<p>PPO inhibitors are a valuable group of herbicides that provide soil-residual and foliar control of glyphosate resistant <em>Amaranthus</em> species. The ΔG210 mutation in the <em>PPX2</em> gene confers PPO-inhibitor resistance and has been present in the Midwest for more than a decade. Until recently, PPO-inhibitor resistance in waterhemp was attributable to just the ΔG210 mutation in the <em>PPX2</em> gene, but recently, several new PPO-resistant biotypes have been discovered in waterhemp and Palmer amaranth. A possible explanation is a change in PPO-inhibitor use patterns and commonly used active ingredients.</p> <p>A direct comparison of the ΔG210 mutation and a new mutation, R128G, was conducted in the greenhouse. Results indicate that the R128G mutation in waterhemp is not substantially better than the ΔG210 mutation with respect to conferring resistance to PPO inhibitors applied preemergence. Furthermore, there is no evidence that the utility of PPO inhibitors applied preemergence will diminish any further as a result of the R128G mutation increasing in frequency. A set of field trials was conducted to investigate how a new PPO inhibitor, trifludimoxazin, will select for resistant biotypes in the field. Overall, a greater number of resistant plants survived the foliar herbicide applications than emerged through soil applications. Trifludimoxazin did not increase the frequency of PPO-resistant individuals when applied to soil, but when applied to foliage, increased the frequency of PPO-resistant individuals by 2.5 to 2.6-fold, similar to other PPO inhibitors applied to foliage. In other experiments, investigations of waterhemp populations with unique resistance phenotypes were conducted. In populations that were more resistant than others, yet had the same ΔG210 mutation, there was no evidence of herbicide metabolism contributing to the greater resistance phenotype. In resistant populations that had no target site mutations, target site expression experiments and lipid peroxidation experiments were inconclusive. However, there was some evidence of increased target-site expression or increased antioxidant capacity as being causal mechanisms, although no mechanisms have been fully ruled out.</p>

<p>Soil residual herbicides are a vital component of the best management practices (BMPs), to provide early-season weed control in most cropping systems. The availability of a biologically effective dose of a soil residual herbicide in the soil solution is dependent on several soil parameters including soil texture, organic matter (OM), and pH.  Soil residual herbicides are currently applied as a uniform application rate over an individual field; yet soil properties can vary spatially within agricultural fields. Therefore, areas of the field are being over- and under-applied when using a uniform application rate. By integrating variable-rate (VR) technology with soil residual herbicides, the correct rate could be applied based on the intra-field soil variability. However, the extent of spatial soil variability within a field and the impact on herbicide application rates has not been well-characterized to inform whether soil residual herbicide applications should move towards variable rate applications. Therefore, the objectives of this research were to 1) determine the extent of intra-field variability of soil texture and organic matter in ten commercial Indiana fields, 2) quantify the reliability of five different combinations of spatial soil data sources, 3) determine the impact of soil sample intensity on map development and the classification accuracy for VR applications of soil residual herbicides, 4) quantify the impact of VR herbicide application on the total amount and spatial accuracy of herbicide applied according to product labels, and 5) determine if the intensive spatial characterization of soil properties is related to weed seedbank abundance and species richness to improve predictive weed management using soil residual herbicides.</p> <p><br></p> <p>Commercial soil data was generated by intensively collecting 60 soil samples in a stratified random sampling pattern in 10 agricultural fields across Indiana. Analysis of this data from commercial fields confirmed inherent field variability that would benefit from multiple management zones according to the labeled rate structures of pendimethalin, s-metolachlor, and metribuzin. Therefore, further research was conducted to determine an accurate and reliable method to delineate the fields into management zones for variable-rate residual herbicide applications based on the spatial soil variability and herbicide labels. </p> <p><br></p> <p>A modified Monte Carlo cross-validation method was used to determine the best source of spatial soil data and sampling intensity for delineating management zones for variable-rate applications of pendimethalin, s- metolachlor, and metribuzin. These sources of spatial soil data included: Soil Survey Geographic database (SSURGO) data, intensive soil samples, electrical resistivity sensors, and implement mounted optical reflectance sensors using VNIR reflectance spectroscopy. The mean management zone classification accuracy for maps developed from soil samples with and without electrical conductivity was similar for 75% of all maps developed across each field, herbicide, and sampling intensity. The method of using soil sampling data combined with electrical conductivity (SSEC) maps was most frequently the top performing source of spatial soil data. The most reliable sampling intensity was one sample per hectare which resulted in lower root mean squared error (RMSE) OM values, higher management zone classification accuracy, and more reliable predictions for the number of management zones within each field. </p> <p><br></p> <p>Using VR maps developed from SSEC with one sample per hectare sampling intensity, additional research was conducted to compare the amount of herbicide and field area that was over-or under-applied with a uniform application rate compared to a VR application for 10 corn and soybean residual herbicides. Although research from our previous study documented that spatial soil variability was extensive enough to require two or more management zones for all fields, the same labeled herbicide dose defined for multiple soil conditions led to 20% of all maps not requiring a variable rate application (VRA). Additionally, no difference was shown in the total amount applied of herbicide in an individual field between a variable and uniform application rate for all herbicides. Nonetheless, nearly half of all VR maps had 10% or more of the field area misapplied with a uniform application rate and justifies further research to determine if the proper placement of residual herbicide adds value through increased weed control in the field areas being under-applied. </p> <p><br></p> <p>Similar to soil residual herbicides, weed seedbank abundance and species richness were impacted by the variable soil conditions present within the field area. The seedbanks favor the establishment in areas of the field that promote vigorous germination, growth, and reproduction next to the competing crop. Therefore, soil sampling and weed seedbank greenhouse grow-outs were conducted in four fields to gain a better understanding in the relationship between the spatial soil and weed seedbank variability. All weed seedbank characteristics were shown to be spatially aggregated. Even though no individual or combination of soil parameters consistently explained the variability of weed seedbank abundance, species richness, or individual weed species across all four fields. However, clay content was the most persistent soil parameter to negatively impact (lower seedbank values) the soil weed seedbank.</p> <p><br></p> <p>Further field studies should be conducted across multiple sites to determine if variable-rate residual herbicide applications aid farmers by reducing the risk of crop injury in over-applied field areas and increased weed control in the areas being under-applied.  These studies should also access whether earlier emergence and/or greater weed densities occur in field areas receiving sublethal herbicide doses compared to areas receiving the optimal application rate. Additional research should investigate the utility of VR residual herbicide applications when tank-mixing multiple products during an application. Particularly, when the soil parameters used for selecting the herbicide rate are not defined the same across herbicide labels </p>

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Bactérias redutoras de sulfato (BRS) são os principais micro-organismos envolvidos na corrosão microbiologicamente induzida (CMI). Estas bactérias reduzem o sulfato, tendo como resultado a produção de H2S, o que pode influenciar os processos anódico e catódico na corrosão de materiais metálicos em ambientes marinhos, óleos e solos úmidos. Uma das formas de prevenir e controlar esse tipo de corrosão é a adição de biocidas ao meio corrosivo. Esta dissertação tem como objetivo avaliar o uso de biocidas no controle da CMI do aço AISI 1020 por BRS. Para isto, o comportamento da CMI no aço foi avaliado em água do mar sintética, em condições de anaerobiose, na ausência e na presença de uma cultura mista contendo BRS. Um biocida natural (óleo de alho) e outro comercial (glutaraldeído) foram utilizados para controlar a corrosão causada por estas bactérias. Duas formas de adição de biocida foram avaliadas: antes da formação do biofilme e após sua formação na superfície do metal. O crescimento microbiano na superfície do aço foi avaliado através da quantificação das BRS sésseis, pelo método do número mais provável (NMP). O comportamento eletroquímico do aço, na ausência e na presença de BRS e também para os ensaios com biocidas, foi estudado através das técnicas de espectroscopia de impedância eletroquímica (EIE) e polarização potenciodinâmica, sempre usando água do mar sintética como meio eletrolítico. A formação de biofilme e de produtos de corrosão na superfície do aço foi observada através da microscopia eletrônica de varredura (MEV). Os resultados mostraram que o aço exposto ao meio contendo BRS apresentou um processo corrosivo mais acelerado, quando comparado aos sistemas na ausência de micro-organismo. Esse processo foi evidenciado por um decréscimo na magnitude do arco capacitivo, nos ensaios de EIE, e um aumento da densidade de corrente de corrosão (Icorr), nos ensaios de polarização. Na análise de MEV, foi possível observar a formação de corrosão localizada após a remoção do biofilme da superfície. Os ensaios com biocidas, adicionados antes da formação de biofilmes, mostraram uma redução no número de bactérias sésseis, quando comparados com os ensaios sem biocida realizados pelo mesmo período de tempo (7 dias). Foi verificado também um decréscimo do processo corrosivo do aço, evidenciado através de aumento nos arcos capacitivos, nos ensaios de EIE e pelos menores valores de Icorr nos ensaios de polarização, quando comparados com o biofilme formado sem biocidas, nas mesmas condições. Apesar de não ter inibido completamente o crescimento das BRS sésseis, o óleo de alho apresentou maior redução no processo corrosivo quando comparado ao glutaraldeído, indicando sua possível aplicação como biocida natural nestas condições. Os ensaios realizados com biocidas adicionados após a formação do biofilme mostraram que o glutaraldeído apresentou alta eficácia em reduzir o número de células sésseis. Já o óleo de alho exibiu uma ação menos efetiva, sugerindo que este composto não conseguiu penetrar completamente a matriz do biofilme. Entretanto, ambos causaram aceleração do processo corrosivo do aço no meio estudado após 7 dias de exposição / Sulfate-reducing bacteria (SRB) are the most important microorganisms involved in the microbiologically-influenced corrosion (MIC). These bacteria reduce sulfate, resulting in the production of H2S, which may influence the anodic and cathodic processes in the corrosion of metallic materials in marine environments, oil and wet soils. One way to prevent and control this type of corrosion is the addition of biocides to the corrosive environment. This work aims to evaluate the use of biocides to control MIC of AISI 1020 steel by SRB. For this, the behavior of MIC in carbon steel was evaluated in artificial seawater, under anaerobic conditions, in the absence and in the presence of a mixed culture containing SRB. A natural biocide (garlic oil) and a commercial one (glutaraldehyde) were used to control the corrosion caused by these bacteria. Two ways of biocide addition were evaluated: before the formation of biofilm and after its formation on the metal surface. Microbial growth on the steel surface was evaluated by quantifying the sessile SRB, by using the most probable number method (MPN).The electrochemical behavior of the steel in the absence and presence of SRB, as well as in the experiments containing the biocides, was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, always using artificial seawater as the electrolytic medium. The biofilm formation and the corrosion products on the steel surface were observed by scanning electron microscopy (SEM).The results showed that the steel exposed to medium containing SRB exhibited an accelerated corrosion process when compared to systems without the microorganisms. This process was evidenced by a decrease in the magnitude of the capacitive loop, in EIS experiments, and an increase of the corrosion current density (Icorr), in polarization tests. By SEM analysis, it was possible to observe the formation of localized corrosion after the biofilm removal. The experiments with biocides, added before the formation of biofilms, showed a reduction in the number of sessile bacteria, compared with the tests without biocide performed on the same time period (7 days). It was also found a decrease in steel corrosive process, evidenced by an increase in the capacitive loops in the EIS tests, and by the smaller Icorr values in polarization tests, when compared to the biofilm formatted without biocides under the same conditions. Although it has not completely inhibited the growth of BRS sessile, garlic oil showed a greater reduction in corrosion process when compared to glutaraldehyde, indicating its possible application as a natural biocide under these conditions. The experiments performed with biocides added after the biofilm formation showed that glutaraldehyde exhibited high efficacy in reducing the number of sessile cells. On the contrary, the garlic oil exhibited a less effective action, suggesting that this compound could not completely penetrate the biofilm matrix. However, both biocides accelerated the steel corrosion process in the studied medium after 7 days of exposure

Introduction. This paper discusses the most topical issues of the Biocidal Products Directive (BPD) implementation, in particular, the impact on the social and health safety on various population groups, environmental safety, trade, manufacturing and their prospectives. The Aim of the Study – to evaluate the development of the biocides market and its participants in Lithuania. The Tasks – to evaluate the impact of the approximation of the laws of Lithuania and the European Union, concerning the placing of biocides on the market and its participants. Methods. Based on the "Methodology for impact of the regulatory laws assessment", the study identifies changes in the biocides market and the activity of its participants. A sample survey of manufacturers of biocides and of the users (personal health care institutions and preventive disinfection and disinfestation enterprises) was conducted. The analysis and evaluation of the available biocides database was also undertaken and SPSS statistics software was used to measure the statistical significance of the results. The market was assessed by the application of the criteria laid down in the BPD, in particular, the number of authorized biocides, distribution of product types, distribution of biocides according to categories of users, distribution of use of identified and notified active substances of biocides. Results. The study demonstrated that the Lithuanian biocides market has changed following the implementation of the BPD:... [to full text]

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Bactérias redutoras de sulfato (BRS) são os principais micro-organismos envolvidos na corrosão microbiologicamente induzida (CMI). Estas bactérias reduzem o sulfato, tendo como resultado a produção de H2S, o que pode influenciar os processos anódico e catódico na corrosão de materiais metálicos em ambientes marinhos, óleos e solos úmidos. Uma das formas de prevenir e controlar esse tipo de corrosão é a adição de biocidas ao meio corrosivo. Esta dissertação tem como objetivo avaliar o uso de biocidas no controle da CMI do aço AISI 1020 por BRS. Para isto, o comportamento da CMI no aço foi avaliado em água do mar sintética, em condições de anaerobiose, na ausência e na presença de uma cultura mista contendo BRS. Um biocida natural (óleo de alho) e outro comercial (glutaraldeído) foram utilizados para controlar a corrosão causada por estas bactérias. Duas formas de adição de biocida foram avaliadas: antes da formação do biofilme e após sua formação na superfície do metal. O crescimento microbiano na superfície do aço foi avaliado através da quantificação das BRS sésseis, pelo método do número mais provável (NMP). O comportamento eletroquímico do aço, na ausência e na presença de BRS e também para os ensaios com biocidas, foi estudado através das técnicas de espectroscopia de impedância eletroquímica (EIE) e polarização potenciodinâmica, sempre usando água do mar sintética como meio eletrolítico. A formação de biofilme e de produtos de corrosão na superfície do aço foi observada através da microscopia eletrônica de varredura (MEV). Os resultados mostraram que o aço exposto ao meio contendo BRS apresentou um processo corrosivo mais acelerado, quando comparado aos sistemas na ausência de micro-organismo. Esse processo foi evidenciado por um decréscimo na magnitude do arco capacitivo, nos ensaios de EIE, e um aumento da densidade de corrente de corrosão (Icorr), nos ensaios de polarização. Na análise de MEV, foi possível observar a formação de corrosão localizada após a remoção do biofilme da superfície. Os ensaios com biocidas, adicionados antes da formação de biofilmes, mostraram uma redução no número de bactérias sésseis, quando comparados com os ensaios sem biocida realizados pelo mesmo período de tempo (7 dias). Foi verificado também um decréscimo do processo corrosivo do aço, evidenciado através de aumento nos arcos capacitivos, nos ensaios de EIE e pelos menores valores de Icorr nos ensaios de polarização, quando comparados com o biofilme formado sem biocidas, nas mesmas condições. Apesar de não ter inibido completamente o crescimento das BRS sésseis, o óleo de alho apresentou maior redução no processo corrosivo quando comparado ao glutaraldeído, indicando sua possível aplicação como biocida natural nestas condições. Os ensaios realizados com biocidas adicionados após a formação do biofilme mostraram que o glutaraldeído apresentou alta eficácia em reduzir o número de células sésseis. Já o óleo de alho exibiu uma ação menos efetiva, sugerindo que este composto não conseguiu penetrar completamente a matriz do biofilme. Entretanto, ambos causaram aceleração do processo corrosivo do aço no meio estudado após 7 dias de exposição / Sulfate-reducing bacteria (SRB) are the most important microorganisms involved in the microbiologically-influenced corrosion (MIC). These bacteria reduce sulfate, resulting in the production of H2S, which may influence the anodic and cathodic processes in the corrosion of metallic materials in marine environments, oil and wet soils. One way to prevent and control this type of corrosion is the addition of biocides to the corrosive environment. This work aims to evaluate the use of biocides to control MIC of AISI 1020 steel by SRB. For this, the behavior of MIC in carbon steel was evaluated in artificial seawater, under anaerobic conditions, in the absence and in the presence of a mixed culture containing SRB. A natural biocide (garlic oil) and a commercial one (glutaraldehyde) were used to control the corrosion caused by these bacteria. Two ways of biocide addition were evaluated: before the formation of biofilm and after its formation on the metal surface. Microbial growth on the steel surface was evaluated by quantifying the sessile SRB, by using the most probable number method (MPN).The electrochemical behavior of the steel in the absence and presence of SRB, as well as in the experiments containing the biocides, was studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, always using artificial seawater as the electrolytic medium. The biofilm formation and the corrosion products on the steel surface were observed by scanning electron microscopy (SEM).The results showed that the steel exposed to medium containing SRB exhibited an accelerated corrosion process when compared to systems without the microorganisms. This process was evidenced by a decrease in the magnitude of the capacitive loop, in EIS experiments, and an increase of the corrosion current density (Icorr), in polarization tests. By SEM analysis, it was possible to observe the formation of localized corrosion after the biofilm removal. The experiments with biocides, added before the formation of biofilms, showed a reduction in the number of sessile bacteria, compared with the tests without biocide performed on the same time period (7 days). It was also found a decrease in steel corrosive process, evidenced by an increase in the capacitive loops in the EIS tests, and by the smaller Icorr values in polarization tests, when compared to the biofilm formatted without biocides under the same conditions. Although it has not completely inhibited the growth of BRS sessile, garlic oil showed a greater reduction in corrosion process when compared to glutaraldehyde, indicating its possible application as a natural biocide under these conditions. The experiments performed with biocides added after the biofilm formation showed that glutaraldehyde exhibited high efficacy in reducing the number of sessile cells. On the contrary, the garlic oil exhibited a less effective action, suggesting that this compound could not completely penetrate the biofilm matrix. However, both biocides accelerated the steel corrosion process in the studied medium after 7 days of exposure

A local integrated pulp and paper Kraft mill had come under pressure from the local communities and mill personnel to reduce the odours that were perceived to be generated at the Farm Dams and irrigation farm situated adjacent to the mill. The typical odours associated with Kraft mills are due to the generation of four reduced sulphur compounds such as hydrogen sulphide (H2S), methyl-mercaptan (CH3SH), dimethyl-sulphide (CH3)2S and dimethyl-disulphide (CH3)2S2. These compounds are collectively referred to as Total Reduced Sulphur (TRS) components which are generated as a direct result of the Kraft pulping and chemical recovery process. These components can either be in the gaseous or aqueous phase depending on the characteristics of the effluent. Gaseous and aqueous TRS profiling of the mill indicated that hydrogen sulphide (H2S) was the main odour component generated and emitted from the Clarifiers and the Treated Effluent Transfer Sump (TETS) at the effluent treatment plant. The hydrogen sulphide (H2S) emission levels were affected by process upsets, sludge removal frequencies, chemical composition of the effluent, Sulphate Reducing Bacteria (SRB) activity, pH and temperature fluctuations. Treatment options such as pH control using slaked lime, dosing of biocides, addition of biomodifiers and/or a sulphate reduction inhibitor were investigated. The use of slaked lime, Ca(OH) 2, for pH control was not practical due to continuous pH fluctuations, increasing the pH would increase the scaling tendencies of the effluent and would also affect the soil cation-anion exchange properties of the irrigated farm land. The use of non-oxidising biocides was effective in reducing SRB activity between 99.2% and 99.8% at dosages between 4 mg/l and 25 mg/l. However, the use of biocides was not considered as a long term treatment option due to the various disadvantages such as the stability of the biocides at fluctuating pH and temperatures, half-life, environmental accumulation, toxicity and costs. The aqueous H2S level was reduced by 79% using different combinations of biomodifiers (nitrates, nitrites, molybdenum). Increasing the dosages of the biomodifiers (> 500mg/l) would be required to increase the reduction of H2S levels by more than 79%. The increased dosages would significantly increase the cost of the treatment programme. The accumulation of nitrates, nitrites and molybdenum could affect the soil texture, cation-anion exchange capacity, permeability, Sodium Absorption Ratio (SAR) and nutrient availability. A more environmentally friendly and cost effective treatment was found using sodium nitrate (biomodifier) together with AQ (sulphate reduction inhibitor). The continuous dosing of 50 mg/l sodium nitrate together with 4 mg/l AQ would be effective in reducing the average aqueous H2S levels (40 mg/l) by at least 92%. This treatment would also be compatible with aeration or oxidation procedures to further increase the removal of H2S to achieve an aqueous H2S level of <1 mg/l. Aeration or oxidation would also increase the dissolved oxygen and COD levels, increase the inhibition of SRB activity and oxidise any reduced sulphur. The dosing of sodium nitrate and AQ to control the generation of H2S is not patented in South Africa. It can, therefore, be used to treat the Kraft mill effluent without violating any intellectual property rights in South Africa. / Dissertation (MSc(Applied Science))--University of Pretoria, 2008. / Chemical Engineering / unrestricted

The thesis is focused on theoretical principles of demarcation of products with health effects in the EU law and on the reflection of these issues in the application and administrative practice in commercial law. The thesis developed yet been brought judicial interpretation with the scientific interpretation of certain key and decisive problems that separate from each other law-regimes of regulation: medicinal product for human use, foods, cosmetics products, medical devices and biocides. Correct law-regime for a particular product is determinating of the general legal basis in the EU internal market. It is therefore a important problem not only in EU law, but also in EU economic. Thesis results are highly critical of current practice in the local markets of EU member states, especially Czech Republic, and in many instances documented sub-optimal application of this law in general practice.