Amount Of Glyphosate Research Articles

Features of analytical control of glyphosate salts in preparative formulations

Goal. Development of a method of analytical control of glyphosate in preparative forms of herbicides.
 Methods. Determination of glyphosate was carried out by the chromatographic method of thin-layer chromatography (TLC) using Sorbfil plates with a thin layer of silica gel KSK adsorbent. The active substance was identified by the value of Rf, quantitative determination was based on the formalized dependence of the size of the area of the chromatographic zones on the amount of glyphosate.
 Results. Physicochemical properties of herbicides — electrolytes, to which glyphosate belongs, create special problems when developing methods for its determination in various matrices. In herbicides and desiccants, glyphosate (as a salt) usually takes the form of a deprotonated acid residue and a corresponding cation. Therefore, the determination of the active substance is carried out by the acid residue, which is important for the quantitative assessment of its content in the matrix both in the acid equivalent and in the form of the corresponding salt. The density of the preparative form serves, in particular, as a criterion for controlling the form of the glyphosate salt. The method is based on dissolution of the preparation form in 44% ethanol and quantitative determination by TLC method. The determination of the active substance is not hindered by other components of the preparations, derivatives of glycine and amines.The optimal conditions of analysis were chosen using the conceptual designs of the laboratory «Algorithm of chemical-analytical monitoring of pesticides» and «System of multi-quantitative determination of pesticides in matrices», according to which the main stages of the process are extraction/dissolution, purification of extracts, elution (chromatographic process), identification and quantitative analysis . Selective conditions for TLC determination — mobile phase with pH 9: distilled water + ethanol + aqueous ammonia (22 + 20 + 0.25 by volume), developing reagent: a specific complex of ninhydrin with cadmium acetate in an acidic medium. Quantitative determination is carried out taking into account the coefficients of conversion of the corresponding salt form to the acid equivalent.
 Conclusions. The use of the chromatographic method of thin-layer chromatography makes it possible to control the content of the active substance glyphosate in various salt formulations in preparative forms of herbicides and desiccants with high accuracy and reproducibility.

Effects of glyphosate and glyphosate‐based herbicide on learning and memory of the buff‐tailed bumblebee (Bombus terrestris)

AbstractThe decline of insect pollinators is a global concern, and the use of pesticides has been identified as a potential cause for it. Glyphosate‐based herbicides (GBHs) are the world's most used pesticides, but until recent years they have been claimed to be safe for non‐target organisms, such as pollinators. Using controlled arena experiments, we investigated the effects on the learning and long‐term memory of buff‐tailed bumblebees, Bombus terrestris (L.) (Hymenoptera: Apidae), of a single field‐realistic dose of glyphosate, both in its pure form and as a commercial herbicide (Roundup Gold) containing the active ingredient (a.i.) glyphosate and other co‐formulants. We found that glyphosate in its pure form caused deterioration in the learning ability of bumblebees in a 10‐color discrimination experiment; the glyphosate‐treated bees discriminated colors over 10% worse than the untreated control bees. However, the commercially used GBH (Roundup Gold) had no observable effect on the learning ability of the bumblebees, despite the fact that this herbicide contained the same amount of glyphosate as its pure form. These findings shed light on the potential risks associated with agrochemicals previously considered safe for pollinators and emphasize the need for comprehensive risk assessments of pesticides, including evaluations of cognitive functions in pollinators. Therefore, we propose that future pesticide testing should incorporate broader assessments to ensure the safety of pollinators in agricultural landscapes.

Agnes Rimando, a Pioneer in the Fate of Glyphosate and Its Primary Metabolite in Plants.

Glyphosate is the most used herbicide on the planet because of its excellent efficacy on almost all weed species and due to the large-scale adoption of transgenic, glyphosate-resistant (GR) crops. Agnes Rimando became an expert in glyphosate analysis almost 20 years ago to support research on GR crop safety and on mechanisms of evolved glyphosate resistance by weeds. Her work was the first to show that the amount of glyphosate and its primary metabolite aminomethylphosphonic acid (AMPA) that accumulates in GR soybean seed from plants treated with approved glyphosate doses can approach their legal limits. However, she later found that only trace amounts of these compounds accumulate in the seed of GR maize treated with recommended glyphosate doses. She showed that GR canola, the only transgenic crop with a transgene encoding an enzyme for degradation of glyphosate, metabolizes glyphosate to AMPA very rapidly. Her work was instrumental in providing support for the view that "yellow flash" symptoms sometimes observed in field-grown GR soybeans are due to accumulation of enough AMPA to cause mild phytotoxicity. She did the chemical analyses in the only paper to survey the capacity of an array of plant species to metabolize glyphosate to AMPA. She found a wide range in this capacity, with grasses with little or no metabolism of glyphosate to AMPA and with legumes readily metabolizing glyphosate. Lastly, she found no evidence of enhanced degradation of glyphosate to be a mechanism of evolved resistance to glyphosate by two weed species but that it might be involved in natural tolerance to glyphosate of some weeds.

The First Case of Glyphosate Resistance in Johnsongrass (Sorghum halepense (L.) Pers.) in Europe.

Six Johnsongrass populations suspected of being glyphosate resistant were collected from railways and freeways near Cordoba (SW Spain), where glyphosate is the main weed control tool. The 50% reduction in shoot fresh weight (GR50) values obtained for these six populations ranged from 550.4 to 1169 g ae ha−1, which were 4.2 to 9 times greater than the value obtained for the susceptible population. Glyphosate was equally metabolized to the same extent in both resistant and susceptible populations, with no significant differences in either 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibition or basal activity. No amino acid substitutions were observed in any of the resistant populations. Slight but significant differences in glyphosate penetration were observed among some but not all of the resistant populations and for the times of incubation assayed, although these differences were not considered further. The proposed primary mechanism of resistance in these six glyphosate-resistant Johnsongrass populations is reduced herbicide translocation, because the amount of glyphosate that translocated from treated leaves to shoots and roots in the susceptible population was double that observed in the resistant populations. As glyphosate multiple resistance due to more than one mechanism is not uncommon, this is the first time that glyphosate-resistant Johnsongrass populations have been fully described for all known mechanisms.

Modeling the mobility of glyphosate from two contrasting agricultural soils in laboratory column experiments

Glyphosate (GLP) currently is one of the most widely used herbicides worldwide. The persistence of GLP and its major metabolite, aminomethylphosphonic acid (AMPA) in the environment has been described by other authors. This study was aimed at comparing the GLP and AMPA behavior in sandy and loamy sand soils after spiking with enhanced (445 µg g−1) concentrations of GLP in herbicide KLINIK® (Nufarm, Austria) and bioaugmentation followed by 40 days weathering and a consistent three-stage leaching in a laboratory column experiment. Soil samples were obtained from mineral topsoil (0–10 cm) within former agricultural lands where soil parent material was formed by glacigenic deposits. The total amount of GLP and AMPA collected during three leaching stages was significantly (p<.05) higher from columns with sandy soil, compared to loamy sand soil. Bioaugmentation resulted in considerably lower concentrations of AMPA in leachates, especially in the sets with sandy soil (p=.01). Leachates were tested using FTIR spectroscopy and Daphnia magna. Statistical analysis of the changes in Ntot, Ctot, K+, Mg2+, Al3+, Ca2+, Mn2+ and Fe3+ concentrations in soils after the leaching experiment revealed that the loamy sand soil was likely to be more sensitive to the addition of GLP and bioaugmentation than sandy soil.

Polyaniline/FeZSM-5 composites – Synthesis, characterization and their high catalytic activity for the oxidative degradation of herbicide glyphosate

Semiconducting composites of nanostructured and granular polyaniline (PANI) with FeZSM-5 zeolite were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in water, without added acid and in an aqueous H2SO4 solution, in the presence of FeZSM-5, by using initial weight ratios aniline/FeZSM-5 of 1/1 and 1/5. These novel composite materials, in their as-synthesized (protonated) and deprotonated forms, were characterized by elemental, thermogravimetric and differential thermal analysis, scanning electron microscopy, FTIR and Raman spectroscopy, X-ray powder diffraction and conductivity measurements. The catalytic activity of the PANI/FeZSM-5 composites towards the oxidation of herbicide glyphosate with hydrogen peroxide has been investigated. A significant improvement of the catalytic activity of PANI/FeZSM-5 composites compared to that of pure PANI and FeZSM-5 was observed, manifested by the almost one order of magnitude more efficient oxidative degradation of glyphosate with hydrogen peroxide. The maximum of oxidized/decomposed amount of glyphosate was achieved in the presence of PANI/FeZSM-5 composite synthesized using an initial aniline/FeZSM-5 = 1/5 wt ratio. It has been shown that the method of synthesis and interactions between PANI and zeolite in this complex composite system, leading to more efficient electron transfer and hydrogen peroxide decomposition, are crucial for the catalytic properties of tested PANI/FeZSM-5 materials. It is shown that new PANI/FeZSM-5 composites present advanced catalyst materials for enhanced green catalytic degradation of pesticide/herbicide pollutants in environmental remediation systems.

Glyphosate dose modulates the uptake of inorganic phosphate by freshwater cyanobacteria

The usefulness of glyphosate [N-(phosphonomethyl)glycine] as a source of nutritive phosphorus for species of halophilic cyanobacteria has been postulated for years. Our results indicate a stimulating effect of glyphosate on the growth of four out of five examined freshwater species, Anabaena variabilis (CCALA 007), Chroococcus minutus (CCALA 055), Fischerella cf. maior (CCALA 067) and Nostoc cf. muscorum (CCALA 129), in a manner dependent on the applied concentration. The most significant stimulation was observed at a dose of 0.1 mM glyphosate. The decrease in the amount of phosphonate, which correlated with microbial growth, demonstrated that glyphosate may play an important role in cyanobacterial nourishment. Surprisingly, the consumption of organic phosphorus did not start when concentrations of inorganic phosphate (PO43−) had fallen dramatically; instead, the assimilation of both types of phosphorus occurred simultaneously. The greatest decrease in the amount of glyphosate was observed during the first week. The uptake of the standard nutrient-phosphate (PO43−), was strongly dependent on the xenobiotic concentration. When a concentration of 0.1 mM glyphosate was used, the consumption of phosphate decreased in favour of glyphosate assimilation. Our study revealed for the very first time that the presence of inorganic phosphate significantly enhances the bioavailability of glyphosate. Statistical analysis confirmed that the nutritive usage of glyphosate and the absorption of phosphate are features associated with the herbicide concentration rather than features related to the species of freshwater cyanobacterium. This finding supports the thesis of an important role of organic phosphorus in the formation of cyanobacterial blooms and creates the opportunity of using these cyanobacteria to bind both organic and inorganic forms of phosphorus in microalgal biomasses.

Degradation Dynamics of Glyphosate in Different Types of Citrus Orchard Soils in China

Glyphosate formulations that are used as a broad-spectrum systemic herbicide have been widely applied in agriculture, causing increasing concerns about residues in soils. In this study, the degradation dynamics of glyphosate in different types of citrus orchard soils in China were evaluated under field conditions. Glyphosate soluble powder and aqueous solution were applied at 3000 and 5040 g active ingredient/hm2, respectively, in citrus orchard soils, and periodically drawn soil samples were analyzed by high performance liquid chromatography. The results showed that the amount of glyphosate and its degradation product aminomethylphosphonic acid (AMPA) in soils was reduced with the increase of time after application of glyphosate formulations. Indeed, the amount of glyphosate in red soil from Hunan and Zhejiang Province, and clay soil from Guangxi Province varied from 0.13 to 0.91 µg/g at 42 days after application of aqueous solution. Furthermore, the amount of glyphosate in medium loam from Zhejiang and Guangdong Province, and brown loam from Guizhou Province varied from less than 0.10 to 0.14 µg/g, while the amount of AMPA varied from less than 0.10 to 0.99 µg/g at 42 days after application of soluble powder. Overall, these findings demonstrated that the degradation dynamics of glyphosate aqueous solution and soluble powder as well as AMPA depend on the physicochemical properties of the applied soils, in particular soil pH, which should be carefully considered in the application of glyphosate herbicide.

Synthesis of Alkyl Polyglycoside and its Application in the Glyphosate

Using sweet potato starch, butanol, and dodecyl alcohol as raw materials, the alkyl indican surfactant was synthesized by two-step reactions with composite catalysts of p-toluene sulfonic acid and citric acid, the synthesis conditions were investigated through orthogonal method and the structure of the product was characterized by IR and mass spectroscopy. The weeding test was also studied by adding the appropriate proportion of alkyl indican surfactant. The results showed that the best technological conditions was: reaction took place under 120 C and last for 4 h, msweet potato starch:mn-butanol: mn-dodecanol=msp:mnb:mnd=1:2:5, the content of composite catalysts was 1.6 wt% p-toluene sulfonic acid and 10.0 wt% citric acid. The weeding test demonstrated that added 1% APG into the glyphosate could killed almost all weeds in five days and had an excellent weeding efficiency. Compared with spraying glyphosate with no APG, which could decrease the amount of glyphosate used and protect the environment.

Dissipation of Glyphosate Injected into the Lead Tree (Leucaena leucocephala) in Different Seasons in Taiwan

To determine the appropriate way to control the lead tree (Leucaena leucocephala (Lam) de. Wit), an invasive plant in Taiwan, 3 concentrations with an equal amount of glyphosate (18.8 mmole) were applied in spring and summer, respectively, and glyphosate residues in the plants and soils were monitored. A good control effect was observed with injecting a commercial product of glyphosate without dilution, especially in spring. Measurements of glyphosate residues in the upper (25 cm above the upper injection hole), middle (between the 2 injection holes), and lower (25 cm below the lower injection hole) parts of the lead tree, as well as in forest soils in spring and summer experiments showed that this herbicide began to sharply dissipate after treatment, which was accelerated by high temperatures and heavy rainfall from typhoons. In the spring experiment, it required ca. 1 yr for glyphosate residues in both the lead trees and soils to drop to a few parts per million, while this period was further shortened in the summer experiment. Thus, there is only a small possibility of glyphosate pollution of the soil environment of lead tree forests. Analysis of glyphosate in xylem and phloem from different parts of the plants revealed that after injection, glyphosate gradually diffused acropetally, basipetally, and laterally from the xylem tissue to the surrounding phloem tissue. Glyphosate appeared to preferentially diffuse to and accumulate in phloem near the injection hole for further long-distance translocation in phloem tissue.

Interaction of Glyphosate and Diquat in Ready-To-Use Weed Control Products

Glyphosate-based, ready-to-use weed control products frequently contain diquat (typically, 0.04 by weight relative to glyphosate) under the supposition that the diquat, “makes glyphosate work faster.” However, in light of the known modes of actions of glyphosate and diquat, we hypothesize that diquat may be antagonistic to glyphosate activity. Greenhouse experiments using longstalked phyllanthus were conducted to test this hypothesis. Glyphosate was applied at a series of rates, ranging from 0.11 to 1.12 kg ae/ha, either alone or tank-mixed with either 0, 0.02, 0.04, and 0.06 diquat. Onset of visual injury was more pronounced with the glyphosate + diquat tank mixtures compared with glyphosate alone. However, long-term control, as expressed by regrowth suppression, was greater with glyphosate alone. Regression analysis indicated that, at marginally effective glyphosate rates, the amount of glyphosate must be increased by approximately 60% to compensate for the diquat-based antagonism. Absorption and translocation studies using 14C-glyphosate revealed that the antagonism of diquat toward glyphosate can be attributed to reduced translocation of absorbed glyphosate.

Effect of Phosphate on the Adsorption of Glyphosate on Soils, Clay Minerals and Oxides

The effect of phosphate (ortho-phosphate) on the adsorption of the widely used glyphosate herbicide was evaluated with three typical Danish agricultural soils as well as pure oxides (goethite, FeOOH and gibbsite, Al(OH) 3 ) and silicates (illite and montmorillonite), which are considered the most important glyphosate and phosphate adsorbents in soils. Batch experiments where made in order to find out how phosphate affects adsorption of glyphosate and how glyphosate affects adsorbed phosphate. Solution glyphosate was quantified by liquid scintillation counting of 14 C-taggered herbicide and the concentration of phosphate by the molybdenum blue method. All experiments showed competition between phosphate and glyphosate for adsorption sites but the various adsorbents exhibited great variation in affinity for glyphosate and phosphate. Thus, gibbsite and, in particular goethite strongly prefer phosphate, whereas the competition on the silicates is more equal. The current studies showed that the competition in soils is almost equal, but still phosphate affects the sorption of glyphosate in soil. The amount of glyphosate and phosphate adsorbed by the various kinds of adsorbents was found to decrease in the order: oxides > silicates > soils. For the soils tested aluminium oxides, and to a lesser extent iron oxides seem the most important components in determining a soil's ability to adsorb phosphate and glyphosate, whereas the clay content and clay type seem of minor or little importance for adsorption of these species.

Distribution of Imported Glyphosate in Quackgrass (Elytrigia repens) Rhizomes in Relation to Assimilate Accumulation

The fact that quackgrass may occasionally escape control by the herbicide glyphosate is thought to result from the wide range in growth rate and sink activity among rhizome buds, especially in older portions of the rhizome. To study growth of rhizome structures, we supplied whole plants with14CO2throughout a 10-h light period and determined the amount of labeled carbon accumulated by the end of the subsequent 14-h night. Growth of rhizome structures during this 24-h period was estimated by determining their growth rate coefficients: the amount of labeled carbon accumulated per unit of carbon present in the structure. Growth rate coefficients generally were high for the rhizome tip that is enclosed in a sheath and the adjacent bud and rhizome segment, with values decreasing rapidly in a basipetal direction. However, extensive differences in the level and pattern of assimilate accumulation among rhizome structures were observed as rhizome development continued. Glyphosate accumulation generally paralleled the level of assimilate accumulation even though the range among rhizome structures for both increased with rhizome age. As a result of the increased variability among buds, some of the older buds will accumulate only a small, perhaps sublethal, amount of glyphosate and this may explain the tendency of the buds in older regions to escape control by glyphosate.