Carrier Volume Research Articles

Efficacy of Saflufenacil for Dry Bean and Annual Weed Desiccation

The efficacy of saflufenacil for desiccating dry bean and annual weeds may be influenced by application rate, single or sequential applications, adjuvant selection and rate, and water carrier volume. Five field experiments were conducted from 2021 to 2023 near Exeter and Ridgetown, Ontario, Canada to evaluate the efficacy of saflufenacil applied at two rates, applied once or sequentially, with four adjuvants at various rates, and three water carrier volumes for desiccating dry bean and common weed escapes in Ontario dry bean production. Saflufenacil (25 g ai ha-1) + Merge (1.0 L ha-1) applied with a 200 L ha-1 water carrier volume desiccated dry bean 96, 100, and 100% at 5, 8, and 14 days after application (DAA), respectively; there was no improvement in dry bean desiccation by increasing the rate of Merge to 2.0 L ha-1 or with a sequential application. With saflufenacil (50 g ai ha-1) + Merge (1.0 L ha-1), there was no impact on dry bean desiccation with water carrier volumes of 100, 200, or 300 L ha-1. Dry bean desiccation with saflufenacil (50 g ai ha-1) plus the adjuvants Merge, MSO, AMS, or Merge + AMS was similar. Sequential applications of saflufenacil (25 g ai ha-1) applied twice at a 1-week interval did not improve dry bean desiccation. For weed species desiccation, saflufenacil + Merge desiccated green pigweed (38-100%) and common ragweed (65-96%) most effectively. However, it was less effective on common lambsquarters (0-48%), barnyardgrass (9-24%), and green foxtail (6-14%), with no significant effect of saflufenacil rate, adjuvant selection, adjuvant rate, single vs sequential application, or water carrier volume. This study highlights the potential and limitations of saflufenacil for desiccating dry bean and common weed escapes in Ontario dry bean production.

Increasing Analytical Quality by Designing a Thin-Layer Chromatography Scanner Method for the Determination of the Radiochemical Purity of Radiopharmaceutical Sodium Iodide 131I Oral Solution.

The goal of this study was to apply the principles of analytical quality by design (AQbD) to the analytical method for determining the radiochemical purity (PQR) of the radiopharmaceutical sodium iodide 131I oral solution, utilizing thin-layer chromatography (TLC) with a radio-TLC scanner, which also enables the evaluation of product quality. For AQbD, the analytical target profile (ATP), critical quality attributes (CQA), risk management, and the method operable design region (MODR) were defined through response surface methodology to optimize the method using MINITAB® 19 software. This study encompassed the establishment of a control strategy and the validation of the method, including the assessment of selectivity, linearity, precision, robustness, detection limit, quantification limit, range, and the stability of the sample solution. Under the experimental conditions, the method parameters of the TLC scanner were experimentally demonstrated and optimized with an injection volume of 3 µL, a radioactive concentration of 10 mCi/mL, and a carrier volume of 40 µL. Statistical analysis confirmed the method's selectivity for the 131I iodide band Rf of 0.8, a radiochemical impurity IO3- Rf of 0.6, a linearity from 6.0 to 22.0 mCi/mL, and an intermediate precision with a global relative standard deviation (RSD) of 0.624%. The method also exhibited robustness, with a global RSD of 0.101%, a detection limit of 0.09 mCi/mL, and a quantification limit of 0.53 Ci/mL, meeting the prescribed range and displaying stability over time (at 0, 2, and 20 h) with a global RSD of 0.362%, resulting in consistent outcomes. The development of a method based on AQbD facilitated the creation of a design space and an operational space, with comprehensive knowledge of the method's characteristics and limitations. Additionally, throughout all operations, compliance with the acceptance criteria was verified. The method's validity was confirmed under the established conditions, making it suitable for use in the manufacturing process of sodium iodide 131I and application in nuclear medicine services.

Pickering emulsions constructed on the basis of nanostructured lipid carriers: Effect of carrier models and volume fractions

Three types of curcumin-loaded nanostructured lipid carriers with a single layer (S-NLCs), double layer (D-NLCs) and composite layer (C-NLCs) were used as stabilizers for the preparation of Pickering emulsions. Visual observations showed that the NLCs stabilized the Pickering emulsions at different addition volume fractions. The emulsions produced had approximate particle size and showed an inversion of the emulsions stabilized by D-NLCs and C-NLCs as the additional fraction of NLCs was increased to 50%. Contact angles and interfacial viscoelasticity showed a better wetting of D-NLCs with a superior ability to reduce surface tension at the oil–water interface. Pickering emulsions stabilized at a 50% volume ratio (PD5) showed the highest storage and centrifugal stability. Simulated in vitro digestion studies showed the presence of delayed lipid digestion of Pickering emulsions, resulting in the incomplete release of curcumin and lower bioavailability than NLCs under the same conditions.

A comprehensive study of spray coating technique parameters and chemical postdeposition treatments for transparent conducting SWCNT thin films

The demands for transparent conducting films (TCFs) are continuously increasing and the future of this industry is going toward large scale, cheap and mechanically stable electronics. This study shows a simple way to fabricate low-cost transparent conductive single-walled carbon nanotube (SWCNT) thin films by spray coating. The work employed here demonstrates that it is possible to fabricate highly efficient SWCNT TCFs without the use of expensive ultrasonic spray coating equipment. Highly conductive TCFs were prepared by dispersing SWCNTs in an N-Methyl-2-pyrrolidone (NMP) solution. The spray coated TCF properties were studied by the effect of spray gun carrier gas pressure, concentration, and volume sprayed onto the substrates. The prepared thin films were subjected to post treatments with nitric acid (HNO3) using different treatment methods and times in order to improve the electrical conductivity. To further investigate the effect of p-doping in SWCNT thin films, HNO3 treatments were combined with thionyl chloride (SOCl2). The experimental results indicated that spray coating is an effective method to obtain highly conductive films without any chemical treatment, resulting in 273 Ω/sq sheet resistance, at 84% in the visible range. Additionally, the optimized films treated with both HNO3 and HNO3/SOCl2 showed great improvements at 83%–85% in the visible range and in sheet resistances followed by 98 and 103 Ω/sq with very good FOM values (1.6 × 10−3 and 2 × 10−3, respectively).

Palmer Amaranth (Amaranthus palmeri) Control in Dicamba-Tolerant Cotton (Gossypium hirsutum) when Applied with Various Dicamba + Insecticide Tank-Mixtures

Postemergence herbicide application timings for Palmer amaranth (Amaranthus palmeri) often coincide with foliar insecticide applications in cotton (Gossypium hirsutum). Combining multiple pesticides into a single application increases efficiency while reducing overall application cost. Multiple foliar insecticides are now labeled for dicamba tank-mixes. However, there is limited literature with respect to efficacy of dicamba on Palmer amaranth control when applied with insecticides. Field experiments were conducted from 2018 to 2020 to evaluate the effect of carrier volume and insecticide on the efficacy of dicamba (XtendiMaxTM with VaporGripTM) to control Palmer amaranth in XtendFlex™ cotton production systems. Dicamba was tank-mixed with acephate and dimethoate to four-leaf cotton and with thiamethoxam and sulfoxaflor just prior to bloom. Applications were made at carrier volumes of 140 and 280 L ha-1 and with a single spray droplet size of 800 µm. Palmer amaranth control 7 d after treatment was negatively impacted when applications included dimethoate; however, no corresponding response in seedcotton yield was observed relative to dicamba applied alone. However, when pooled over carrier volume, applications containing dicamba + acephate resulted in higher seedcotton yield than applications of dicamba + dimethoate. Additionally, pre-bloom applications of dicamba + thiamethoxam or sulfoxaflor increased Palmer amaranth efficacy relative to dicamba applied alone. Although certain insecticides are known to increase herbicidal crop response, the impact of insecticides on herbicide efficacy to control specific weed species is largely unknown. Therefore, we conclude that multiple dicamba + acephate, thiamethoxam, or sulfoxaflor tank-mixtures provide similar control of Palmer amaranth compared to dicamba alone.

Factors influencing subcanopy leaf and stolon exposure and associated absorption and translocation of herbicides in semidormant zoysiagrass

AbstractTurfgrass managers are concerned about zoysiagrass (Zoysia japonica Steud.) injury from nonselective herbicide treatment during winter dormancy. Research was conducted to assess factors affecting spray penetration into semidormant ‘Meyer’ zoysiagrass canopies and to evaluate absorption and translocation of [14C]glyphosate and [14C]glufosinate into green leaves and subtending stolons. Absorption of [14C]glyphosate and [14C]glufosinate was up to four times greater in stolons than in leaves. Zoysiagrass leaves treated with [14C]glufosinate had more rapid 14C absorption than those treated with [14C]glyphosate. More 14C translocated out of the treated area following [14C]glyphosate treatment compared with [14C]glufosinate and moved more readily from stolon to leaves than from leaves to stolon. When extended-range, flat-fan spray tips (XR) were positioned 61 cm above zoysiagrass, 73% and 11% of recovered colorant was extracted from dormant vegetation in the upper and lower canopy levels. Turbo TeeJet® spray tips (TTI) deposited fewer droplets into the upper canopy and more droplets into the middle and lower canopy regardless of position above the turf surface. Increasing pressure from 103 to 414 kPa increased droplet velocities from XR and TTI nozzles and decreased droplet diameters of XR nozzles. Droplet diameters were also substantially increased when using TTI nozzles compared with XR nozzles. Droplet diameter and associated mass were more determinant of turfgrass canopy penetration than droplet velocity. At 60 L ha−1 of carrier volume, 23% of colorant reached the lower canopy level, and this quantity increased by 2.3% per additional 100 L ha−1. When carrier volume was reduced from 584 to 60 L ha−1, 48% less colorant was delivered to the lower canopy level. Given that subcanopy stolons are always present and absorb more glyphosate and glufosinate than leaves, practices such as avoiding induction-type nozzles, raising spray height, and reducing spray volume can reduce herbicide delivery and potential injury to semidormant zoysiagrass.

Urea ammonium nitrate as the carrier for preplant burndown herbicides

AbstractPreplant weed control is a common practice for many small grain farmers. The timing of these applications often coincides with starter nitrogen (N) fertilizer application. Co‐application of the herbicides and N fertilizers, such as urea‐ammonium nitrate (UAN), can reduce the number of trips across the field, labor costs, and the costs of N and herbicide applications. However, there is a dearth of information on the effect of herbicide‐N fertilizer mixtures on herbicide efficacy. Field studies were conducted in the summer of 2021 and 2022 to evaluate the effect of UAN (32‐0‐0) rate (0%, 25%, 50%, 75%, and 100% of carrier volume) on the efficacy of three non‐selective herbicides (glyphosate [1260 g ae ha−1], paraquat [560 g ai ha−1], and tiafenacil [74 g ai ha−1]). There was no effect of UAN volume on herbicide efficacy. The addition of UAN did not reduce the efficacy of glyphosate, paraquat, or tiafenacil. At 3 weeks after herbicide application, glyphosate efficacy ranged from 92% to 94% (broadleaved weeds) and 97% (grassy weeds). Paraquat efficacy ranged from 63% to 87% (broadleaved weeds) and 87% (grassy weeds). Tiafenacil efficacy ranged from 52% to 74% (broadleaved weeds) and 70% (grassy weeds). Higher application volume may be needed to increase the efficacy of contact herbicides such as paraquat and tiafenacil.

Low carrier volume herbicide trials and UAAS support management efforts of giant salvinia (Salvinia molesta): a case study

AbstractExpanding the current aquatic herbicide portfolio, reducing total spray volumes, or remotely delivering herbicide using novel spray technologies could improve management opportunities targeting invasive aquatic plants, where options are more limited. However, research on giant salvinia (Salvinia molesta Mitchell) response to foliar herbicide applications at carrier volumes ≤140 L ha−1 is incomplete. Likewise, no data exist documenting S. molesta control with unoccupied aerial application systems (UAAS). Following the recent >100-ha incursion of S. molesta in Gapway Swamp, NC, a case study was developed to provide guidance for ongoing management efforts. In total, three field trials evaluated registered aquatic and experimental herbicides using a 140 L ha−1 carrier volume. Select foliar applications from UAAS were also evaluated. Results at 8 wk after treatment (WAT) indicated the experimental protoporphyrinogen oxidase inhibitor, PPO-699-01 (424 g ai ha−1), in combination with endothall dipotassium salt (2,370 g ae ha−1) provided 78% visual control, whereas control when PPO-699-01 (212 g ai ha−1) was applied alone was lower at 35%. Evaluations also showed diquat (3,136 g ai ha−1) alone, glyphosate (4,539 g ae ha−1) alone, and metsulfuron-methyl (42 g ai ha−1) alone achieved 86% to 94% visual plant control at 8 WAT. Sequential foliar applications of diquat, flumioxazin (210 g ai ha−1), and carfentrazone (67 g ai ha−1) at 6 wk following exposure to in-water fluridone treatments were no longer efficacious by 6 WAT due to plant regrowth. Carfentrazone applications made from a backpack sprayer displayed greater control than applications made with UAAS deploying identical carrier volumes at 2 WAT; however, neither application method provided effective control at 8 WAT. Additional field validation is needed to further guide management direction of S. molesta control using low carrier volume foliar applications.

Sethoxydim performance on torpedograss (Panicum repens) and sand cordgrass (Spartina bakeri) as affected by carrier volume and rate

AbstractGreenhouse experiments were conducted in 2020 to investigate the effects of carrier volume and sethoxydim rate on torpedograss (Panicum repens L.) control and sand cordgrass (Spartina bakeri Merr.) response from a single application. Panicum repens control and biomass reduction generally increased with increasing sethoxydim rates in evaluations at 14, 28, and 42 d after treatment (DAT); however, increasing the rate to 2X the maximum labeled rate did not always result in increased efficacy. In the first experimental run, which consisted of small plants, P. repens control and biomass reductions were largely similar among tested carrier volumes (37, 187, and 935 L ha−1). However, in run 2, which consisted of larger, mature P. repens plants, efficacy increased when carrier volume was reduced. Spartina bakeri injury increased with sethoxydim rate, reaching a maximum of 45% by 42 DAT. However, no differences in S. bakeri injury among carrier volumes were observed at 14 and 28 DAT evaluations. Spartina bakeri aboveground biomass reductions were also largely driven by sethoxydim rate increases rather than reduced carrier volumes, reaching 40% to 50% reduction in initial aboveground biomass. However, S. bakeri belowground biomass was 20% to 32% greater in treatments applied at 37 or 187 L ha−1 compared with those at 935 L ha−1. Overall, these data suggest that selective P. repens control with sethoxydim may be enhanced through reducing carrier volumes from 935 L ha−1 and that native, perennial, caespitose grasses may exhibit greater tolerance to sethoxydim compared with the rhizomatous P. repens. Future research should further test these hypotheses under field conditions at operational scales.

Evaluation of PVC-Type Insulation Foam Material for Cryogenic Applications

With the International Maritime Organization (IMO) reinforcing environmental regulations on the shipbuilding industry, the demand for fuels, such as liquefied natural gas (LNG) and liquefied petroleum gas (LPG), has soared. Therefore, the demand for a Liquefied Gas Carrier for such LNG and LPG also increases. Recently, CCS carrier volume has been increasing, and damage to the lower CCS panel has occurred. To withstand liquefied gas loads, the CCSs should be fabricated using a material with improved mechanical strength and thermal performance compared with the conventional material. This study proposes a polyvinyl chloride (PVC)-type foam as an alternative to commercial polyurethane foam (PUF). The former material functions as both insulation and a support structure primarily for the LNG-carrier CCS. To investigate the effectiveness of the PVC-type foam for a low-temperature liquefied gas storage system, various cryogenic tests, namely tensile, compressive, impact, and thermal conductivity, are conducted. The results illustrate that the PVC-type foam proves stronger than PUF in mechanical performance (compressive, impact) across all temperatures. In the tensile test, there are reductions in strength with PVC-type foam but it meets CCS requirements. Therefore, it can serve as insulation and improve the overall CCS mechanical strength against increased loads under cryogenic temperatures. Additionally, PVC-type foam can serve as an alternative to other materials in various cryogenic applications.

Deposition aids, nozzle selection and carrier volume on canopy deposition and management of Cercospora leaf spot in sugarbeet (Beta vulgaris L.)

Cercospora leaf spot (CLS; Cercospora beticola Sacc.) is an economically devastating disease of sugarbeet (Beta vulgaris L.) in many regions worldwide. Field experiments evaluated the potential of InterLock deposition aid (MVO) and carrier volumes of 115, 235, 350, and 470 L ha−1 for improved CLS management with mancozeb (Manzate Pro-Stick) under moderate CLS intensity. Adding MVO to mancozeb did not reduce disease accumulation or improve yield or sugar quality more than mancozeb alone. Increased carrier volume did not affect disease progression but had a neutral effect on profit margin. Additional field experiments investigated the effect of MVO on spray deposition by analyzing Rhodamine WT recovery from leaves. Using MVO with mancozeb did not improve canopy deposition compared to mancozeb alone, regardless of the nozzle or carrier volume tested. Canopy deposition was improved using Hardi® ISO injet™ nozzles compared to Teejet® XR110 and Teejet® AI3070® nozzles. A quadratic relationship between dye recovery and carrier volume (R2 = 0.2871 p=<0.0001) was found; applications using a carrier volume of 350 L ha−1 improved deposition compared to 115 and 235 L ha−1. While MVO did not improve CLS management when mixed with Manzate Pro-Stick, nozzle selection did influence canopy deposition, and effects on CLS development require further investigation. In this study, increased carrier volume was not beneficial in limiting disease progress but incurred no economic penalty. Given the generally positive correlation between fungicide efficacy and the quality/degree of spray coverage, increased carrier volume should still be considered a best practice in disease management at the carrier volumes tested.

Insecticidal Activity of a Petroleum-Derived Spray Oil and an Organosilicone Surfactant on Listronotus maculicollis (Kirby) Adults in Laboratory and Greenhouse Bioassays.

The annual bluegrass weevil (ABW), Listronotus maculicollis (Kirby), is a severe pest of golf course turf in eastern North America. The development of pyrethroid- and multiple-resistant populations has created a dire need for novel tactics to control adults. We examined the insecticidal properties of a petroleum-derived spray oil (PDSO; Civitas Turf Defense™.) and an organosilicone, nonionic soil surfactant (Silwet L-77®) in laboratory and greenhouse bioassays. Civitas and Silwet killed &gt; 75% of ABW adults in multiple assays. The level of control was positively affected by increased rate, spray application volume, and soil moisture levels. Dissections of weevils treated with Civitas revealed material entering the insect's hemocoel after 15-30 min, though most mortality occurred between the 3 and 24 h observation periods. Reducing rates while increasing carrier volume or soil moisture levels through irrigation applied prior to or after application also provided excellent control of adults in the same observation periods. Silwet provided comparable, yet less consistent levels of control in the laboratory studies but was excluded from further tests after treated plants demonstrated phytotoxicity in greenhouse studies. Neither Silwet nor Civitas efficacy was affected by pyrethroid resistance levels in the ABW populations tested.

Survey of pesticide application practices and technologies in Georgia agronomic crops

AbstractPesticide regulations and application technologies are changing rapidly due to rising concerns around off-target movement of pesticides and increased focus on improving the efficiency of pesticide applications. In order to conduct relevant applied research and develop educational programs related to pesticide application, it is necessary to understand the common application practices and technologies that growers use. A survey was conducted to assess common pesticide application practices and technologies used by Georgia growers. Both online and printed survey copies were distributed by county agricultural extension agents to growers in all 159 counties. A total of 186 responses representing agronomic crops in 65 counties were received and analyzed for results. Main results of this survey indicated that 1) 72% of respondents produced ≥200 ha of crops; 2) 29% of respondents received their information from university Extension personnel; 3) 42% of respondents used a separate sprayer for applications of dicamba, 2,4-D, or 2,4-DB; 4) 46% of respondents used sprayers with boom lengths ≥18.3 m; 5) 65% of respondents used ≥121 L/ha to apply pesticides; 6) 53% of respondents used three or more different nozzles on their spray booms throughout the season; 7) 68% of respondents used TeeJet® nozzles; 8) 65% of respondents used global positioning systems and rate controllers on their application equipment; 9) 66% of respondents recorded their pesticide application data on a notepad or diary; and 10) 39% of respondents reported that application accuracy is the biggest advantage of new spray technologies. Respondents also reported that weather, timing, and pesticide drift/regulations were their biggest application challenges and that more research is needed on topics such as rates, carrier volumes, pest control, chemicals and adjuvants. Information from this survey provides useful insights into the current application practices, technologies, and research needs of Georgia growers and will be used for developing appropriate research and educational efforts.

Application of Poly(Ethyl Eugenyl Oxyacetate) Compounds as the Ions Carrier for Heavy Metals Separation and Separation of Fe and Ni in Ferronickel Using Liquid Membrane Transport Method

Poly(ethyl eugenyl oxyacetate) (PEEOA) had been synthesized for separating heavy metals like Fe(III), Cr(III), Cu(II), Ni(II), Co(II), and Pb(II) by liquid membrane transport method. The effects of pH, ion carrier volume, stripping concentration, transport time, and metal ion concentration were investigated to obtain optimum conditions. Experimental results showed that optimum pH occurred at pH 4 for Fe(III) ions and pH 5 for others. Carrier volumes were optimum at 8.5 mL for Fe(III) and Pb(II) ions but 7.5 mL for others. The optimum concentrations of the stripping phase were 2 M for Fe(III) and Cu(II) ions, 1 M for Cr(III), Ni(II), Co(II) ions, and 0.5 M for Pb(II) ion. Transport times were optimum at 36 h for Fe(III) and Co(II) ions and 48 h for others. The optimum metal ion concentrations were 0.25 mM for Fe(III) and Cr(III) ions, while other ions were 0.1 mM. The response of PEEOA to Fe(III) ion was the best with selectivity order, Fe(III) &gt; Cr(III) &gt; Pb(II) &gt; Cu(II) &gt; Ni(II) &gt; Co(II). PEEOA also could separate Fe and Ni in a ferronickel sample whose transport percents were 8.87 and 0.92%, respectively. Hence, PEEOA is reasonably effective as an ions carrier for separating metal ions individually or ionic mixture and also in a ferronickel compound.

Impact of Verticutting on the Efficacy and Soil Activity of ALS-inhibiting Herbicides for Dallisgrass Control

Dallisgrass (Paspalum dilatatum Poir.) control with postemergence herbicides is inefficient and inconsistent from year to year. Control with acetolactate synthase (ALS)-inhibiting herbicides may be enhanced through root absorption, but herbicide movement through dense turfgrass canopies may be difficult. The objectives of this research were to evaluate the influence of verticutting on the postemergence control of dallisgrass and the presence of ALS-inhibiting herbicides within the soil profile. Long-term dallisgrass control [17 weeks after initial treatment (WAIT)] was enhanced in response to verticutting at one of two locations. This may be attributed to differences in turfgrass management (mowing height) before trial initiation that impacted dallisgrass carbohydrate content and herbicide absorption. However, dallisgrass control with certain herbicides was enhanced at the second location in response to verticutting at earlier rating dates. Thiencarbazone + foramsulfuron + halosulfuron (TFH) and trifloxysulfuron at 112 g·ha−1 a.i. and carrier volume of 1628 L·ha−1 (TRI High CV) following mowing + verticutting resulted in the greatest long-term control 17 WAIT at one of two trial locations, 86% and 85%, respectively. Greenhouse experiments confirmed that mowing + verticutting dallisgrass before treatment followed by irrigation led to an increase in herbicide presence within the soil profile, regardless of herbicide. Presence of TFH went from 6.4 to 8.2 mm, trifloxysulfuron at 28 g·ha−1 a.i. and carrier volume of 407 L·ha−1 went from 6.7 to 8.5 mm, and TRI High CV went from 8.6 to 11.8 mm.

Numerical simulation of fuel reactor for a methane-fueled chemical looping combustion using bubbling fluidized bed with internal particle circulation

Chemical-looping combustion (CLC) is recognized as a promising technique to efficiently and economically capture emitted carbon dioxide in common combustion processes. In this study, the bubbling fluidized bed (BFB) fuel reactor performance of the CLC system was examined through numerical simulation. The reduction reaction performance obtained from conventional BFB fuel reactor and BFB fuel reactor incorporated with internal particle circulation denoted as internal circulation bubbling fluidized bed reactor (ICBFB), were compared under the same fuel flow rate and operating conditions. By using CH4 as fuel and ilmenite as the oxygen carrier, it was found the reduction reaction can be enhanced by using the ICBFB fuel reactor due to particle circulation. The particle circulation increased the mixing and contact time between fuel and oxygen carrier that produced reduction reaction enhancement. Moreover, the simulation results indicated that higher reduction reaction performance can be achieved by higher reduction reaction temperature and initial oxygen carrier volume fraction.

Simulated herbicide spray retention on floating aquatic plants as affected by carrier volume and adjuvant type

AbstractFoliar delivery of herbicides is a common means for plant management in aquatic environments. Though this technique is decades old, little is known about vegetative spray retention relative to this application method. A more complete understanding of maximizing herbicide retention could lead to improved plant management while simultaneously decreasing pesticide load in aquatic environments. Therefore outdoor mesocosm experiments were conducted in 2020 to evaluate the effect of adjuvant type on foliar spray retention in waterhyacinth [Eichhornia crassipes (Mart.) Solms]. Additionally, the effect of carrier volume on spray retention in waterhyacinth, waterlettuce (Pistia stratiotes L.), and giant salvinia (Salvinia molesta D.S. Mitchell) was documented. Spray deposition did not differ among the nine adjuvants tested; however, spray retention was reduced 6% to 11% when an adjuvant was excluded from the spray solution. The effect of carrier volume on spray retention in waterhyacinth, waterlettuce, and giant salvinia was also investigated. Decreases in spray retention were most sensitive to increased carrier volume in waterhyacinth, followed by giant salvinia and waterlettuce. Among species, spray retention potential, as determined by intercept estimates, was greatest in waterlettuce and giant salvinia regardless of carrier volume. Asymptotes estimates for waterhyacinth, waterlettuce, and giant salvinia were 33%, 46%, and 79% spray retention, respectively. In other words, spray retention was the lowest and remained relatively constant at these values for the high carrier volumes tested (935 and 1,870 L ha−1), which were likely due to the presence of pubescence on leaves and flatter leaf architecture represented by waterlettuce and giant salvinia compared to the glabrous vertical leaves of waterhyacinth. Future research will evaluate these concepts under field conditions.

Optimization of the photocatalyst coating and operating conditions in an intimately coupled photocatalysis and biodegradation reactor: Towards stable and efficient performance

Intimately coupled photocatalysis and biodegradation (ICPB) is an attractive novel technology for the mineralization and detoxification of persistent organics. Good photocatalytic performance is essential for an advanced ICPB operation, and the photocatalyst coating and illumination conditions are strong determining factors. In this work, response surface methodology (RSM) involving the central composite design (CCD) was employed to discover optimal operating conditions, by using tetracycline hydrochloride (TCH) as the model pollutant. Polyvinyl butyral (PVB) was employed to form an adhesion layer, enhancing P25 TiO2 activity and stability. We achieved the optimal coating conditions with a mixing time of 20 h, TiO2 dosage of 8 g/L, and PVB concentration of 0.5 wt.%. The optimum running conditions for an ICPB-reactor were found to be at a carrier volume ratio of 40% and light intensity of 6000 μw/cm2. These conditions were essential for the production of desired intermediates and functional microbial survival. At the optimized parameters ranges, ∼98% TCH removal and ∼40% mineralization was achieved, and the inhibition on Q67 illuminance was only 30.32%. This is the first work on optimizing the fabrication and operation of ICPB, which is meaningful for the application of ICPB in practical engineering.

On-Farm Evaluation of Nozzle Types for Peanut Pest Management Using Commercial Sprayers

ABSTRACT Growers have rapidly adopted auxin-resistant cotton and soybean technologies. In Georgia, growers who plant auxin-resistant cotton/soybean are required to utilize nozzles that produce larger (coarser) droplets when spraying auxin herbicides to minimize potential off-target movement of pesticides. Consequently, these nozzles are also used in peanut (an important rotational crop with cotton) since changing nozzles between crops is uncommon for growers. However, larger droplets can result in reduced spray coverage which may lead to less effective pest control. Therefore, seven on-farm trials were conducted in commercial peanut fields using commercial sprayers from 2018 to 2020 across four different locations in Georgia to compare the spray performance of air-induction (AI) nozzles that produce very coarse to ultra coarse droplets (VMD50 ≥ 404 microns) with non-AI (conventional flat fan) nozzles that produce medium to coarse droplets (403≥VMD50≥236 microns) for pest management in peanuts. For each trial, test treatments were implemented in large replicated strips where each strip represented a nozzle type. For nozzle comparison, XR and XRC represented non-AI nozzles while TADF, TDXL, TTI, and TTI60 represented the commonly used AI nozzles in these trials. Spray deposition data for each nozzle along with disease ratings, weed and insect control ratings were collected in all on-farm trials. Peanut yield was collected at harvest. Results indicated that the AI nozzles produced larger droplets than the non-AI nozzles in all nozzle tests; however, the spray coverage varied among the nozzle types. Nozzle type did not influence pest (weed, disease and insect) control, or peanut yield (p&amp;gt;0.10) in any of the on-farm trials. These results suggested that peanut growers can utilize these coarser droplet nozzles for pest management in fields with low to average pest pressure during the season. Future research on nozzle evaluation needs to investigate the influence of droplet size, carrier volume, and pressure on coverage and canopy penetration.

Tomato tolerance to preemergence herbicides in plasticulture using narrow bands and precision technology

Preemergence (PRE) herbicides are broadcast-applied over the entire top of raised beds prior to plastic mulch installation. Following mulch installation, broadleaves and grasses only emerge from the planting holes. For this reason, the majority of PRE herbicides that are broadcast-applied underneath the plastic mulch are unnecessary for weed control. To reduce off-target herbicide application, we evaluated (1) tomato tolerance to herbicides applied in narrow bands over the planting holes at 2 weeks after transplant (WATP), and (2) tomato tolerance to herbicides that were precisely applied to individual planting holes immediately prior to transplant using a precision herbicide applicator that was previously developed at the University of Florida. Halosulfuron, metribuzin, pendimethalin, and S-metolachlor applied in narrow bands over the planting holes at 2 WATP did not significantly injure tomato, stunt growth, nor reduce yield. However, significant tomato injury (7%) was observed when fomesafen was applied in narrow bands over the planting holes where tomato plants have been transplanted for 2 weeks. Precision application of fomesafen, metribuzin, oxyfluorfen, and S-metolachlor in a carrier volume of 187, 374, or 561 L ha−1 using the precision hole-punch sprayer to the individual planting holes prior to transplant caused minimal early-season tomato injury (≤4%) and did not significantly stunt tomato plant growth or reduce yield. Overall, results demonstrated a safe and effective way to reduce off-target herbicide application in plastic-mulched tomato by applying herbicides in bands over the planting holes after transplant or precisely applying herbicides to individual planting holes prior to transplant using a precision hole-punch applicator.