Spray Line Research Articles

Effects of Magnetized, Chelated Iron Foliage Treatments, and Metal Halide Lamps on Plant Water Structure, Water Vapor Dynamics, and Resilience for Legumes under Water Stress

A greenhouse study was conducted to determine the effects of foliar applications of magnetized, chelated liquid iron fertilizer for increasing the drought tolerance of two legumes. The study objectives were to determine the drought tolerance effects of four treatments on foliar gas exchange, soil moisture, and plant growth for soybean (Glycine max) and velvet bean (Mucuna pruriens) plants. The plant treatments included applications with chelated liquid iron fertilizer (2.5 and 5%) with a conventional boom sprayer, with and without magnets in the spray lines, and metal halide lamps. Three gas exchange measurements were collected before applying the foliage treatments and after two water stress treatments. A foliage and metal halide lamp treatment deactivated or unlinked nine interconnected gas exchange parameters that are correlated with plant defense activities during water stress conditions. The deactivation of interconnected regulatory gas exchange functions improved metabolic efficiency, reduced stress levels, and boosted plant resilience to abiotic stressors. Also, the study findings suggest that the study treatments maintained or increased the level of biologically structured water in plant tissues and vascular systems.

EVALUATION OF THREE BATTERY- POWERED BACKPACK SPRAYERS TO APPLY ADULTICIDES AGANIST AEDES AEGYPTI

Backpack mist sprayers have been used for control of adult mosquitoes on limited small scales. A study was conducted to evaluate three battery powered backpack sprayers to assess their suitability to apply adulticides. The three sprayers are the Field King 190515, the Ryobi One+, and the Tornado (model Spray Mate). The Field King operated at 276 kPa, the Ryobi One+ at 414 kPa, and the Tornado at 414kPa (option at 276 or 414 kPa) were used for this study. Due to higher flow rates of these sprayers compared to ULV sprayers, Aqualuer™ 20-20 was used as an adulticide by diluting with water. To achieve application rates of 9, 37, 74, and 148 mL/ha for different sprayers at their flow rates, the formulation was diluted 26 to 1,209 times. All dilutions were replicated three times and one application rate of all sprayers was tested in a day. Adult female Aedes aegypti mosquitoes at 25 /cage were used for the experiment. Caged mosquitoes were placed on the poles before spray and removed after the spray ended. Mortality was recorded at 24 -h after treatment. The Tornado backpack sprayer provided the highest mortality, better than or similar to Ryobi One+ and Field King provided the least mortality. The sprayers were effective up to 3.0 m from the spray line. By increasing application rate from 9 to 74 mL/ha, mortality increased but did not increase as the rate went from 74 to 148 mL/ha. Application with the Tornado at 74 mL/ha was the best option for short distance control.

EVALUATION OF THERMAL FOGGER FOR EFFECTIVENESS OF LARVICIDE-ADULTICIDE MIXTURE AGAINST AEDES AEGYPTI

A hand-held thermal fogger was evaluated to spray a mixture of adulticide (Aqualuer 20-20® containing permethrin and piperonyl butoxide) and a biological larvicide (VectoBac®12AS, containing Bacillus thuringiensis subspecies israelensis). Adulticide was applied at maximum label rate of 37 mL/ha while larvicide rates were 0.58, 1.76, 2.64, and 3.50 L/ha (Maximum label rate 2.34 L/ha). Two rows, 7.6 m apart, of bioassay cages containing susceptible 25, 5-7 days old female Aedes aegypti were used to assess effectiveness of the adulticide. Along with each cage were two 473 mL empty plastic cups at 0 and 1.3 m above ground to collect the larvicide. Two control cages and two empty cups were placed upwind in the field for five minutes and removed before the spray. The study was conducted in the evening with five separated replications of a rate. The exposed cages and cups were retrieved from the field and brought back to the laboratory for further observations and tests to determine mortality at 24 and 48 h, respectively. All the adults in all treatment cages and all tests died within 24 h of the spray application. In the lab, larval mortality was assessed by introducing Ae. aegypti larvae, where mortality decreased with increasing distance from the spray line and increased with increasing application rate. The larval mortality at all distances was strongly correlated with application rate (R2 = 0.98). The highest rate used produced 64 -95% larval mortality at all distances. The results indicate that Aqualuer 20-20 and VectoBac 12AS can be applied simultaneously as a mixture achieving complete adult control and considerable larval control.

Field Evaluation of Fyfanon Ew Against Aedes Aegypti: A Low Odor Ultra-Low Volume Formulation of Malathion.

A low odor formulation of ultra-low volume (ULV) malathion (Fyfanon EW®) mosquito adulticide was evaluated in the field for its efficacy using caged female Aedes aegypti. Cages were placed in three rows, 30 m apart at 30, 60, and 90 m from the spray line. The product was applied at the manufacturer's suggested operational rate of 0.28 liter/min (9.5 fl oz/min) and at the maximum label rate of 0.37 liter/min (12.6 fl oz/min) with a Guardian 190ES truck mounted ULV sprayer. At 1 h post-treatment for the manufacturer's suggested operational rate, adult mortality ranged from 85% at 30 m to 46% at 90 m (overall average 65.5%). At 24 h post-treatment, mortality was significantly greater at each distance with complete control of caged mosquitoes at 30 m and >95% at 90 m. Overall, 24-h average mortality at this rate was 96.8%. At the maximum label rate, mosquito mortality at 1 h was considerably greater at all distances and ranged from about 89% to 75% with an overall average of 84.3%. At 24 h post-treatment, complete mortality was recorded at all transect distances at this higher rate. In conclusion, our results showed that at 24 h, Fyfanon EW® was considered very effective when applied by ULV truck mounted ground equipment for area-wide control of mosquitoes.

The effect of spray nozzles failure on SO2 removal efficiency

ABSTRACT This study was carried out on an absorber in the body of flue gas desulphurization system (FGD) of a coal-fired power plant. In this study, efficiency losses caused by the clogging or breaking of the spray nozzles were examined. These abovementioned problems of spray nozzles are the most common among the many factors affecting the sulfur retention efficiency. Although energy and exergy analysis is very common to optimize the system efficiency of FGD units, failure of spray nozzles in absorbers might be the main reason in terms of low FGD units efficiency and low SO2 removal rates. In this study, firstly locations of clogged or damaged nozzles are determined by examining a total of 240 nozzles (3 × 80). After the replacement of the broken spray nozzles, increase in the efficiency of A-B, B-C, A-C and A-B-C spray lines were observed as 9.14%, 3.77%, 10.56%, 9.72%, respectively. Depending on the washing zone of the nozzles, if one nozzle is damaged, it causes the efficiency to decrease between 0.24% and 0.36%.

EFFECT OF NOZZLE ORIENTATION ON DISPERSION OF TRUCK MOUNTED ULTRA LOW VOLUME SPRAY AT DIFFERENT HEIGHTS AND DISTANCES

A field evaluation study was conducted to understand the dispersion of spray from a truck-mounted ultra-low-volume (ULV) sprayer when released with the nozzle oriented at the conventional angle of 45° in addition to 22° and 0° with respect to ground surface. The study was conducted in an open grassy field at the Anastasia Mosquito Control District by applying Aqualuer™ 20-20 at the highest label application rate. Mortality of caged female Aedes aegypti was tested at 1.5, 3.0, 6.0, and 8.5 m heights at 0, 30, 60, and 90 m from the spray line. Spray trials were conducted during early morning hours and all test groups were replicated three times over different days. During these evaluations higher mortality was recorded from the 22° and 0° nozzle orientations up to 30 m from the spray line and at heights up to 3 m. The conventional nozzle orientation of 45° provided the greatest mortality 30 m from application source at heights of 6.0 and 8.5 m.

Persistence and distribution of dinotefuran in tree of heaven.

Spotted lanternfly (SLF) (Lycorma delicatula (White)), an invasive planthopper discovered in Pennsylvania, U.S.A. in 2014, feeds for approximately six months by sucking phloem sap from trunks and limbs of tree of heaven, Ailanthus altissima, along with several native trees and woody vines. Basal trunk sprays of dinotefuran, a systemic neonicotinoid insecticide, are commonly used to reduce SLF densities and spread. Information on dinotefuran persistence and within-tree distribution can help identify optimal timing of annual basal trunk sprays, facilitating efficient use of available resources. We applied dinotefuran to 20 uninfested A. altissima trees in early April then periodically sampled foliage to monitor insecticide residues. Foliar dinotefuran residues averaged (± SE) 7.8 ± 1.1 and 6.3 ± 1.2 in July and August, respectively, then dropped significantly to 2.6 ± 0.5 ppm in September. In a second study, 20A. altissima trees were similarly treated with dinotefuran basal trunk sprays in early June. Trees were felled to collect foliage and phloem from branches and the trunk in either mid-July or September. Foliar residues averaged 12.7 ± 1.3 and 14.6 ± 2.2 ppm in July and September, respectively. For trees felled in July, residues were detected in phloem collected from below the spray line on trunks of seven trees and above the spray line on three trees, averaging 8.6 ± 4.4 and 7.4 ± 2.9 ppm, respectively. In trees felled in September, phloem from below spray lines of seven trees averaged 3.7 ± 1.3 ppm but dinotefuran was not detected in phloem from above the spray line on any trees. Dinotefuran was not detected in phloem sampled from any branches in either July or September. Results suggest dinotefuran basal trunk sprays applied between late May and mid June should persist long enough to effectively control SLF late instars and adults.

Air-Pinch PWM Valve to Regulate Flow Rate of Hollow-Cone Nozzles for Variable-Rate Sprayers

Highlights Air-pinch PWM valve was investigated as an alternative to electric PWM valves to manipulate hollow-cone nozzles. Air-pinch and electric PWM valves performed comparable accuracy in flow rate modulations. Droplet sizes from hollow-cone nozzles with both PWM valves were comparable across DUCs ranging from 20% to 100%. Air-pinch PWM valve had great potential of use due to its capacity to isolate the internal parts of the valve from chemicals. Abstract. Electric pulse width modulation (PWM) solenoid valves are commonly used to regulate nozzle flow rates to achieve precision variable-rate spray applications. However, some pesticide formulations, such as wettable powders and adhesive additives, can potentially cause a malfunction such that the valve cannot completely shut off during flow rate modulation if spray lines are not cleaned thoroughly after spray applications. An air-pinch PWM valve was evaluated as a potential alternative to conventional PWM valves to modulate the flow rates of hollow-cone nozzles used on air-assisted orchard sprayers. With the air-pinch valve, spray mixtures only passed through a flexible tube to avoid chemicals directly contacting the moving components inside the valve chamber. The flow rate modulation was performed by pinching and releasing the tube back and forth with air-pilot PWM actions. Evaluations included the flow rate modulation capability along with droplet size distributions from three disc-core hollow-cone nozzles coupled with the PWM pinch valve and compared with a conventional electric PWM valve. Both air-pinch and electric PWM valves performed comparably in the flow rate modulation accuracy and droplet size distribution for hollow-cone nozzles operated at 414 and 827 kPa pressures across the duty cycles (DUCs) ranging from 10% to 100%, except for the air-pinch valve that could not activate at 10% DUC. The flow rates of nozzles modulated with both PWM valves at all DUCs were 5.3% greater on average than the target flow rates, while the flow rates were similar at 90% and 100% DUCs. Droplet size classifications based on ASABE Standard S-572.3 were generally consistent across DUCs ranging from 20% to 100% for the same nozzle and pressure with the air-pinch PWM valve and from 10% to 100% with the conventional electric PWM valve. The consistency of droplet sizes across DUCs and accuracy of flow rate modulations demonstrated the potential advantage of using the air-pinch PWM solenoid valve as an alternative for precision variable-rate sprayers to accurately apply different chemicals. Keywords: Droplet size, Flow rate control, Pesticide, Pinch valve, Precision farming, Pulse width modulation.

New insight into air/spray boundary interaction for diesel and biodiesel fuels under different fuel temperatures

The liquid fuel breakup mechanism in spray injection with ambient air for diesel and biodiesel at different fuel temperatures is studied numerically. We find that biodiesel fuel type injection with low fuel temperature induces more air entrainment volume to the boundary of the spray than diesel fuel injection and higher fuel temperature. Meanwhile, the normalized parcel density for biodiesel is 12% larger than that of diesel and peaks at a shorter distance along the spray line from the injection point (42 vs. 46 mm). Biodiesel fuel demonstrates a maximum 0.395 mg/s of air mass flow while diesel max mass flow is 0.279 mg/s. As a result, the air entrainment volume of biodiesel to the moving spray area at 1.4 ms reaches 3723.98 mm3 while for diesel the amount is 3151.27 mm3. However, the absorbed y-direction air velocity into the spray core for diesel fuel is dominant. The results give new insights into air exchange to spray boundary in the near nozzle and spray tip area: towards the tip of spray the air pushout is remarkable. Higher fuel temperature leads to slightly lower air exchange flow and entrainment (5.2%), cone angle reduction from 300 to 325 K fuel temperature, and increased surface area:volume ratio for diesel.

Effects of Magnetized, Chelated Iron Foliage Treatments on Foliar Physiology, Plant Growth and Drought Tolerance for Two Legume Species

A greenhouse study was conducted to determine the effects of foliar applications of magnetized, chelated liquid iron fertilizer for increasing the drought tolerance of two legumes. Study objectives were to determine the drought tolerance effects of four treatments on foliar gas exchange, soil moisture, and plant growth for velvet bean (Mucuns pruriens) and soybean (Gylcine max) plants. The four foliage treatments included applications with chelated liquid iron fertilizer (2.5 and 5%) with a conventional boom sprayer, with and without magnets in the spray lines. Physiological measurements were collected before foliar treatments and again after a 24-day deficit irrigation schedule. Physicochemical water properties were measured for each of the foliar treatments. Photosynthesis rates were 5.98, 2.04 and 3.19 µmol/m2/s for the control, non-magnetized and magnetized fertilizer treatments (2.5%), respectively, after completing the deficit irrigation schedule. Instantaneous water use efficiency (IWUE) was 0.60, 0.28 and 1.02 for the control, non-magnetized and magnetized fertilizer treatments (2.5%), respectively, after completing the deficit irrigation schedule. Photosynthesis and IWUE increased 56 and 263% for the magnetized fertilizer treatment (2.5%) compared to the non-magnetized foliar treatment, when averaged across both legume species. Photosynthesis and IWUE increased as electrical conductivity increased and oxidation reduction potential (ORP) decreased in absolute terms. A single foliar application resulted in aberrant physiological responses that are contrary to very widely held plant defense theories involving abiotic stressors. The single application improved the photosynthesis and water use efficiency for water stressed legumes emphasizing the need to better understand the relationships between water quality, plant bioenergetics, and stress physiology. Improved drought tolerance in row crops such as dry beans and soybeans, with a single magnetized fertilizer application, would be cost effective and easily adapted into current cropping systems. Interactions among physicochemical water properties, bioenergetics, plant metabolism, and crop stress physiology need to be further investigated in order to improve the quality of irrigation water to enhance drought tolerance of field crops.

Ground Applications of Vectobac® WDG with A1 Super-Duty Mist Sprayer® and Micronair® AU5000 Atomizer for Suppression of Aedes aegypti Populations in the Florida Keys.

Since 2011, the Florida Keys Mosquito Control District (FKMCD) has used the WALS® application strategy with VectoBac® WDG containing Bacillus thuringiensis israelensis via helicopter in Key West for the control of Aedes aegypti larval populations. In 2018, FKMCD conducted a study to determine the effectiveness of using a trailer-mounted A1 Super Duty Mist Sprayer® (A1 Mist Sprayers) with a Micronair® AU5000 (Micron Group) atomizer to apply VectoBac WDG by ground at the rate of 0.5 lb/acre (0.56 kg/ha). Bioassay cups were placed in a residential area encompassing open, moderate, and heavy cover scenarios between 0 and 300 ft (0-91.44 m) perpendicular to the spray line. An application rate of 0.5 lbs/acre (0.56 kg/ha) was used. Bioassay cups were collected after application and returned to the laboratory where 100 ml of distilled water and 10 F1 generation Ae. aegypti larvae were added. Laval mortality was monitored at 2, 4, and 24 h. Three separate runs were completed during the summer of 2018. Average larval mortality at 24 h was >90%. The field trial demonstrated sufficient efficacy to introduce this method of larviciding into operational use.

EVALUATION OF A NEW TRUCK-MOUNTED ULV SPRAYING MACHINE WITH BACILLUS THURINGIENSIS VAR. ISRAELENSIS AGAINST LARVAL CULEX QUINQUEFASCIATUS

A field study about the effectiveness of a new truck-mounted ultra-low-volume (ULV) machine against larval Culex quinquefasciatus Say was conducted at Anastasia Mosquito Control District of St. Johns County, St. Augustine, FL, during the summer of 2017. Cx. quinquefasciatus larvae were treated using a ground application at different concentrations of Bti using a new truck-mounted ULV sprayer with a horizontal nozzle. Mortality of larvae was recorded after 24 h, and droplet sizes were measured. Overall, Bti sprayed by the new truck-mounted ULV spraying machine at a concentration of 2.625 mg/L resulted in the highest mortality of mosquito larvae. The results indicate that the Bti concentrations of 0.875 mg/L and 0.065 mg/L resulted in a significant difference in mean larval mortality between each distance from the spray line (P < 0.05), while the mortality by the other 3 concentrations (0.477 mg/L, 2.625 mg/L, and 5.25 mg/L) tested did not. The LC50 and LC90 of Bti against larvae were 0.261 mg/L (0.239~0.286) and 1.687 mg/L (1.481~1.922), respectively. The coverage (swath) of the spray by the new ULV machine showed that the Bti could be sprayed at least 33 meters away with a 20 meter width. Therefore, the new truck-mounted ULV spraying machine with liquid Bti could be used to treat a large area effectively and efficiently and as an additional tool for the control of mosquito larvae.

Development and Performance Evaluation of a Pneumatic Solid Set Canopy Delivery System for High-Density Apple Orchards

Abstract. Solid set canopy delivery systems (SSCDS) are fixed spray systems that consist of a network of permanently plumbed emitters in high-density tree-fruit orchard canopies. Most of the previously configured SSCDS worked on the principle of hydraulic spray delivery (HSD), which may not be suitable for large-scale installation due to the drop in operating pressure caused by frictional losses in the spray lines. Therefore, a pneumatic spray delivery (PSD) based SSCDS was developed in this study for potentially achieving uniform spray application at all locations along the spray lines. A reservoir subsystem was developed to contain a precisely metered amount of spray liquid. Once filled, compressed air pushed through the spray lines can pressurize the reservoir to help deliver uniform spray into the canopy through emitters. In this study, HSD and PSD systems of 91 m set length were installed in a high-density apple orchard. Both systems were evaluated for variations in operating pressure, spray output, and spray performance. Spray performance was quantified during the middle (BBCH 75) and late (BBCH 85) apple (cv. WA-38 on tall spindle architecture) crop growth stages. Deposition and coverage in three canopy zones and on both sides of leaves were evaluated using Mylar cards and water-sensitive papers (WSP) as samplers, respectively. The Mylar cards and WSP were respectively analyzed using fluorometry and image processing. Statistically similar operating pressure (p > 0.05) was observed for the HSD and PSD systems at 3 m (286.1 and 284.1 kPa, respectively), 33 m (268.4 and 270.5 kPa), 60 m (260.6 and 268.9 kPa), and 87 m (255.3 and 257.9 kPa) from the row inlet. Despite the operating pressure drop, the PSD system had uniform spray output along the 91 m spray line. Compared to the HSD system, about 4%, 3%, 5%, and 20% higher spray output was delivered with the PSD system at 3, 33, 60, and 87 m, respectively, along the spray line. Overall, the PSD system had significantly higher mean spray deposition (p < 0.01) compared to the HSD system during the middle (521 and 382 ng cm-2, respectively) and late (631 and 409 ng cm-2, respectively) growth stages. The PSD system also had numerically higher spray deposition compared to the HSD system for all the canopy zones and on either side of leaf surfaces. Spray coverage trends were similar to deposition; however, the differences were not significant. Overall, the PSD-based SSCDS shows potential for large-scale installation, with additional refinements, for uniform spray applications in high-density apple orchards. Keywords: Hydraulic spray delivery, Pneumatic spray delivery, Solid set canopy delivery system, Spray coverage, Spray deposition.

Technical Note: Model Physics and Collection Efficiency in Estimates of Pesticide Spray Drift Model Performance

HighlightsRecent large field programs are re-examined in the context of model development.Details of plant canopy wind fields are discussed.Collection efficiency of rotorods is discussed in detail, and the theory is used to re-examine field data.The approach used in the AGDISP model to simulate canopy wind fields is discussed in detail.Abstract. Recent field studies provided data to evaluate the performance of the aerial spray deposition algorithm in AGDISP. Those studies provided data for forest canopy settings that are either outside the stated domain of AGDISP or where assumptions in the model greatly impact the model performance. The two data sets were collected with the intention of providing input to drive model upgrades, but data limitations restricted that objective. Rather, this technical note shows that collection efficiency (CE) must always be considered (the model currently adjusts for CE only if the modeled output is canopy capture). One of the previous studies showed that the model substantially overpredicted droplet flux 65 m downwind of the spray line. Consideration of CE resolves some of this overprediction, but the model physics employed in AGDISP remain a substantial simplification of the complex flows that transport droplets in the atmospheric boundary layer near and in deep, three-dimensionally varying forest canopies. Keywords: Aerial application, AGDISP, Model, Spray drift.

Analysis of the crab waste spraying process

Introduction The companies dedicated to the spray of carbonate of calcium could realize in his substitute processes from the carapace spray of crab, generally in the process of milling, can identify several factors that contribute to the breach of the programmed work that are related with deficit in Supply volumes and unexpected failures in the operational phase of the micro spray of the crab carapace, which is why it is necessary to evaluate the impact that these factors can have and the causes that are causing deficiencies in the levels of programmed production. Objective. The present work focuses the analysis, diagnosis and proposals of solution of the problems that affects the "productivity" a spray line of the carapace of the crab. Materials and methods. The historical information regarding failures and deliveries of internal customer orders is reviewed. The analysis of the process is carried out identifying influential critical aspects in its poor performance. The cost of the losses associated with non-compliance is evaluated and investment plans for the implementation of the strategies related to supply policies and inventories of finished products and the systematization of remedial actions derived from the risk indicators of failures in the main subsystems are prepared. Results The financial analysis in this case allowed to determine an IRR of 20% and a positive NPV suggesting the feasibility of the proposals. Conclusions As a relevant finding, the cost of production per ton of crab powder was lower than the powder of the conventional product (calcium carbonate or limestone). Discussion both can be used as raw material in products used in the construction sector.

Application Efficacy of Vectobac WDG Against Larval Aedes aegypti Using Thermal Fog Technology.

The effectiveness of thermal fog application of Bacillus thuringiensis israelensis (Vectobac® WDG) against larval Aedes aegypti was evaluated in open and forest canopied environments in northeastern Florida, using a handheld IGEBA® TF34 thermal fogger (with water conversion kit). The product was applied at the maximum label rate of 1 kg/ha to linear transects, in each environment, containing empty 0.5-liter cups. After application, late-2nd to early-3rd instars of Ae. aegypti were added to each cup. Complete larval mortality occurred 48 h after treatment, 8 m away from the spray line in the open field while 63.4% larval mortality was achieved at this same distance in the forest canopy at 72 h posttreatment. Operational efficacy was then evaluated in an urban tropical environment in Key West, FL. In this study, empty plastic cups were placed in cryptic areas of a commercial lobster and crab trap yard. The 0.1-ha area was treated with Vectobac WDG at the maximum label rate using the same equipment. Aedes aegypti larval mortality from treated cups was >99% at 24 h posttreatment, whereas complete mortality was achieved at 48 h after application.

Spray Outputs from a Variable-Rate Sprayer Manipulated with PWM Solenoid Valves

Abstract. Pressure fluctuations from air-assisted orchard sprayers can cause nozzles to discharge inaccurate flow rates during variable-rate spray applications. Variations in total flow rate discharged from 40 nozzles, each coupled with a pulse-width-modulated (PWM) solenoid valve, were determined for a variable-rate air-assisted sprayer. Variables for the total flow rate measurements were number of active nozzles ranging from 1 to 40 and PWM duty cycle ranging from 10% to 100%. Experiments were conducted under conditions with and without operating pressure adjustments. Under the no-pressure-adjustment condition, the operating pressure in the spray line was not adjusted for compensation when either the number of active nozzles or PWM duty cycle was changed. Under the pressure-adjustment condition, the operating pressure was adjusted to retain at 242 kPa. The total flow rate increased as duty cycle and/or number of active nozzles increased under both pressure conditions. However, the operating pressure in the spray line dropped considerably as either the number of active nozzles or duty cycle increased under the no-pressure-adjustment condition, resulting in significant lower total flow rates compared to the pressure-adjustment condition. The differences in total flow rates between the two pressure conditions increased as duty cycle and number of active nozzles increased. To improve future intelligent sprayer accuracy, two-variable regression equations were established to predict and control total flow rates with different duty cycles and numbers of active nozzles operated simultaneously. Keywords: Flow control, Flow rate, Hydraulic nozzle, Pesticide, Precision sprayer.

Effect of Nozzle Orientation on Dispersion of Aqualuer 20-20 Sprayed by a Truck-Mounted Ultra-Low Volume Sprayer Against Caged Aedes aegypti.

Inconsistencies in efficacy of ultra-low volume (ULV) ground applications in the literature are linked to the lack of adjustments in sprayer parameters. To investigate the effect of nozzle orientation of a truck-mounted ULV sprayer on application efficacy, a study was conducted at St. Johns County Fairground, Elkton, FL, during the summer of 2014. The efficacy was assessed by mortality of caged adult Aedes aegypti, spray deposition, and droplet size spectrum up to 122 m from the spray line. Aqualuer 20-20 (20.6% permethrin active ingredient [AI] and 20% piperonyl butoxide [PBO]) was applied at the maximum label rate with the nozzle pointed 45° upward, horizontal (0°), or 30° downward. Mortality was recorded after 24 h, deposition was determined with fluorometry, and droplets were measured with DropVision. Overall, horizontal nozzle angle spraying Aqualuer 20-20 achieved the highest efficacy followed by a 30° downward angle, while a 45° angle showed the least efficacy in open field tests. The mortality data showed complete mortality from a 0° nozzle up to 122 m from the spray line except for 1 location at 122 m in 1 replication. The mortality from a 30° downward orientation was lower beyond 30 m from the spray line, while the mortality from a 45° upward orientation was low close to the spray line and beyond 30 m. Horizontal orientation had higher deposition than other orientations, but the differences were not significant. There was also no significant difference in droplet spectrum from all orientations.

Simulating the cooling effects of water spray systems in urban landscapes: A computational fluid dynamics study in Rotterdam, The Netherlands

Heat waves and the related heat stress can increase human morbidity and mortality, decrease human productivity and increase building energy consumption for cooling. There is a need for sustainable systems to reduce heat stress in urban areas. Evaporative cooling by water spray systems is increasingly used for this purpose. However, the evaluation of the cooling potential of such systems is difficult. To our knowledge, a systematic investigation of the cooling potential of such a system in an actual urban area has not yet been performed. This paper presents high-resolution Computational Fluid Dynamics (CFD) simulations based on the 3D unsteady Reynolds-Averaged Navier-Stokes equations to assess the cooling potential by a water spray system with 15 hollow-cone nozzles. The system is numerically implemented for a courtyard in the Bergpolder Zuid region of Rotterdam, the Netherlands and operated during the heat wave period of July 2006. The simulations are validated based on wind-tunnel measurements of an evaporative cooling process and satellite imagery data during the heat wave period. The Universal Thermal Climate Index (UTCI) is used to assess the heat stress reduction due to evaporative cooling. The results show that for given values of injected water flow rate (ṁw=9.0l/min) and height of the spray system (H=3m), a maximum temperature reduction and UTCI reduction of about 7 and 5°C are achieved at pedestrian height. In addition, a thermal comfort improvement from strong heat stress (without spray system) to moderate heat stress up to a distance of 5m from the spray line is obtained.

Truck-Mounted Area-Wide Application of Pyriproxyfen Targeting Aedes aegypti and Aedes albopictus in Northeast Florida.

This study was conducted to determine the efficacy of truck-mounted ultra-low volume applications of pyriproxyfen against Aedes aegypti larvae in artificial water containers and wild adult Ae. albopictus populations in an urban setting. The study was conducted over a 3.5-month period (June-October 2012), during which 3 pyriproxyfen applications were conducted. Beginning 6wk prior to the 1st pyriproxyfen spray, 10 Biogents-Sentinel® traps were used each week to survey the adult Ae. albopictus population at each experimental plot through the end of the study. The treatment and control plots contained specimen cups, each containing 10 laboratory-reared Ae. aegypti larvae, placed at 8, 15, and 23m from the spray line. Emergence inhibition (EI) of 82% or greater was observed among Ae. aegypti larvae exposed to the 3 pyriproxyfen sprays. The EI of these same Ae. aegypti larvae at the 3 distances from the spray ranged from 84% to 92% and were not significantly different. Laboratory analysis of water samples taken from the larval cups independently confirmed the presence of pyriproxyfen. Similar levels of EI were achieved in Ae. aegypti and Ae. albopictus larvae when the measured field concentrations of pyriproxyfen were recreated in laboratory assays. Trap captures of wild adult Ae. albopictus were not markedly reduced following the 1st pyriproxyfen spray, perhaps due to heavy rainfall at the time and the lower rate of pyriproxyfen applied. Within 2wk following Spray 2, however, Ae. albopictus collections from the treatment plot averaged approximately 50% of those from the control plot, and the reduction trend continued following Spray 3.