Indaziflam: Control Effectiveness in Monocotyledonous and Eudicotyledonous Weeds as a Function of Herbicide Dose and Soil Texture.

<b>Background and Objective:</b> The indaziflam herbicide has efficiency in the control of monocotyledons weeds and is recommended for some eudicotyledonous species. However, the efficiency of the control can vary to the detriment of the species, dose and soil texture. Therefore, the objective of the present work was to evaluate the effectiveness of the control of indaziflam herbicide for weeds species <i>Mucuna aterrima</i>, <i>Sorghum halepense</i>, <i>Ipomoea purpurea</i>, <i>Rottboellia exaltata</i>, <i>Urochloa decumbens</i>, <i>Merremia aegyptia</i>, <i>Cenchrus echinatus</i>, <i>Digitaria horizontalis</i>, <i>Panicum maximum</i>, <i>Tridax procumbens</i>, <i>Urochloa plantaginea</i> and <i>Eleusine indica</i>, besides elaborating the calculation of DL₈₀, DL₉₀ and DL₉₅ of the product in two types of soil. Material and Methods: Thus, experiments were carried out in a greenhouse, isolated for each weed species, in a completely randomized experimental design, with four replications and a 10×2 factorial scheme, with ten doses of the herbicide indaziflam (0 D, 1/16 D, 1/8 D, 1/4 D, 1/2 D, D, 2 D, 4 D, 8 D, 16 D, being D = 100 g ha¹), applied in pre-emergence and two contrasting soil textures (clayey and sandy). At 7, 14, 21, 28, 35, 42, 49 and 56 days after weed emergence (DAE), visual control assessments were performed and in the last evaluation, the dry mass of the aerial part was performed. <b>Results:</b> The weeds of the Poaceae family showed greater susceptibility to the indaziflam herbicide, on the other hand, the <i>Mucuna aterrima</i>, <i>Ipomoea purpurea</i> and <i>Merremia aegyptia </i>weeds required a higher dose of active ingredient to be controlled efficiently. <b>Conclusion:</b> In general, the current study concluded that a lesser amount of active ingredient was needed in sandy soil than in clayey soils to promote adequate weed control. Therefore, the difference in the susceptibility of the studied plants as function of dose indaziflam, weeds species and soil texture.

Impact of feed glyphosate residues on broiler breeder egg production and egg hatchability.

Glyphosate is the active substance in glyphosate-based herbicides, e.g. Roundup. Its widespread application on feed crops leaves residues in the feed. Glyphosate has antimicrobial and mineral chelating properties and we investigated whether there is an association between feed residues of glyphosate on the one side and broiler breeder egg laying percent and egg hatchability on the other side. Twenty-six feed samples from five conventional flocks producing hatching eggs were analysed for glyphosate. Data on laying percent and egg hatchability from periods following each feed sampling were then associated with feed residues of glyphosate. The average glyphosate residue level was 0.09 mg/kg, maximum was 0.19 and minimum was 0.004 mg/kg. Average laying percent over observation days was 65% (SD = 5.4%) and average hatchability was 79% (SD = 5.8%). We found a negative association between feed glyphosate residue level and hatchability (P = 0.03) when adjusted for breeder age, storage time of eggs on farm before delivery and storage time at hatchery before incubation start. No association was found with laying percent (P = 0.59) adjusted for breeder age. The range of glyphosate concentrations in feed was narrow and should be kept in mind when interpreting both significant and non-significant associations with glyphosate residue concentrations. In nine of 24 analysed conventional eggs the concentration of glyphosate in yolk was above the detection limit however below the quantification limit indicating that traces of glyphosate are common in conventional eggs.

Synthetic approaches to the 2015-2018 new agrochemicals.

In this review, the synthesis of 33 agrochemicals that received an international standardization organization (ISO) name between January 2015 and December 2018 is described. The aim is to showcase the broad range and scope of reactions, reagents and intermediates used to discover and produce the latest active ingredients addressing the crop protection industry's needs.

Why Regulators Lost Track and Control of Pesticide Risks: Lessons From the Case of Glyphosate-Based Herbicides and Genetically Engineered-Crop Technology.

PURPOSE OF REVIEW: The approval of genetically engineered (GE) crops in the late 1990s triggered dramatic changes in corn, soybean, and cotton pest management systems, as well as complex, novel regulatory challenges. Lessons learned are reviewed and solutions described. RECENT FINDINGS: Government-imposed resistance management provisions can work and adapt to changing circumstances, but within the private sector, pressures to gain and hold market share have thus far trumped the widely recognized need for resistance management. Risks arising from the use of formulated pesticides often exceed by a wide margin those in regulatory risk assessments based on data derived from studies on nearly 100% pure active ingredients. Innovative policy changes are needed in four problem areas: excessive faith in the accuracy of pre-market risk assessments and regulatory thresholds; post-approval monitoring of actual impacts; risk arising from formulated pesticides, rather than just pure active ingredient; challenges inherent in assessing and mitigating the combined impacts of all GE traits and associated pesticides on agroecosystems, as opposed to each trait or pesticide alone; and, tools to deal with failing pest management systems.

Ecotoxicity thresholds for ametryn, diuron, hexazinone and simazine in fresh and marine waters.

Triazine and urea herbicides are two groups of photosystem II inhibiting herbicides frequently detected in surface, ground and marine waters. Yet, there are few water quality guidelines for herbicides. Ecotoxicity thresholds (ETs) for ametryn, hexazinone and simazine (triazine herbicides) and diuron (a urea herbicide) were calculated using the Australian and New Zealand method for deriving guideline values to protect fresh and marine ecosystems. Four ETs were derived for each chemical and ecosystem that should theoretically protect 99, 95, 90 and 80% of species (i.e. PC99, PC95, PC90 and PC80, respectively). For all four herbicides, the phototrophic species were significantly more sensitive than non-phototrophic species, and therefore, only the former data were used to calculate the ETs. Comparison of the ET values to measured concentrations in 2606 samples from 15 waterways that discharge to the Great Barrier Reef (2011-2015) found three exceedances of the simazine PC99, regular exceedances (up to 30%) of the PC99 in a limited number of rivers for ametryn and hexazinone and frequent (> 40%) exceedances of the PC99 and PC95 ETs in at least four waterways for diuron. There were no exceedances of the marine ETs in inshore reef areas. Further, ecotoxicity data are required for ametryn and hexazinone to fresh and marine phototrophic species, for simazine to marine phototrophic species, for tropical phototrophic species, repeated pulse exposures and long-term (2 to 12 months) exposures to environmentally relevant concentrations.

Synthetic approaches to the 2010-2014 new agrochemicals.

In this review, the synthesis of 30 agrochemicals that received an international standardization organization (ISO) name during the last five years (January 2010 to December 2014) is described. The aim is to showcase the range and scope of chemistries used to discover or produce the latest active ingredients addressing the crop protection industry's needs.

Potential toxic effects of glyphosate and its commercial formulations below regulatory limits.

Glyphosate-based herbicides (GlyBH), including Roundup, are the most widely used pesticides worldwide. Their uses have increased exponentially since their introduction on the market. Residue levels in food or water, as well as human exposures, are escalating. We have reviewed the toxic effects of GlyBH measured below regulatory limits by evaluating the published literature and regulatory reports. We reveal a coherent body of evidence indicating that GlyBH could be toxic below the regulatory lowest observed adverse effect level for chronic toxic effects. It includes teratogenic, tumorigenic and hepatorenal effects. They could be explained by endocrine disruption and oxidative stress, causing metabolic alterations, depending on dose and exposure time. Some effects were detected in the range of the recommended acceptable daily intake. Toxic effects of commercial formulations can also be explained by GlyBH adjuvants, which have their own toxicity, but also enhance glyphosate toxicity. These challenge the assumption of safety of GlyBH at the levels at which they contaminate food and the environment, albeit these levels may fall below regulatory thresholds. Neurodevelopmental, reproductive, and transgenerational effects of GlyBH must be revisited, since a growing body of knowledge suggests the predominance of endocrine disrupting mechanisms caused by environmentally relevant levels of exposure.

Resistance risk assessment within herbicide authorisation--a call for sensitivity data.

In most European countries, the risk of herbicide resistance is assessed as part of the authorisation of herbicides in accordance with EPPO Standard PP 1/213(2). Because the susceptibility of weed populations to a certain herbicide may vary greatly, one part of resistance risk assessment is the testing for sensitivity variation among different populations of target weed species with a high resistance risk. This paper emphasises the importance of sensitivity data provision with regard to the recent EU Regulation (EC) 1107/2009 concerning the placing of plant protection products on the market and outlines the main technical requirements for sensitivity data. A useful principle is that sensitivity data should be provided for all herbicides with a high resistance risk regardless of whether resistance has already evolved against the herbicidal substance. Methodical details regarding the generation of sensitivity data are discussed, together with remaining questions that will need to be addressed if a harmonised assessment of herbicide resistance risk is to be achieved.

Quantitative analysis of triazine herbicides in environmental samples by using high performance liquid chromatography and diode array detection combined with second-order calibration based on an alternating penalty trilinear decomposition algorithm.

A novel application of second-order calibration method based on an alternating penalty trilinear decomposition (APTLD) algorithm is presented to treat the data from high performance liquid chromatography-diode array detection (HPLC-DAD). The method makes it possible to accurately and reliably analyze atrazine (ATR), ametryn (AME) and prometryne (PRO) contents in soil, river sediment and wastewater samples. Satisfactory results are obtained although the elution and spectral profiles of the analytes are heavily overlapped with the background in environmental samples. The obtained average recoveries for ATR, AME and PRO are 99.7±1.5, 98.4±4.7 and 97.0±4.4% in soil samples, 100.1±3.2, 100.7±3.4 and 96.4±3.8% in river sediment samples, and 100.1±3.5, 101.8±4.2 and 101.4±3.6% in wastewater samples, respectively. Furthermore, the accuracy and precision of the proposed method are evaluated with the elliptical joint confidence region (EJCR) test. It lights a new avenue to determine quantitatively herbicides in environmental samples with a simple pretreatment procedure and provides the scientific basis for an improved environment management through a better understanding of the wastewater-soil-river sediment system as a whole.

Does the actual standard of 0.1 microg/L overestimate or underestimate the risk of plant protection products to groundwater ecosystems?

The present groundwater standard of 0.1 microg/L for plant protection products (PPPs) has been under much debate because an ecotoxicological base is missing. In the present study, groundwater threshold values were calculated for all PPPs currently included in Annex I to Directive 91/414/EEC using three different approaches: (1) first-tier (Daphnia magna and Vibrio fisheri); (2) species sensitivity distributions, constructed for surrogate freshwater organisms for the truncated groundwater biodiversity; (3) the case-based model PERPEST. For the majority of the PPPs, the trigger value of 0.1 microg/L appears to be sufficiently protective. However, it may not fully protect groundwater life from several insecticides. Implications for the environmental risk assessment of groundwater and recommendations for future research are discussed.

Determination of water quality standards for chemical mixtures: extension of a methodology developed for herbicides to a group of insecticides and a group of pharmaceuticals.

Monitoring surveys throughout America and Europe have demonstrated the widespread presence of organic synthetic substances such as pesticides and pharmaceuticals in surface water. To avoid deleterious effects on the aquatic system, many countries determine water quality criteria for pesticides. For each substance, the comparison of the concentration measured in water with its criterion gives an indication of the pressure this substance put on the aquatic system. However, in the environment, aquatic organisms are not only exposed to single pesticides but typically to mixtures of these substances. It is therefore of particular importance to take mixtures into account when defining water quality criteria, which is rarely done yet. We recently developed a method to define consistent and comparable water quality criteria for mixtures of herbicides having a similar mode of action. These criteria are calculated based on species sensitivity curves; the method assumes that these curves are parallel for substances having similar mode of action. The aim of this study was to apply our method to six organophosphates (insecticides) and to three ß-blockers (pharmaceuticals), other groups of compounds commonly detected in surface water. We found some evidence that the developed methodology gives consistent results for these groups too. The hypothesis of parallelism was accepted in 2/3 (ß-blockers) and 2/6 of the cases (organophosphates) for both species sensitivity curves based on effect concentrations 50% and on no-observed effect concentrations. The use of water quality criteria for mixture is illustrated by two case studies, which show the importance of taking mixtures into account in water quality legislation.

The economics of atrazine.

It is often claimed that atrazine is of great economic benefit to corn growers, but support for this claim is limited. Some cost-benefit studies have assumed that atrazine boosts corn yields by 6%; an extensive review found a 3%-4% average yield increase; other research suggests only a 1% yield effect. Syngenta, the producer of atrazine, also makes mesotrione, an alternative herbicide that does about the same amount for corn yields as atrazine. Italy and Germany both banned atrazine in 1991, with no decrease in corn yields or harvested area. Even if atrazine leads to 6% more corn production, it is not certain that this would justify its continued use; a 1%, or perhaps zero, change does not warrant large-scale exposure of humans and the environment to this potentially hazardous chemical.

Modifying sorbents in controlled release formulations to prevent herbicides pollution.

The herbicides chloridazon and metribuzin, identified as groundwater pollutants, were incorporated in alginate-based granules to obtain controlled release properties. In this research the effect of incorporation of sorbents such as bentonite, anthracite and activated carbon in alginate basic formulation were not only studied on encapsulation efficiency but also on the release rate of herbicides which was studied using water release kinetic tests. In addition, sorption studies of herbicides with bentonite, anthracite and activated carbon were made. The kinetic experiments of chloridazon and metribuzin release in water have shown that the release rate is higher in metribuzin systems than in those prepared with chloridazon, which has lower water solubility. Besides, it can be deduced that the use of sorbents reduces the release rate of the chloridazon and metribuzin in comparison to the technical product and to the alginate formulation without sorbents. The highest decrease in release rate corresponds to the formulations prepared with activated carbon as a sorbent. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, T(50), were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the herbicide release data, the release of chloridazon and metribuzin from the various formulations into water is controlled by a diffusion mechanism. Sorption capacity of the sorbents for chloridazon and metribuzin, ranging from 0.53mgkg(-1) for the metribuzin sorption on bentonite to 2.03x10(5)mgkg(-1) for the sorption of chloridazon on the activated carbon, was the most important factor modulating the herbicide release.

New approach to large-volume injection in reversed-phase high performance liquid chromatography: determination of atrazine and hydroxyatrazine in soil samples.

A well established method of direct injection of larger than conventional sample volumes ranging from 0.1 mL to 10 mL in HPLC is the injection valve method in which a loop of tubing is totally or partially filled with sample. Recent HPLC pumps have a flow-rate setting accuracy of +/- 1-2% over a flow-rate range from 0.1 mL/min to 10 mL/min and the flow stability is 0.2% or less. Quarternary low pressure gradient pumps are widely available and used, but all their hydraulic lines are seldom utilised. The idea of using one line of a common commercial HPLC quaternary low-pressure pump for direct on-column injection (pumping) of large sample volumes ranging from 1 mL to 100 mL was tested. This approach was evaluated during practical work on the development of an RP-HPLC method of determination of residual atrazine and hydroxyatrazine. In lysimetric environmental experiments hydroxyatrazine was formed in situ in a soil column by hydrolysis of atrazine. The results proved the applicability of this approach not only in experiments with model mixtures of analytes at microg/L levels in solutions. Analysis of 20 mL of soil leachates and extracts of soil samples containing atrazine and hydroxyatrazine at the 10 microg/kg level (in dry soil) revealed that good figures-of-merit were preserved, even in the presence of a large excess of humic substances.

European Union bans atrazine, while the United States negotiates continued use.

Atrazine is a common agricultural herbicide with endocrine disruptor activity. There is evidence that it interferes with reproduction and development, and may cause cancer. Although the U.S. Environmental Protection Agency (EPA) approved its continued use in October 2003, that same month the European Union (EU) announced a ban of atrazine because of ubiquitous and unpreventable water contamination. The authors reviewed regulatory procedures and government documents, and report efforts by the manufacturer of atrazine, Syngenta, to influence the U.S. atrazine assessment, by submitting flawed scientific data as evidence of no harm, and by meeting repeatedly and privately with EPA to negotiate the government's regulatory approach. Many of the details of these negotiations continue to be withheld from the public, despite EPA regulations and federal open-government laws that require such decisions to be made in the open.

A new on-line micellar-enhanced photochemically-induced fluorescence method for determination of phenylurea herbicide residues in water.

A new flow injection analysis micellar-enhanced photochemically induced fluorescence (FIA-MEPIF) method was developed for the determination of four phenylurea herbicides, including isoproturon, neburon, linuron and diuron. On-line photoconversion under UV irradiation of these herbicides into strongly fluorescent photoproducts was performed in buffered aqueous solutions and in the presence of surfactants [sodium dodecyl sulphate (SDS) or cetyl trimethyl ammonium chloride (CTAC)] at micellar concentrations. The MEPIF and FIA parameters were optimized. The analytical figures of merit for the determination of the four herbicides were satisfactory, with concentration linear dynamic ranges over about one to two orders of magnitude, detection limits of 0.33-0.92 mg[sol ]L and relative standard deviations of 1.3-11%, according to the compound. Application to the analysis of fortified tap water samples yielded good recovery values (91-103%, according to the herbicide). Our results show that the on-line MEPIF-FIA method is simple, versatile, sensitive and can be easily applied to quantify pollutant residues in multiresidue systems.

Toxicity of organic compounds to marine invertebrate embryos and larvae: a comparison between the sea urchin embryogenesis bioassay and alternative test species.

This study investigated the toxic effects of the insecticides lindane and chlorpyrifos, the herbicide diuron, the organometallic antifoulant tributyltin (TBT), and the surfactant sodium dodecyl sulfate (SDS) on the early life stages of Paracentrotus lividus (Echinodermata, Euechinoidea), Ciona intestinalis (Chordata, Ascidiacea), Maja squinado and Palaemon serratus (Arthropoda, Crustacea) in laboratory acute toxicity tests. The assays studied embryogenesis success from fertilized egg to normal larvae in P. lividus (48 h incubation at 20 degrees C) and C. intestinalis (24 h incubation at 20 degrees C), and larval mortality at 24 and 48 h in M. squinado and P. serratus. For P. lividus, the median effective concentrations (EC50) reducing percentages of normal larvae by 50% were: 350 microg l(-1) for chlorpyrifos, 5500 microg l(-1) for diuron, 4277 microg l(-1) for SDS, and 0.309 microg l(-1) for TBT. For C. intestinalis, the EC50 values affecting embryogenesis success were 5666 microg l(-1) for chlorpyrifos, 24,397 microg (l-1) for diuron, 4412 microg l(-1) for lindane, 5145 microg I(-1) for SDS, and 7.1 microg l(-1) for TBT. The median lethal concentrations (LC50) for M. squinado larval survival were 0.84 microg l(-1) (24 h) and 0.79 microg l(-1) (48 h) for chlorpyrifos, 2.23 microg(l(-1) (24 h) and 2.18 microg l(-1) (48 h) for lindane, and 687 microg l(-1) (48 h) for SDS. For P. serratus the LC50 values obtained were 0.35 microg l(-1) (24 h) and 0.22 microg l(-1) (48 h) for chlorpyrifos, 3011 microg l(-1) (24 h) and 3044 microg l(-1) (48 h) for diuron, 5.20 microg l(-1) (24 h) and 5.59 microg l(-1) (48 h) for lindane, and 22.30 microg l(-1) (24 h) and 17.52 microg l(-1) (48 h) for TBT. Decapod larvae, as expected, were markedly more sensitive to the insecticides than sea urchins and ascidians, and SDS was the least toxic compound tested for these organisms. Lowest observed effect concentrations (LOEC) of TBT for sea urchin and ascidian embryos, chlorpyrifos and lindane for crustacean larvae, and SDS, were similar to those found in many coastal areas indicating that there would be a risk to invertebrate embryos and larvae from exposure in the field to these pollutants.

Analytical method for the determination of metolachlor, acetochlor, alachlor, dimethenamid, and their corresponding ethanesulfonic and oxanillic acid degradates in water using SPE and LC/ESI-MS/MS.

A Good Laboratory Practices (GLP) validated, multiresidue analytical method is presented for the determination of the chloroacetanilide herbicides metolachlor, acetochlor, and alachlor, the chloroacetamide herbicide dimethenamid, and their respective ethanesulfonic (ESA) and oxanillic (OA) acid degradates in ground and surface water. A 50-mL water sample is subjected to purification using a C-18 SPE column. The four parent components and their eight ESA and OA degradates are isolated using 80/20 methanol/water (v/v) for elution. The eluate is reduced to < 1.0 mL and reconstituted in 10/90 acetonitrile/water (v/v) to the desired final fraction volume. Final analysis is accomplished using liquid chromatography/electrospray ionization-mass spectrometry/mass spectrometry in the + (parent compounds) and - (ESA and OA degradates) ion modes by monitoring appropriate precursor/product ion pairs for each of the 12 analytes. The method limit of quantification is 0.10 ppb and the limit of detection is 0.125 ng injected for each analyte. Average procedural recovery data range from 95 to 105% for fortification levels of 0.10-100 ppb. The method validation study was performed following GLP guidelines.

Electrocatalytic amperometric determination of amitrole using a cobalt-phthalocyanine-modified carbon paste electrode.

Cobalt-phthalocyanine-modified carbon paste electrodes are shown to be excellent indicators for electrocatalytic amperometric measurements of triazolic herbicides such as amitrole, at low oxidation potentials (+0.40 V). The detection and determination of amitrole in flow injection analysis with a modified carbon paste electrode with Co-phthalocyanine is described. The concentrations of amitrole in 0.1 M NaOH solutions were determined using the electrocatalytic oxidation signal corresponding to the Co(II)/Co(III) redox process. A detection limit of 0.04 microg mL(-1) (4 ng amitrole) was obtained for a sample loop of 100 microL at a fixed potential of +0.55 V (vs. Ag/AgCl) in 0.1 M NaOH and a flow rate of 4.0 mL min(-1). Furthermore, the modified carbon paste electrodes offers reproducible responses in such a system, and the relative standard deviation was 3.3% using the same surface, 5.1% using different surface, and 6.9% using different pastes. The performance of the cobalt-phthalocyanine-modified carbon paste electrodes is illustrated here for the determination of amitrole in commercial formulations. The response of the electrodes is stable, with more than 80% of the initial retained activity after 50 min of continuous use.

Efficiency of safety measures applied to a manual knapsack sprayer for paraquat application to maize (Zea mays L.).

The objectives of the present study were to evaluate the safety of mixer/loaders and applicators of paraquat to maize crop by knapsack sprayers and to determine the efficacy of safety measures applied to the sprayers. Potential dermal exposure (PDE) was evaluated in 22 worker body parts. The Cu2+ cation of a copper-based fungicide was used as tracer in the spray solution. Sanitary pads and cotton gloves were used to collect the pesticide solution on the sampled body parts. It was observed that paraquat application in front of the applicator's body (0.5 and 1.0 m lance) is unsafe because PDE was 1,979.8 ml/day (for 0.5 m lance) and 1,290.4 ml/day (for 1.0 m lance) and needs 50-80% and 37-69% control of PDE respectively. Control can be achieved by the use of protective garment on the legs and feet only, which received 92-93% of the PDE. Switching the spray nozzle to the back of the operator reduced the PDE by 98% and was sufficient to make working conditions safe, while maintaining the efficiency of application and making the work lighter and more comfortable. Mixer/loaders received 86% of the PDE to the hands and the work condition was safe (MOS > 1), however impermeable gloves could be used as a further safety measure.