the use of volatility-reducing agents (VRA) for application. Research was conducted in 2021 and 2022 using low tunnels in a field environment and humidomes in a greenhouse environment to further assess how glyphosate salts and VRAs affect dicamba volatility. Our data indicate that the inclusion of glyphosate to dicamba can increase dicamba volatility, depending on the glyphosate salt used. The inclusion of the evaluated VRAs will decrease dicamba volatility when applied to a tank mixture of dicamba plus potassium salt of glyphosate.

Microstegium vimineum, or Japanese stilt grass, is an invasive species that readily outcompetes native vegetation and is of poor forage quality for wildlife. This species is widespread throughout the southeastern United States, including North Carolina. Much of this region is privately owned and there is a gap in the literature providing succinct information about the best methods of treatment, timing of treatment, and effects of treatment on native herbaceous plants in this region. In two parts, this study seeks to address this gap by employing treatments that are easily accessible to landowners at different times during the growing season and assessing the effects on the herbaceous plant community post-treatment. Results of this study found that application of glyphosate was the most effective treatment at M. vimineum removal, application of household vinegar was the most effective at increasing post-treatment species richness and diversity, and that seasonality did not play a role in the effectiveness of treatment options. This study will increase landowner knowledge on treating this invasive successfully and choosing a treatment that fosters an understory that meets their management goals.

Research was conducted at the Mississippi State University Delta Research and Extension Center from 2016 to 2018 to determine the effects of sub-lethal concentrations of paraquat, glyphosate, saflufenacil, and sodium chlorate exposure to rice at late-season growth stages, determine the effects of exposure to sub-lethal concentrations of glyphosate or paraquat on multiple rice cultivars, and characterize the effects of paraquat exposure and Oebalus pugnax feeding on rice grain quality. In the current research, rough rice grain yields were reduced by exposure to sub-lethal concentrations of soybean desiccants 0 to 28 DAH. Rice injury was determined to not be an accurate predictor of rough rice grain yield loss as injury did not exceed 20% with any desiccant, and no injury was observed from glyphosate applications. Rough rice grain yield reductions were reflected in yield component reductions following desiccant exposure. Applications of sub-lethal concentrations of glyphosate or paraquat to rice at 50% heading caused rough rice grain yield decreases ranging from 0 to 20 and 9 to 21 % respectively. Hybrid cultivars were unaffected following glyphosate exposure at 50% heading. In the current research, observations of paraquat exposure or O. pugnax infestation of rice at the soft dough growth stage suggest rice may exhibit severe sensitivity to both events in the form of reduced kernel weight and reductions in rice milling quality. Rough rice grain yield reductions coupled with milling quality reductions and driven by the proximity of rice to corn, cotton, soybean, and sorghum in Mississippi creates the need to exercise caution when applying desiccants.

No description available.

Glyphosate resistant crops were rapidly adopted by farmers since their introduction in 1996 and currently, greater than 90% of cotton and soybean crops are glyphosate resistant. Glyphosate has been an effective mean for controlling Palmer amaranth, however overreliance on glyphosate based systems resulted in weeds that can no longer be controlled with glyphosate. Palmer amaranth resistance to glyphosate has been confirmed in ten US states including Virginia's bordering neighbor North Carolina. The objectives of this study were to i) determine the spread of Palmer amaranth and evaluate awareness among farmers and agribusinesses of herbicide resistant weeds in Virginia; ii) determine the efficacy of commonly used cotton and soybean herbicides programs for Palmer amaranth control; and iii) conduct greenhouse experiments to quantify the level of glyphosate resistance in a Greensville County, Virginia population. Using a communication network of Virginia county extension agents and crop advisers, Palmer amaranth was found in 15 Virginia counties. A survey was conducted to evaluate awareness of herbicide resistance and management of weeds in Virginia. Ninety percent of producers had fields planted to Roundup Ready® crops for each of the last 3 years. One hundred percent of the responders claimed awareness of the potential for weeds to develop resistance to glyphosate, but when asked about how serious they consider weed resistance to herbicides, the responders average rating was of 7.9 (on a scale of 1 to 10 where 1 is "not at all serious" and 10 is "very serious" ). Eighteen percent of the responder population claimed no awareness of glyphosate resistant weeds documented in Virginia. Herbicide efficacy experiments were established in soybean and cotton fields infested with Palmer amaranth. In soybean, experiments were established in a field where Palmer amaranth was not adequately controlled with glyphosate in the previous year. Glyphosate applied at 0.87 + 0.87 + 1.74 kg ae ha⁻¹ at 1, 3, and 5 weeks after planting (WAP) provided 82 to 85% control in 2009, but only 23 to 30% control in 2010, a hot and dry year. Glyphosate applied after preemergence (PRE) herbicides improved control to 90 percent. Programs that included s-metolachlor + metribuzin applied preemergence and followed by glyphosate + fomesafen applied postemergence provided the best control (93%) at 8 WAP. Glufosinate based herbicide programs provided greater than 85% control when applied alone, and control increased to 95% when preceded by PRE herbicides. Many conventional control systems integrating different modes of action provided more than 80% control at final evaluation of Palmer amaranth in 2009 and 2010. In soybean, the most consistent and effective program was flumioxazin applied PRE followed by chlorimuron + thifensulfuron, which provided 99 and 82% control at final evaluation in 2009 and 2010, respectively. Cotton fields were heavily infested with Palmer amaranth, but control with glyphosate had historically been good. Glyphosate applied early postemergence, late postemergence, and late post-directed provided more than 95 percent control at final evaluation of Palmer amaranth. Preemergence applications of fomesafen, fluometuron, or pendimethalin + fomesafen provided 77 to 99 percent early-season control and control was complete with an additional postemergence glyphosate application. Glufosinate applied at 0.45 kg ha⁻¹ at 1 and 3 WAP or applied at 0.45 kg ha⁻¹ following a preemergence herbicide provided greater than 95% control. Greenhouse experiments confirmed Palmer amaranth resistance in a population collected from Greensville County, Virginia. In the first experiment, the resistant biotype's I₅₀ value (rate necessary for 50% inhibition) for dry weight was 1.47 kg ae ha⁻¹, which is 4.6 times greater than the susceptible biotype and 1.7 times the recommended use rate of glyphosate. For fresh weight, the I₅₀ value of the resistant biotype was 1.60 kg ae ha⁻¹, 4.7 times that of the susceptible biotype of 0.34 kg ae ha⁻¹. In the second experiment, the I₅₀ value for the susceptible population could not be determined because all glyphosate rates resulted in complete control. However, the resistant population required 1.01 and 1.30 kg ae ha⁻¹ of glyphosate to reduce the fresh and dry weight by 50%. / Master of Science