Spray Mixture Research Articles

Reduced Foliar Disease and Increased Yield of Pumpkin Regardless of Management Approach or Fungicide Combinations

Small- and large-scale farmers must often decide when to begin application of fungicides, either before the onset of disease as a preventative treatment or after disease becomes evident in the field. Growers also must decide about products that claim to enhance fungicide efficacy when added to the spray mixture. A study was conducted during the summer of 2002 to investigate control of foliar diseases of vine crops (Cucurbita spp.) with low-input (LI) or high-input (HI) management approaches and six fungicide/spray combinations at four locations in southeastern United States. Fungicide applications began for LI when leaf disease first became evident and for HI about 20 days after seeding. Both approaches continued applications at 7- to 10-day intervals until harvest. Spray treatments consisted of a water-only control or one of six combinations of azoxystrobin/chlorothalonil alone or in combination with potassium bicarbonate, foliar phosphite (0N–12.2P–21.6K), or foliar nitrogen (25N–0P–0K). Azoxystrobin was applied in rotation with chlorothalonil for all treatments except the control. Seeds of ‘Lil’ Goblin’ pumpkin (Cucurbita pepo) were planted July to August and fruit harvested October to November, depending on location. Plants were rated twice for powdery mildew (Sphaerotheca fuliginea and Erysiphe cichoracearum) and downy mildew (Pseudoperonospora cubensis). HI did not significantly increase yield compared with LI. All fungicide treatments significantly increased yield and reduced foliar diseases compared with the water-only control. The simplest of treatments, the azoxystrobin/chlorothalonil rotation without any other chemicals, can be recommended for general use where strobilurin resistance has not been documented.

Influence of agricultural adjuvants on droplet spectra

The formation of a spray is the result of interaction between the nozzle type and the spray liquid. When adjuvants lower the surface tension, a shift to a finer spray quality might be expected. Increases in viscosity might cause coarser sprays. The spray pressure, nozzle type and spray liquid determine spray performance. Adjuvants that cause droplets of oil in the spray mixture, for example crop oils, petroleum oils and even some water-insoluble emulsifiers and surfactants, may unexpectedly increase the spray droplet size. In cases where a finer spray is obtained, the volume fraction of drops smaller than 100 microm diameter, V(100), is expected to increase, but for some adjuvants a decrease in V(100) is observed. Finally, spray droplets may also differ when the concentration of the applied adjuvants changes. An overview based on reports in the literature is given of the effects of different classes of adjuvants used for agricultural cropping on spray droplet spectra. The effects of these adjuvants on spray formation depend on the type of nozzle in combination with the applied pressure.

Biological Monitoring of Pesticide Exposures among Applicators and Their Children in Nicaragua

Exposures were assessed for seven small-scale farmers using chlorpyrifos on corn and ten banana plantation employees applying diazinon, and for one child of each worker. Metabolites (TCPYand IMPY) were measured in urine before and after applications. TCPY concentrations peaked at 27 and 8.5 hours post-application for applicators and children, respectively (geometric means, 26 and 3.0 microg/L). Proximity to spraying and spray mixture preparation in homes were important exposure factors. IMPY concentrations differed substantially across workers at two plantations (geometric means, 1.3 and 168 mirog/L); however, their children had little or no diazinon exposure. These workers and children were also exposed to chlorpyrifos, most likely through contact with chlorpyrifos-impregnated bags used in banana production. Several recommendations are offered: (1) monitor children's activities during applications; (2) do not store or prepare pesticides in homes; (3) institute sound occupational hygiene practices at banana plantations; (4) dispose of plastic insecticide bags properly at the worksite.

Air Gas Dynamic Spraying of Powder Mixtures: Theory and Application

The radial injection gas dynamic spray (RIGDS) technology of powder coatings deposition was considered for this work. A coating was created by injecting powders with variable compositions into a supersonic air jet and depositing powder on the substrate. This study describes the preliminary analysis of an air gas dynamic spray method realized by a portable RIGDS apparatus with a radial injection of powder. Attention was given to shock compaction processes during the coating structure formation and examples of powder mixtures utilization in RIGDS. It was shown that the operational parameters of supersonic powder-gas jet have a significant influence on the coating's microstructure, thus defining the high performance of the coating. Compaction and bonding of particles were analyzed.

Blue TiO $$_{2 -x}$$ /SiO2 nanoparticles by laser pyrolysis

Composite TiSiOC nanoparticles with Ti/Si ratio varying in a very large range were prepared by laser pyrolysis of a gas–spray mixture of silane and titanium tetra-isopropoxide. The as-formed nanoparticle batches exhibit intense blue colours, varying from dark to light blue while the Ti/Si ratio increases. This blue colour is attributed to the formation of sub-stoichiometric TiO\(_{2-x}\)compounds induced by the presence of reducing agents such as silicon-based radicals and carbon atoms in the reaction medium. The blue colour of the powders is stable for several months at room temperature in normal atmospheric conditions. Elemental analysis, specific surface area and pycnometry measurements, as well as Photon Correlation Spectroscopy allow determining the chemical composition and size of the as-synthesized nanoparticles as a function of the Ti/Si ratio. X-ray diffraction, transmission electron microscopy and IR spectroscopy have been used to analyse their chemical organisation, nanostructure and morphology. Mean grain size is found around 20 nm. The nanoparticles exhibit a core-shell structure TiO\(_{2-x}\)/SiO2, with a core made of titania, surrounded by an amorphous shell, mainly of silica. Crystallites of anatase are present in the core with size increasing with the Ti/Si ratio. Annealing under air at 800°C induces the removal of carbon and the crystallisation of the powders with light beige to white colours.

Wind Tunnel Evaluation of Drift Reduction Potential and Spray Characteristics with Drift Retardants at High Operating Pressure

Abstract Although considerable research has been done on effectiveness of drift retardants for many years, answers to some questions are still unclear to applicators. Laboratory tests were conducted to evaluate drift potentials associated with off-target ground and airborne spray deposits discharged with a hollow cone nozzle spraying three different drift retardants at a high operating pressure and various wind velocities in a wind tunnel. Droplet sizes and spray widths were also determined with a laser imaging system and a portable spray patternator. At 1655 kPa pressure and 4.65 L/m flow rate, the volume median diameters of droplets from the hollow cone nozzle discharging spray mixtures containing water only, polyvinyl polymer, nonionic colloidal polymer and polyacrylamide polymer drift retardants were 201, 222, 239, and 210 μm, respectively. The major spray pattern width was not changed after drift retardants were added into the spray carrier. For the wind velocity from 1 to 5 m/s in the wind tunnel, the polyacrylamide drift retardant produced the highest airborne deposit among the three drift retardants, followed by polyvinyl, and then nonionic colloidal. Also, the polyacrylamide drift retardant produced the highest ground drift potential, followed by nonionic colloidal and then polyvinyl. According to the results from this laboratory study, both nonionic colloidal and polyvinyl polymer drift retardants reduced the drift potential compared to the spray carrier containing water only.

Synthesis and characterization of PAni–SiO2 and PTh–SiO2 nanocomposites' thin films by plasma polymerization

In the present work, we explore the possibility to deposit polyaniline–silicon dioxide (PAni–SiO2) and polythiophene–silicon dioxide (PTh–SiO2) nanocomposites through a plasma polymerization route. The films were generated by spraying of mixtures of nano-sized silica particles dispersed in the liquid monomer into a plasma stream of the DC-plasma discharge reactor. The silica in the resulted polymer matrix changes the conduction mechanisms varying from ohmic to ballistic and traps inducing the space charged limited currents (SCLC). The silica modifies the morphology and composition of the deposited films.

FOLIAR DEPOSITION AND OFF-TARGET LOSS WITH DIFFERENT SPRAY TECHNIQUES IN NURSERY APPLICATIONS

Information is lacking on spray techniques to improve deposit uniformity within nursery canopies and reduceoff-target loss on the ground and via spray drift from the treated area. Spray deposits at various elevations within crabappletrees and on the ground were investigated with an air blast sprayer equipped with conventional hollow-cone nozzles,air-induction nozzles, and conventional hollow-cone nozzles with a drift retardant in a commercial nursery field. Airbornedeposits at three elevations on sampling towers and on the ground at several distances from the sprayer were also investigatedwith the three spray treatments in an open area without trees. To compare field test results, wind tunnel experiments wereconducted to assess spray deposits on the floor beyond 0.4 m downwind distance from the nozzles and airborne deposits at2.1 m downwind from the spray discharge point with the three spray techniques without air assist. Droplet size distributionsacross spray patterns without air assist were measured with a laser particle/droplet image analysis system. In general, therewas no significant difference for deposits within nursery tree canopies and on the ground with three different spray techniques.At the 700 L/ha application rate, which was 360 L/ha lower than the rate typically used in nursery application, the treecanopies received over 4 to 14.5 times as much spray deposit as actually needed from all treatments, and a large portion ofspray volume deposited on the ground. Compared with conventional hollow-cone nozzles, drift reduction from air-inductionnozzles or the spray mixture with drift retardant treatment was significant in wind tunnel tests but was not significant in fieldtests.

Comparison of String and Ribbon Samplers in Orchard Spray Applications

The main objective of this study was to establish the relationship between spray deposition on ribbon and string samplers in field applications. The experiment involved five commonly used citrus air-carrier sprayers, which included both conventional and tower configurations, equipped with axial- or cross-flow fans and hydraulic nozzles or rotary atomizers. A sampling structure, consisting of vertical and horizontal lines of polyester string and cotton ribbon, was constructed in a citrus grove. Spray mixtures, containing a fluorescent tracer, were applied at different volume rates and ground speeds (nine treatments) on a 30 m course between two tree rows. Shortly after spraying each replication, the lines were collected in pieces. In the laboratory, the amount of deposit was determined by fluorometry. Weather data recorded during the applications were used as co-variables in the analysis of variance. Each treatment was replicated 3 to 5 times. The results showed a significant difference between capture efficiencies of the two target types. In all sample locations, the amount of spray deposit on the string was higher than that captured on cotton ribbon. Overall, the mean and standard deviation of the string/ribbon deposit ratios were 2.3 and 0.7, respectively.

4729 多噴孔ディーゼル噴霧の混合気形成および着火・燃焼過程の研究(S55-1 エンジン現象解析-基礎計測と数値計算-(1),S55 エンジン現象解析-基礎計測と数値計算-)

This study tried to investigate the evaporation and ignition of a diesel spray using a rapid compression machine focusing on mixture formation of fuel and air. Swirl velocity and nozzle hole-number were changed in this report. Photography of spray development using high-speed digital video camera and measurement of pressure history showed relationship between air motion and spray evaporation during ignition delay period. In the case of low swirl, wall impingement of spray and rich mixture formation near injector outlet restrain spray evaporation. In the case of high swirl, spray interference for a large hole-number injector strongly affects spray evaporation.

Movement of Diuron and Hexazinone in Clay Soil and Infiltrated Pond Water

Pre-emergence herbicide residues were detected in domestic wells sampled near Tracy, CA. This study sought to determine the source of contamination by comparing soil distribution of diuron [N'-(3,4-dichlorophenyl)-N,N-dimethylurea] and hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] in an agricultural field where the soil was a cracking clay to infiltration of residues in water captured by an adjacent holding pond. Diuron and hexazinone were applied in December to a 3-yr-old alfalfa (Medicago sativa L.) crop. Water content of soil taken after major rainfall but before irrigation at 106 d after application was elevated at the lowest depth sampled centered at 953 mm, indicating water was available for percolation. Herbicide residues (reporting limit 8 microg kg(-1)) were confined above the 152 mm soil depth, even after subsequent application of two border-check surface irrigations. The pattern of distribution and concentration of residues in the soil were similar to results obtained from the LEACHM model, suggesting that macropore flow was limited to a shallow depth of soil. Herbicide residues were measured in runoff water at the first irrigation at 20 microg L(-1) for diuron and 1 microg L(-1) for hexazinone. Runoff water captured in the pond rapidly infiltrated into the subsurface soil, causing a concomitant rise in ground water elevation near the pond. Herbicide residues were also detected in the sampled ground water. We concluded that the pond was the predominant source for movement to ground water. Since addition of a surfactant to the spray mixture did not reduce concentrations in runoff water, mitigation methods will focus on minimizing infiltration of water from the pond.

Nozzle Formulation Interactions: Consequences for Spray Droplet Adhesion to Plant Surfaces

Abstract Tests were conducted with a widely used herbicide (glyphosate) that is available in a range of formulations and a selection of commonly used nozzle types [XR TeeJet, extended range flat spray tip (XR), Turbo TeeJet, wide angle flat spray tip (TT), AI TeeJet, Air Induction spray tip (AI)] and determined the rebound characteristics of each combination using a difficult-to-wet foliar crop target (cabbage), an easy-to-wet hairy weed (velvetleaf), and a difficult-to-wet weed (lambsquarters). The rebound was determined under standard spraying conditions in a track room using a “bounce chamber” constructed at The Laboratory for Pest Control Application Technology (LPCAT). The amount of spray liquid retained and reflected from the leaf surfaces was determined by weight. The data showed that there were no significant differences between the nozzles, but that formulation differences did occur and were a reflection of surfactant level in the spray mixture. There was a significant formulation X leaf interaction and leaf X nozzle interaction, but not a formulation X nozzle interaction.

Combination of Fan Ventilation System and Spraying of Oil-Water Mixture on the Levels of Dust and Gases in Caged Layer Facilities in Eastern Turkey

Kocaman, B., Yaganoglu, A.V. and Yanar, M. 2005. Combination of fan ventilation system and spraying of oil-water mixture on the levels of dust and gases in caged layer facilities in Eastern Turkey. J. Appl. Anim. Res., 27: 109–111. To reduce harmful gases such as CO2, NH3 and H2S and dust in caged layer houses in Eastern Turkey, spraying of sunflower oil-water mixture and fan Uentilation were investigated. It is demonstrated that these treatments together may improve air of the caged layer houses.

Increasing the Biological Activity of Weak Acid Herbicides by Increasing and Decreasing the pH of the Spray Mixture

Abstract The pH of the spray mixture controls the solubility and ionic state of weak acid herbicides and thus influences their uptake and biological activity. When the pH of the spray water is below the pKa of the herbicide, increasing pH can increase solubility and improve activity when herbicide solubility limits uptake. However, raising the pH above the pKa makes the weak acid anionic and thus may make it more difficult to penetrate into the lipophilic cuticle and the negatively charged membrane and cell wall. Decreasing the pH below the pKa converts the weak acid into a neutral or unionized form and thus makes it easier to penetrate these lipophilic and negatively charged barriers. pH also influences other herbicide properties including chemical stability, volatility, and chemical compatibility. Thus, manufacturers need to balance a number of properties when they adjust the pH of their adjuvant and herbicide formulations. These studies show significant differences in the biological activity of several herbicides when the pH is increased and decreased with a range of surfactant types. These results support the concept that the physicochemical properties of the herbicide and adjuvant should be matched for optimum activity.

Evaluating Drift Control Agents to Reduce Short Distance Movement and Effect on Herbicide Performance1

Spray drift to unintended areas is more of a concern as applications of nonselective herbicides associated with herbicide-resistant crops and the proximity of residential land to agricultural land increase. This research evaluated the benefit of three commercial drift control agents for effectiveness in reducing drift in 19 to 24 km/h wind and their potential effect on weed control. The drift control agents were added to a spray mixture of glyphosate at 0.8 kg ae/ha applied in 140 L/ ha and applied with either flat-fan or flood nozzles. None of the drift control agents reduced drift compared with the spray mixture without drift control agent over a distance of 6 m, as measured by water-sensitive cards or grain sorghum bioassay, regardless of nozzle type used. In a separate study, drift control agents did not reduce the weed control of glyphosate or acifluorfen. Nomenclature: Acifluorfen; glyphosate; grain sorghum, Sorghum bicolor (L.) Moench. Additional index words: Adjuvants, bioassay, crop injury, flat-...

Maximizing Performance of Plant Growth Regulators by Improving Spray Application

The importance of spray application and the role of spray additives are reviewed in reference to increasing the effectiveness of plant growth regulators (PGR). The spray application process is composed of a number of interrelated components, from formulation of the active ingredient into a sprayable, bioactive solution (emulsion/suspension), to atomization, delivery, retention, and penetration into the plant tissue. Each of these events is critical to performance of the PGR. Also, each can be affected by spray additives, particularly adjuvants, which may be incorporated in the formulation of the active ingredient or added to the spray mixture. The role of the individual components and effects of spray adjuvants, particularly surfactants and fertilizer adjuvants, on the component processes are discussed.

AN ELECTRONIC SENSOR TO CHARACTERIZE TRANSIENT RESPONSE OF NOZZLE INJECTION FOR PESTICIDE SPRAYING

An electronic sensor was developed to characterize the transient response of a two-fluid mixture spray emissioncreated by injecting a pulse of concentrated solution into a carrier fluid within a spray nozzle. The test situation simulatedan intermittent, at-nozzle chemical injection system for spraying of distinct targets. The principle of sensor operation wasmeasurement of the electrical resistance of an element of the emitted fluid created by injecting a concentrated sodium chloridesolution into a water carrier. The sensor was initially calibrated with steady-state flow of carrier liquid over a range of 10to 1500 ppm NaCl concentration. The high temporal response of the sensor provided measurement of the transientconcentration of injected NaCl solution during brief (10 to 100 ms) injection events into the steady-state flow of the carrierliquid. The accuracy and transient response were quantified by comparing the volume of injected salt solution as determinedby integrating the instantaneous concentration over the measured event with a direct volumetric measurement of the injectedvolume. Excellent agreement between volume measurements of injection and predicted injection volumes was found,validating sensor use for injection studies. The relatively simple sensor design provides the accuracy and high-frequencyresponse necessary for at-nozzle injection studies.

Broadleaf Weed Control and Potato Crop Safety with Postemergence Rimsulfuron, Metribuzin, and Adjuvant Combinations

The effects of postemergence rimsulfuron, metribuzin, and adjuvant combinations on potato crop safety and weed control were evaluated in field studies conducted at the University of Idaho Aberdeen Research and Extension Center in 1999 and 2000. Rimsulfuron at 26 g ai/ha plus metribuzin at 0, 140, or 280 g ai/ha was combined with nonionic surfactant (NIS), crop oil concentrate (COC), or methylated seed oil (MSO) in a 3 by 3 factorial with two controls. Under cool, cloudy conditions in 1999, initial ‘Russet Burbank’ potato injury was greater when metribuzin was included in the tank mixture than when rimsulfuron was applied alone, regardless of adjuvant. Under warmer conditions in 2000, however, adding MSO or COC to the tank mixture caused more injury than adding NIS. Rimsulfuron did not provide acceptable season-long common lambsquarters control in 1999 (76%) or in 2000 (88%), regardless of adjuvant. Rimsulfuron combined with metribuzin at 140 or 280 g/ha provided ≥95% common lambsquarters control both years, regardless of adjuvant. Among adjuvants, using MSO (1999 and 2000) or COC (2000) in the spray mixture improved common lambsquarters control compared with using NIS. Tuber yield and quality were not reduced as a result of metribuzin rate or adjuvant treatments either year compared with the weed-free control.

Spray Penetration into Peanut Canopies with Hydraulic Nozzle Tips

The spray penetration into peanut canopies with single- and twin-row planting systems at three growth stages was investigated with four different types of hydraulic nozzle tips (flat fan, hollow cone, twin jet and air induction). The nozzles were operated at 276 kPa pressure, 6·4 km h −1 travel speed, and 0·5 m above the top of canopies. The canopy leaf area index (LAI) and height were measured for each test and correlated with spray deposits at the bottom and middle of peanut canopies. Spray deposits at the top, middle and bottom of canopies were determined with a spray mixture containing water and a fluorescent tracer. The concentration of spray samples were corrected with the calibration of the photo degradation of the tracer exposed to direct sunlight, under artificial shade and in a dark room. Plants with single- and twin-row planting systems received significantly different spray deposits within peanut canopies. For all four nozzles during the growth season, the spray deposits decreased dramatically from the top to the bottom of canopies, and also tended to linearly decrease as LAI increased. Compared to the flat fan nozzle at the bottom of canopies at 75 days after planting, the air induction nozzle produced 2·6 times higher spray deposits for single-row plants and 1·6 times higher spray deposits for twin-row plants. During the three growth stages, the air induction nozzle produced the highest mean spray deposit at the bottom of canopies, followed by the twin jet and then hollow cone nozzles. The conventional flat fan nozzle had the lowest spray penetration performance among the four types of nozzles.

Liquid Sheet Break-up of High-Pressure Swirl Injector for DISI Engine(Spray Technologies, Atomization)

Experimental investigations of fuel breakup very close to nozzle of practical high-pressure swirl injector, which is used in direct injection spark ignition (DISI) engine, were carried out. In DISI engines, fuel is directly injected into cylinder therefore the spray characteristics and mixture formation are of primary importance. Many experimental investigations using several measurement techniques like laser sheet method with high-speed camera, LIF or PDA have been carried out for better understandings of spray and combustion characteristics. However, experimental investigations of atomization process were restricted due to very high-speed and very small region phenomena. Although scale-up models have been used to study the primary spray structure, it is impossible to match Reynolds, Weber, and cavitation numbers and time scales in practical high-pressure swirl injector. Microscopic investigation of primary spray structure of practical swirl injector is needed. On the other hand, numerical simulations have been conducted for better understanding of spray formation process. These researches indicated qualitatively good agreement, but the initial conditions, such as liquid sheet thickness and break-up length, were not accurately since break-up process of the liquid sheet from swirl injector has not been examined. In numerical simulation of spray behavior, a sub-model for atomization phenomena is very important. Therefore the primary atomization process and the break-up process of liquid sheet play an important role. In this research, visualizations of primary spray formation process were demonstrated using a high-speed video camera (maximum speed: Imfps) with a long-distance microscope. Initial state and development of the spray were discussed under the different ambient (back) pressure condition. During the injection period, the length and thickness of the liquid sheet, which is produced from the nozzle exit, were measured using Ar-ion laser sheet and high-speed camera. Moreover, fluctuations of the length and thickness of liquid sheet were discussed. Three main conclusions were drawn from this study. (1) It has been shown that the liquid fuel column without swirl motion was injected as a compact jet at the beginning of the injection. During the injection period, the spray indicates the quasi-steady state mode. (2) Liquid film sheet has a ligament structure. Using Ar-ion laser sheet and high-speed camera, length and thickness of the liquid sheet can be measured. (3) Surface waves of liquid sheet can be recognized. Higher ambient (back) pressure makes shorter wavelength of surface waves of liquid sheet of swirl injector.