Commercial Dose Research Articles

Is "Slow Inhalation" Always Suitable for Pressurized Metered Dose Inhaler?

To achieve adequate inhalation therapy, a proper inhalation technique is needed in clinical practice. However, there is limited information on proper inhalation flow patterns of commercial inhalers. Here, we quantitatively estimated airway deposition of two commercial pressurized metered dose inhalers (pMDIs) to determine their optimal inhalation patterns. Sultanol® inhaler (drug particles suspended in a propellant, suspension-pMDI) and QVAR™ (drug dissolved in a propellant with ethanol, solution-pMDI) were used as model pMDIs. Aerodynamic properties of the two pMDIs were determined using an Andersen cascade impactor with human inhalation flow simulator developed by our laboratory. As indices of peripheral-airway drug deposition, fine particle fractions (FPFPA) at different inhalation flow rates were calculated. The time-dependent particle diameters of sprayed drug particles were determined by laser diffraction. On aerodynamic testing, FPFPA of suspension-pMDI significantly decreased depending on the increasing inhalation flow rate, while solution-pMDI achieved higher and constant FPFPA in the range of the tested inhalation flow rates. The particle diameter of solution-pMDI markedly decreased from 5 to 3μm in a time-dependent manner. Conversely, that of suspension-pMDI remained at 4μm during the spraying time. Although "slow inhalation" is recommended for pMDIs, airway drug deposition via solution-pMDI (extra-fine particles) is independent of patients' inhalation flow pattern. Clinical studies should be performed to validate instruction for use of pMDIs for each inhaler for the optimization of inhalation therapy.

Ameliorative Effects of PGPB on Yield, Physiological Parameters, and Nutrient Transporter Genes Expression in Barattiere (Cucumis melo L.)

The intensive application of chemical fertilizers to overcome deficiency of nutrients and achieve maximum agricultural productivity has led to environmental impacts. A significant strategy for sustainable management, by decreasing the use of chemical fertilizers, can consist in the technology based on suitable levels of fertilization in combination with plant growth-promoting bacteria (PGPB) inoculation. This work aimed to test in vivo a consortium of three PGPB, previously isolated and characterized in vitro, on Barattiere plants (Cucumis melo L.). Plants were grown in a soilless system at the commercial dose of mineral fertilizer and at half dose, in order to evaluate the effects of these microorganisms on plant physiology, yield, and the transcriptional expression of four genes involved in NH4+ (AMT2), Fe (FRO, IRT1), and Pi (PHT1) transport and uptake by plant. Our results indicate that even in a soilless pot experiment, where a mineral nutrition solution is used, the bacterial consortium of PGPB improves fruit yield and early maturity, some physiological parameters, and upregulates the expression of some key genes related to N, Fe, and Pi plant nutrition, remarking the environmental and economic gains deriving from the use of half dose of mineral fertilizer.

SELECTIVITY OF THE HERBICIDE CHLORIMURON ETHYL ON YOUNG COFFEE PLANTS

The great interference of weeds in coffee plants, due to competition for water, light and nutrients, makes their control essential. Among these control methods, the chemical stands out, due to its high efficiency and low cost. However, as a function of application failures, phytotoxicity is frequent in coffee plants due to herbicide drift. Aiming to search for active ingredients selective to coffee, the objective of this study was to evaluate the selectivity of the active ingredient Chlorimuron ethyl in coffee seedlings, and its effects on plant morphology, anatomy and physiology. The experiment was carried out in a greenhouse with ‘Topázio MG 1190’ coffee plants (<em>Coffea arabica</em> L.), grown in 11-L pots. The statistical design was in randomized blocks, with four replications and four herbicide doses. Each plot consisted of three plants. The treatments were: 0%; 50%; 100% and 200% of the recommended commercial dose of the herbicide Chlorimuron ethyl. Evaluations were performed at 120 days after treatment application. Morphological, physiological and anatomical characteristics were evaluated, besides possible phytotoxicity symptoms inherent to herbicide application. The herbicide Chlorimuron ethyl caused phytotoxicity symptoms in coffee seedlings, evidenced from the leaflet dose, through leaf deformation and cracking, with growth losses not exceeding 10%, but without damage to plant physiology and anatomy.

PHYTOTOXICITY AND GROWTH OF COFFEE PLANTS AS A FUNCTION OF THE APPLICATION OF HERBICIDE 2,4-D

Weed control in coffee is of great importance for there is a great interference, standing out the competition for water, light and nutrients. Among the control methods, chemical control is highlighted as a function of its efficiency. However, the incorrect application of herbicides may imply the occurrence of drift, resulting in damage to coffee development due to phytotoxicity. In this context, the objective of this study was to evaluate the symptoms and phytotoxicity effects caused by the herbicide 2,4-D drift on the morphological, physiological and anatomical characteristics of coffee seedlings. The experiment was carried out in a greenhouse with ‘Topázio MG1190’ coffee seedlings (<em>Coffea arabica</em> L.), planted in 11-L pots. A randomized block design with four treatments and four replicates was used. The treatments were: 0%; 10%; 25% and 50% of the recommended commercial dose of 2,4-D (2.5 L.ha<sup>-1</sup>). Each plot consisted of three plants. The evaluations were performed at 74 days after implantation. Morphological, physiological, anatomical and phytotoxicity symptoms were evaluated as a function of the simulated herbicide drift. Coffee seedlings intoxicated by the herbicide 2,4-D presented hyponastic, chlorosis, shriveling and leaf anomalies. In the orthotropic branch, bending was observed in its extension, besides thickening in the collar region; in the plagiotropic branch, cracking was observed. Herbicide drift negatively affects the development of coffee plants. The coffee physiology was affected as a function of herbicide drift, but without damage to the leaf anatomy.

SELECTIVITY OF FLUAZIFOP-P-BUTYL IN YOUNG COFFEE PLANTS

Weed control is fundamental in coffee cultivation due to their big interference, competing with the crop for water, light and nutrients. Among the control methods used, chemical control is highlighted, as a function of its high efficiency and low cost. However, due to application failures, herbicide drift phytotoxicity is common. Aiming at the search for selective active ingredients in coffee plants, the objective of this study was to evaluate the selectivity of the active ingredient Fluazifop-p-butyl in young coffee plants, and its effects on plant morphology, anatomy and physiology. The experiment was carried out in a greenhouse, with ‘Topázio MG 1190’ coffee plants (<em>Coffea arabica</em> L.), cultivated in pots with a capacity of 11 L substrate. The statistical design was randomized block design (RBD), with four replications and four doses of the herbicide, making up 16 experimental plots. Each plot consisted of three plants. The treatments were: 0%; 50%; 100% and 200% of the recommended commercial dose of the herbicide Fluazifop-p-butyl. The evaluations were performed at 120 days after application of the treatments. Morphological, physiological and anatomical characteristics were evaluated. Regardless of the evaluated characteristic, there was no difference between the doses of the herbicide. There were no visual phytotoxicity symptoms in the young coffee plants that received the herbicide Fluazifop-p-butyl. The growth of the coffee plants, as well as the physiological and anatomical characteristics, were not altered due to the application of the herbicide Fluazifop-p-butyl.

Benchmarking Monte-Carlo dose calculation for MLC CyberKnife treatments

BackgroundVendor-independent Monte Carlo (MC) dose calculation (IDC) for patient-specific quality assurance of multi-leaf collimator (MLC) based CyberKnife treatments is used to benchmark and validate the commercial MC dose calculation engine for MLC based treatments built into the CyberKnife treatment planning system (Precision MC).MethodsThe benchmark included dose profiles in water in 15 mm depth and depth dose curves of rectangular MLC shaped fields ranging from 7.6 mm × 7.7 mm to 115.0 mm × 100.1 mm, which were compared between IDC, Precision MC and measurements in terms of dose difference and distance to agreement. Dose distributions of three phantom cases and seven clinical lung cases were calculated using both IDC and Precision MC. The lung PTVs ranged from 14 cm3 to 93 cm3. Quantitative comparison of these dose distributions was performed using dose-volume parameters and 3D gamma analysis with 2% global dose difference and 1 mm distance criteria and a global 10% dose threshold. Time to calculate dose distributions was recorded and efficiency was assessed.ResultsAbsolute dose profiles in 15 mm depth in water showed agreement between Precision MC and IDC within 3.1% or 1 mm. Depth dose curves agreed within 2.3% / 1 mm. For the phantom and clinical lung cases, mean PTV doses differed from − 1.0 to + 2.3% between IDC and Precision MC and gamma passing rates were > =98.1% for all multiple beam treatment plans. For the lung cases, lung V20 agreed within ±1.5%. Calculation times ranged from 2.2 min (for 39 cm3 PTV at 1.0 × 1.0 × 2.5 mm3 native CT resolution) to 8.1 min (93 cm3 at 1.1 × 1.1 × 1.0 mm3), at 2% uncertainty for Precision MC for the 7 examined lung cases and 4–6 h for IDC, which, however, is not optimized for efficiency but used as a gold standard for accuracy.ConclusionsBoth accuracy and efficiency of Precision MC in the context of MLC based planning for the CyberKnife M6 system were benchmarked against MC based IDC framework. Precision MC is used in clinical practice at our institute.

Independent assessment of source transit time for the BEBIG SagiNova® cobalt-60 high dose rate brachytherapy afterloader.

Independent verification of transit time and the methodology employed in commercial high dose rate (HDR) afterloaders to compensate its effect is an important part of their commissioning and quality assurance. This study aimed to independently evaluate the Co-60 source transit time of the new BEBIG SagiNova® HDR afterloader unit by employing a dosimetric approach using a well-type ionization chamber. The source was placed at three dwell positions (DPs) to mimic a variety of clinical situations with different distances from the afterloader unit. The distances of the DPs to the afterloader were 129.37cm, 124.50cm and 118.57cm. Plans were generated using the SagiPlan® treatment planning system to produce 3, 5, 10, 15, 20, 30, 40, 60 and 120s dwell times (DTs). The residual transit times (following any possible system compensation) were assessed using the ESTRO-recommended approach of obtaining transit time compensation factors and another strategy established for teletherapy sources. The mean residual transit time depended on the distance between the afterloader and the DP, ranging from 0.43 to 1.10s. The transit dose contribution was case-specific, ranging from 0.4% for a 60s DT at the nearest DP to the afterloader up to 15.6% for a 3s DT at the furthest DP from the unit. The results show that currently SagiNova® afterloader does not apply transit time compensation and suggest a 0.2-0.5s compensation for each arrival and departure DP from/to the afterloader, depending on position in an 11cm active length.

Controle e susceptibilidade de capim-braquiária e capim-ruziziensis ao glyphosate e fluazifop-p-butil

Este estudo teve como objetivo avaliar o controle e susceptibilidade de capim-braquiária e capim-ruziziensis em crescimento inicial submetidos a diferentes doses dos herbicidas glyphosate e fluazifop-p-butil. Os tratamentos foram arranjados no esquema fatorial 2 × 6, com cinco repetições, sendo duas gramíneas: Brachiaria decumbens cv. Basilisk (capim-braquiária) e B. ruziziensis (capim-ruziziensis), e seis doses dos herbicidas: 0,00; 0,25; 0,50; 1,00; 1,5 e 2,00 vezes a dose comercial indicada pelos fabricantes. Aos 7, 15, 21 e 30 dias após aplicação dos herbicidas (DAA) foram avaliadas visualmente a intoxicação em capim-braquiária e capim-ruziziensis. O glyphosate causou intoxicação de 100% em plantas de capim-braquiária e capim-ruziziensis, mesmo na menor dose (90 g ha-1), podendo ser utilizado com eficiência para o controle dessas espécies no início de desenvolvimento. Foi observado que as plantas submetidas ao fluazifop-p-butil apresentaram rebrota apenas nas doses aplicadas até 100 g ha-1 para capim-braquiária e 50 g ha-1 para o capim-ruziziensis. Esses resultados confirmam a eficiência dessa molécula herbicida no controle dessas duas espécies a partir das doses de 200 g ha-1 e 100 g ha-1 para capim-braquiária e capim-ruziziensis, respectivamente.

Secondary Growth Control in Garlic With Post Emergency Herbicides

This study aimed to verify the effect of the herbicides in the secondary growth control, productivity, and quality in garlic. The treatments were 5 herbicides: Glyphosate; Etoxissulfurom; 2-nicotinic acid; Halossulfurom and Metsulfurom-methyl and 5 doses (0; 10; 15; 20 and 25% of the smallest dose recommended for control of the weed). The experimental design was a randomized block, with 3 repetitions. The following evaluations were made: the total and marketable yield of bulbs, a percentage of secondary growth in bulbs, the medium mass of commercial bulbs and the number of bulbils per bulb of the commercial production. Larger productivities total and marketable was observed for the herbicide Glyphosate, 13.93 t ha-1, and 13.16 t ha-1, with doses of 10.81% and 13.12% of the commercial dose, respectively. The smallest incidence of secondary growth 4.05% was observed for Glyphosate with 15.58% of the dose. The largest medium mass of commercial bulbs 35.75 g were observed for the herbicide Glyphosate with 15.83% of the dose. The herbicides 2-nicotínic acid and Metsulfurom-methyl reduced the total productivity in relation to the control treatment without herbicide application and they promoted little gain in commercial productivity. Some herbicides can control the secondary growth in vernalized garlic, however, are necessary appropriate doses applied 50 days after the planting.

Efficacy of oral fluralaner for the treatment of canine generalized demodicosis: a molecular-level confirmation

BackgroundCanine generalized demodicosis is a common parasitic disease caused by the proliferation of Demodex mites. The introduction of isoxazoline class treatments in veterinary dermatology has resulted in apparently effective treatment of generalized demodicosis. The objective of this study was to evaluate the effectiveness of fluralaner for the treatment of canine generalized demodicosis using real-time PCR for the detection and quantification of Demodex DNA.MethodsTwenty privately owned dogs with clinical symptoms of generalized demodicosis and deep skin scrapings positive for Demodex canis mites were enrolled in the study. Following diagnosis (day 0) each dog was treated with fluralaner at the recommended commercial dose for tick and flea treatment (25–56 mg/kg) based on body weight. Clinical and mite count assessments, and hair sampling for molecular analyses were performed on days 0, 28, 56, 84 and 112. Demodex DNA was detected and quantified using real-time PCR.ResultsA single oral dose of fluralaner reduced Demodex mite counts in skin scrapings by an average of 98.9% in all dogs by day 28. No mites were recovered from skin scrapings from any treated dog by day 56, at which time the dog was considered to be clinically cured, with total hair regrowth. There were significant differences among examined dogs in qPCR cycle threshold (Ct) values on days 0, 28, 56, 84 and 112. Demodex DNA levels decreased (increasing Ct values) throughout the study. Mite DNA was present on day 112, possibly from dead mites, at values significantly lower than in samples taken on days 0, 28 and 56. Based on qPCR testing of diluted samples, the Demodex mite population was reduced by approximately 1000-fold on day 112.ConclusionsOral administration of fluralaner at the recommended dose to dogs with generalized demodicosis is highly effective for reducing Demodex mite populations and resolving clinical signs of generalized demodicosis. The presence of mite DNA may indicate that treatment did not kill all Demodex mites.

SUCROSE IN DETOXIFICATION OF COFFEE PLANTS WITH GLYPHOSATE DRIFT

<p class="Normal-UFLA"><span lang="EN-US">The weed’ control in coffee plants has great importance, as they compete for light, water and nutrients. The chemical control is the most used, emphasizing the glyphosate, however, when applied, drift can occur and consequently cause injuries to coffee. Many farmers use the sucrose application with the objective to reverse the damage caused by the herbicide drift, even without scientific basis to justify such action. The objective of this study was to evaluate the effect of the sucrose application on the detoxification of coffee plants in the implantation phase with glyphosate drift. The experiment was conducted in a greenhouse, using a randomized block design, arranged in a 3 x 3 factorial scheme with 2 additional treatments, using 3 sucrose doses (2, 4 and 8%) with 3 application times (1, 24 and 168 hours after intoxication with 10% of the commercial glyphosate dose) with an additional one in which the plants were not intoxicated and not treated with sucrose and the other additional only with plants intoxicated by glyphosate. After 75 days conducting the experiment, growth, physiological and anatomical characteristics were evaluated. The application of sucrose in the reversal of intoxication of growth variables (height, leaf areaThe objective of this study was to evaluate the effect of the sucrose application on the detoxification of coffee plants in the implantation phase with glyphosate drift. number of leaves, shoot dry weight and dry weight of the root system) was not efficient. For the physiological variables the application of 2% sucrose, one hour after glyphosate intoxication was the most efficient treatment.</span></p>

GROWTH, ANATOMY AND PHYSIOLOGY OF COFFEE PLANTS INTOXICATED BY THE HERBICIDE GLYPHOSATE

<p>Weed control is fundamental in coffee cultivation due to their high interference, competing with the crop for water, light and nutrients. Among the control methods used, chemical control is highlighted, due to its high efficiency and low cost. However, due to application failures, herbicide drift phytotoxicity is common. Aiming at the search for selective active ingredients in coffee, the objective of this study was to evaluate the selectivity of the active ingredient Glyphosate in young coffee plants. The experiment was carried out in a greenhouse with ‘Topázio MG1190’ coffee plants (<em>Coffea arabica</em> L.), cultivated in pots with an 11 L-substrate capacity. The statistical design was RBD, with four replications and four doses of the herbicide, making up 16 experimental plots. Each plot consisted of three plants. The treatments were: (i) 0%; (ii) 10%; (iii) 25% and (iv) 50% of the commercial dose of the herbicide Glyphosate. The evaluations were performed at 104 days after application of the treatments. Growth, morphological, physiological and anatomical characteristics were evaluated. The collected data were analyzed using the SISVAR software. The effect of glyphosate drift impairs plant growth. However, after 104 days of intoxication, there is no longer any effect on the physiology and leaf anatomy of coffee trees.</p>

Construction of patient-specific computational models for organ dose estimation in radiological imaging.

Diagnostic imaging procedures require optimization depending on the medical task at hand, the apparatus being used, and patient physical and anatomical characteristics. The assessment of the radiation dose and associated risks plays a key role in safety and quality management for radiation protection purposes. In this work, we aim at developing a methodology for personalized organ-level dose assessment in x-ray computed tomography (CT) imaging. Regional voxel models representing reference patient-specific computational phantoms were generated through image segmentation of CT images for four patients. The best-fitting anthropomorphic phantoms were selected from a previously developed comprehensive phantom library according to patient's anthropometric parameters, then registered to the anatomical masks (skeleton, lung, and body contour) of patients to produce a patient-specific whole-body phantom. Well-established image registration metrics including Jaccard's coefficients for each organ, organ mass, body perimeter, organ-surface distance, and effective diameter are compared between the reference patient model, registered model, and anchor phantoms. A previously validated Monte Carlo code is utilized to calculate the absorbed dose in target organs along with the effective dose delivered to patients. The calculated absorbed doses from the reference patient models are then compared with the produced personalized model, anchor phantom, and those reported by commercial dose monitoring systems. The evaluated organ-surface distance and body effective diameter metrics show a mean absolute difference between patient regional voxel models, serving as reference, and patient-specific models around 4.4% and 4.5%, respectively. Organ-level radiation doses of patient-specific models are in good agreement with those of the corresponding patient regional voxel models with a mean absolute difference of 9.1%. The mean absolute difference of organ doses for the best-fitting model extracted from the phantom library and Radimetrics™ commercial dose tracking software are 15.5% and 41.1%, respectively. The results suggest that the proposed methodology improves the accuracy of organ-level dose estimation in CT, especially for extreme cases [high body mass index (BMI) and large skeleton]. Patient-specific radiation dose calculation and risk assessment can be performed using the proposed methodology for both monitoring of cumulative radiation exposure of patients and epidemiological studies. Further validation using a larger database is warranted.

Laboratory and field survival of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Bt and non-Bt maize and its susceptibility to insecticides.

Field-evolved resistance of fall armyworm (FAW), Spodoptera frugiperda (Smith), has been reported to Bt maize technologies in Brazil. The control failures of FAW by Bt maize increased the use of insecticides for their control. However, no information is available on the interaction between resistant FAW and their response to insecticides. Here, we evaluated the survival of FAW strains on Bt and non-Bt maize in laboratory and field conditions, and their susceptibility to insecticides. In the laboratory, resistant FAW larvae reared on Bt and non-Bt maize showed a similar susceptibility to spinetoram (LC50 = 0.16-0.18 µg a.i. cm-2 ) and chlorfenapyr (LC50 = 0.17-0.20 µg a.i. cm-2 ). However, their susceptibility was lower than that of the susceptible strain reared on non-Bt maize: LC50 = 0.05 (spinetoram) and 0.08 (chlorfenapyr) µg a.i. cm-2 . In contrast, heterozygous strains had similar susceptibility to the susceptible strain. In field trials, no differences in FAW survival were detected between strains when the commercial dose of two insecticides was applied in Bt and non-Bt maize. FAW strains surviving on Bt and non-Bt maize, at the same development stage, have similar susceptibility to insecticides. The integrated pest management practices and insect resistance management importance of these results are discussed. © 2019 Society of Chemical Industry.

Development of optical fibers for food irradiation dosimeter

Different technologies and methods for enhancing food quality have been developed and applied in the last few decades. One of the latest technologies is by using ionizing radiation. Food irradiation is the technology that improves the safety and extends the shelf life of food by reducing or eliminating harmful microorganisms and insects. In order to provide for food safety, proper control or radiation detector of irradiated food seems very critical to facilitate international trade of irradiated foods and to enhance consumer confidence. In present studies, germanium-doped (Ge-doped) optical fibers of various form and dimensions were used as radiation detector. The fibers were irradiated using electron beam (EPS 3000), with doses from 1 kGy up to 10 kGy, exceeding the dose range of all commercial high dose dosimeters used in food irradiation industry. A study has been made of linearity, reproducibility, and fading. The fibers show a linear dose response over the studied range doses with mean of reproducibility less than 5 % variation between 1st exposure and 2nd exposure. TL fading of Ge-doped flat fibers has been found to be < 8.7%.

Efficacy of orally administered fluralaner in dogs against laboratory challenge with Haemaphysalis longicornis ticks

BackgroundHaemaphysalis longicornis ticks represent an ectoparasitic health threat to dogs. This study evaluated the immediate and persistent efficacy of orally administered fluralaner for control of this tick.MethodsTwenty-four dogs were sorted into 4 groups based on their tick carrying capacity measured in a preliminary challenge. Two days before treatment, dogs were challenged with Haemaphysalis longicornis and then at the time of treatment dogs received with oral fluralaner at 10, 25 or 50 mg/kg respectively to 3 of the groups, while the remaining group was sham treated. Ticks were counted and categorized on all dogs 2 days after treatment (4 days after challenge). Tick challenges were repeated at 28, 56, 84 and 112 days following treatment with tick counts 48 hours following each challenge. Tick control efficacy was evaluated by comparing the mean (geometric) total live attached and dead engorged ticks on each fluralaner treated group with the sham treated dogs.ResultsOral fluralaner is highly acaricidal for H. longicornis that feed on treated dogs. The mean efficacy rate in dogs treated with fluralaner at the commercial dose range of 25 to 50 mg/kg was greater than 90% at 114 days after treatment, whereas efficacy at this time in dogs treated at 10 mg/kg was 79%.ConclusionsFluralaner administered orally to dogs within the commercial dose range at 25 to 50 mg/kg is effective for up to 114 days against laboratory challenge with H. longicornis ticks.

Effects of Herbicides on the Survival of the Brazilian Native Bee Melipona scutellaris Latreille, 1811 (Hymenoptera: Apidae)

ABSTRACT: Native bees are key pollinators to native and cultivated plants. Understanding the effects of the products used in crops on bees is crucial and can help establish management measures that offer more protection. The aim of this study was to evaluate the influence of the 1/2 the commercial dose; the commercial dose (2,4-D 1,000 g a.i. ha-1, glyphosate 760 g a.i. ha-1, glyphosate + 2,4-D 760 g a.i. ha-1 + 1,000 g a.i. ha-1, and picloram 2% (v/v) and 2x the commercial dose of glyphosate, 2,4-D, picloram, and glyphosate+2,4-D on the survival of bees Melipona scutellaris by contact and oral exposure. We also evaluated the impact of herbicides used in semi-field realistic conditions on temperature control and weight of colonies of M. scutellaris. The results show that there was no decrease in longevity when half of the recommended field dose was applied. When field dose was used, topically exposed bees to glyphosate + 2,4-D had a decrease in longevity. In oral exposure both to the recommended field dose and the double dose, bees had reduced longevity, except those exposed to a double dose of 2,4-D. In semi-field conditions, there were no differences between control and exposure colonies. The data presented indicate that the herbicides may affect bees directly compromise their survival and indirectly they might affect the process of pollination.

Transport of Atrazine Via Leaching in Agricultural Soil with Mineral Oil Addition

ABSTRACT: Adjuvants, such as mineral oils, are widely used in the application of herbicides by reducing the drift and evaporation of the droplets and by increasing herbicide uptake by the plant. However, little is known about how mineral oil behaves when in contact with the soil. Thus, the objective of this research was to evaluate the transport of atrazine via leaching with the addition of mineral oil in a soil agricultural under laboratory conditions. To quantify the concentration of the herbicide along the profile of the very clay soil column (30 cm), 14C-atrazine (ring-U-14C) was used with 16,667 Bq of radioactivity per column in volume of 200 mL solution and 0 (control), 1, and 2% mineral oil (v/v) was added in the application volume. Atrazine was applied at the highest commercial dose recommended for sugarcane (4 kg ha-1). After simulation of a precipitation of 200 mm for 48 h, each column was sectioned into six parts of 5 cm and the analytes of each soil sample and the leachate were quantified by liquid scintillation spectrometry. The atrazine remained in the superficial layer of the soil, between 0 and 10 cm of depth, independent of the addition of mineral oil. No atrazine residues were detected in the leachate solution (> 30 cm) in any evaluated treatment. The addition of mineral oil at the time of application of pre-emergence atrazine did not interfere with the transport of this herbicide in the soil profile agricultural via leaching; therefore, the adjuvant may have positive effect only in the herbicide-plant relationship.

Effectiveness of reduced doses of flumioxazin herbicide at weed control in direct sow onions

The recommended application of most herbicides in onion crops is after transplanting seedlings with four true leaves. In the direct sowing system, this recommendation is considered late; an alternative management is the application of reduced doses starting with a true leaf. The objective of this study was to evaluate the use of reduced doses of flumioxazin in the early phenological stages of onions on bulb yield. Two field experiments were installed, and five doses of flumioxazin (5, 10, 15, 20, and 25 g ha-1) were applied in three phenological stages (1st, 2nd, and 1st+3rd true leaf); weed control was carried out. The results demonstrated the efficacy of reduced doses of flumioxazin on onion crop in the early stages. The dose of 20 g ha-1 showed use potential in the two experiments for the cvs. Perfecta and Sirius, enabling reductions of 77 to 88% of the commercial dose recommended for onions established with seedling transplanting. The application of flumioxazin in the 2nd leaf reduced commercial productivity and was ineffective in the control of weeds. The application in the 1st + 3rd leaf, despite being an effective control, caused greater phytotoxicity and, therefore, reduced commercial productivity. The best strategy for weed management is 20 g ha-1 flumioxazin applied to onion plants when they reach the true first leaf stage.

High Risk Fungicides Combined to Low Risk Can Be a New Strategy for Management of Asian Soybean Rust at the Beginning of the Epidemic

Asian soybean rust (ASR) caused by Phakopsora pachyrhizi since it was first reported in Brazil in 2001 has been subject of studies regarding the use of fungicides to its control. Low efficiency of triazol (demethylator inhibitors-DMI’s) or stobilurin (quinone outside inhibitor-QoI’s) has been reported on the control of ASR under field conditons. For this reason experiments were conducted to study the effects of these systemic fungicides associate with protectant multi-site fungicides (MSF) on ASR control preventively and at the onset of the epidemic. All combinations of fungicides were effective to control ASR and promoted greater soybean yield gain compared to the control. The analysis of the efficacy of ASR control in the lower, medium and upper part of the plant canopy, showed that application of Epoxiconazole + Pyraclostrobin and Cyproconazole + Azoxystrobin reduced ASR and leaf fall (%), and increased soybean yield grain. The severity of the disease increased from the lower to the upper part of the plant. The application of DMI+ QoI associated with MSF applyed when disease severity reached 2%, promoted effective reduction of ASR, increased yield and reduced leaf fall. Overal the DMI’s + QoI’s associated with MSF was 68% and 70.2% more efficient on ASR control and soybean grain yield, respectively than the control. Mancozeb and Chlorothalonil associated with the lowest dose of Epoxiconazol + Pyraclostrobin (10.2 + 33.2 g.a.i./ha) or Cyproconazole + Azoxystrobin (12.5 + 30.0 g.a.i./ha), respectively increased soybean grain yield at least 45.0%; the same combinations of the fungicides Epoxiconazol + Pyraclostrobin (15.3 + 49.8 g.a.i./ha) and Cyproconazole + Azoxystrobin (25.0 + 60.0 g.a.i./ha) 50% less than the commercial dose, increased 89.5% and 109.0%, respectively. The use of high risk (DMI and QoI) fungicides combined to low risk (MSF) applyied properly, can be a new strategy for the management of ASR at short and long term, even after the epidemics has reached 2.0% severity. Furthermore, due to the residual effect, MSF can promote higher longevity of DMI and QoI molecules.