Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

Atomization and Sprays

Insect pathogens as biological control agents: Back to the future.

Abstract This article aims at finding efficient hyperspectral indices for the estimation of forest sun leaf chlorophyll content (CHL, µg cm leaf − 2 ), sun leaf mass per area (LMA, g dry matter m leaf − 2 ), canopy leaf area index (LAI, m 2 leaf m soil − 2 ) and leaf canopy biomass (B leaf , g dry matter m soil − 2 ). These parameters are useful inputs for forest ecosystem simulations at landscape scale. The method is based on the determination of the best vegetation indices (index form and wavelengths) using the radiative transfer model PROSAIL (formed by the newly-calibrated leaf reflectance model PROSPECT coupled with the multi-layer version of the canopy radiative transfer model SAIL). The results are tested on experimental measurements at both leaf and canopy scales. At the leaf scale, it is possible to estimate CHL with high precision using a two wavelength vegetation index after a simulation based calibration. At the leaf scale, the LMA is more difficult to estimate with indices. At the canopy scale, efficient indices were determined on a generic simulated database to estimate CHL, LMA, LAI and Bleaf in a general way. These indices were then applied to two Hyperion images (50 plots) on the Fontainebleau and Fougeres forests and portable spectroradiometer measurements. They showed good results with an RMSE of 8.2 µg cm − 2 for CHL, 9.1 g m − 2 for LMA, 1.7 m 2 m − 2 for LAI and 50.6 g m − 2 for Bleaf. However, at the canopy scale, even if the wavelengths of the calibrated indices were accurately determined with the simulated database, the regressions between the indices and the biophysical characteristics still had to be calibrated on measurements. At the canopy scale, the best indices were: for leaf chlorophyll content: ND chl  = ( ρ 925  −  ρ 710 )/( ρ 925  +  ρ 710 ), for leaf mass per area: ND LMA  = ( ρ 2260  −  ρ 1490 )/( ρ 2260  +  ρ 1490 ), for leaf area index: D LAI  =  ρ 1725  −  ρ 970 , and for canopy leaf biomass: ND Bleaf  = ( ρ 2160  −  ρ 1540 )/( ρ 2160  +  ρ 1540 ).

Calibration and validation of hyperspectral indices for the estimation of broadleaved forest leaf chlorophyll content, leaf mass per area, leaf area index and leaf canopy biomass

https://www.crec.ifas.ufl.edu/extension/diaprepes/bibliography/PDF/2BioCont381.pdf

Application technology and environmental considerations for use of entomopathogenic nematodes in biological control

Spray drift assessment encompasses classification of the capacity of each sprayer/technology/setting combination to reduce or avoid the spray drift risk, as well as drift measurement to define buffer zones mandated during pesticide application. Compounding the challenge of these tasks is the great variability of field evaluation results from environmental conditions, spray application technology, canopy structure, and measurement procedures. This study, performed in Spanish context, evaluates the effects of different parameters on comparative measurements of ground and airborne spray drift employing the ISO22866:2005 protocol. Four configurations of air blast sprayers, derived from two fan airflow rates and two nozzle types (conventional and air-induction), were tested in orchard and vineyard at late growth stage. Spray drift curves were obtained, from which corresponding Drift Values (DVs) were calculated using an approximation of definite integral. Both sprayer settings and environmental variables statistically affect spray drift total amounts and result variability. PCA analysis showed that nozzle type and wind speed characteristics explained 51% and 24% of the variance, respectively. In particular, mean wind direction influence ground sediments (Pr < 0.01) and maximum wind speed strongly influence airborne drift value (Pr < 0.0001). The wind characteristics concealed the influence of adopted fan airflow rates on final spray drift assessment results. The effect of uncontrollable environmental conditions makes objective and comparative tests difficult.

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Ground Deposition and Airborne Spray Drift Assessment in Vineyard and Orchard: The Influence of Environmental Variables and Sprayer Settings

Spray drift potential, spray coverage, droplet size, and spray pattern width for various sizes of air induction and conventional flat-fan nozzles with equivalent orifice areas were investigated and compared under laboratory conditions. Droplet sizes were measured with a laser imaging system; spray coverage on water-sensitive paper (WSP) was evaluated with a boom sprayer at a constant travel speed in a greenhouse, and ground and airborne spray deposits were determined in a wind tunnel at two wind velocities (2.5 and 5.0 m/s). Tests were also conducted to evaluate the effect of air-intake holes being sealed or open on spray characteristics of air induction nozzles. With the equivalent nominal flow rate, air induction nozzles had approximately 2.1 to 2.75 times larger exit orifice areas than the conventional nozzles. With the equivalent orifice area and equal liquid flow rate, there was no significant difference in droplet size, spray pattern width, spray coverage, ground spray deposit, and airborne deposit among regular air induction nozzles, air induction nozzles with two sealed air-intake holes, and conventional flat-fan nozzles. Spray characteristics of air induction nozzles could be achieved by conventional nozzles with the equivalent orifice size operated at the reduced operating pressure.

Spray characteristics and drift reduction potential with air induction and conventional flat-fan nozzles

The efficiency of foliar spray applications is influenced by the evaporation and residual pattern of pesticide droplets on targets. Evaporation time and maximal coverage area of a single droplet from 246 to 886 m in size at relative humidity (RH) ranging from 30% to 90% were measured with sequential images under controlled conditions. Droplets were placed on targets inside an environmentally controlled chamber under a stereoscope and a high-definition digital camera. The spray mixtures used to form droplets included different combinations of water, a nonionic colloidal polymer drift retardant, an alkyl polyoxyethylene surfactant, and two commercially available insecticides. The droplet evaporation was investigated on crabapple leaf surfaces, and hydrophilic and hydrophobic glass slide surfaces. Adding surfactant into spray mixtures greatly increased droplet coverage area on the surfaces, while droplet evaporation time was greatly reduced. For a 343 m droplet on a crabapple leaf at 60% RH, the evaporation time decreased from 70 to 50 s and the maximal coverage area increased from 0.366 to 0.890 mm 2 after the surfactant was added into the spray mixture containing water and insecticide. Adding the drift retardant into the spray mixture slightly increased the droplet evaporation time and decreased the droplet coverage area. In addition, changing the target surface from the hydrophilic slide to the hydrophobic slide greatly increased the droplet coverage area and reduced the droplet evaporation time. Increasing RH increased the droplet evaporation time greatly but did not change the coverage area. The droplet evaporation time and coverage area increased exponentially as the droplet size increased. Therefore, droplet size, surface characteristics of the target (waxy or non-waxy), RH, and chemical composition of the spray mixture (water alone, pesticide, additives) should be included as important factors that can affect the efficacy and efficiency of pesticide applications.

https://pubag.nal.usda.gov/pubag/downloadPDF.xhtml?id=30444&content=PDF

Evaporation and Deposition Coverage Area of Droplets Containing Insecticides and Spray Additives on Hydrophilic, Hydrophobic, and Crabapple Leaf Surfaces

Effects of pressure differentials on the viability and infectivity of entomopathogenic nematodes

Information is lacking on spray techniques to improve deposit uniformity within nursery canopies and reduce off-target loss on the ground and via spray drift from the treated area. Spray deposits at various elevations within crabapple trees 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. Airborne deposits at three elevations on sampling towers and on the ground at several distances from the sprayer were also investigated with the three spray treatments in an open area without trees. To compare field test results, wind tunnel experiments were conducted to assess spray deposits on the floor beyond 0.4 m downwind distance from the nozzles and airborne deposits at 2.1 m downwind from the spray discharge point with the three spray techniques without air assist. Droplet size distributions across spray patterns without air assist were measured with a laser particle/droplet image analysis system. In general, there was 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 tree canopies received over 4 to 14.5 times as much spray deposit as actually needed from all treatments, and a large portion of spray volume deposited on the ground. Compared with conventional hollow-cone nozzles, drift reduction from air-induction nozzles or the spray mixture with drift retardant treatment was significant in wind tunnel tests but was not significant in field tests.

Foliar deposition and off-target loss with different spray techniques in nursery applications

Many insect and disease problems occur in specific plant canopy locations and cannot be managed with systemic pesticides. Diseases such as Asian soybean rust (ASR) (Phakopsora pachyrhizi) infect plant material deep inside a canopy that is difficult to target. Field studies were established in north central Ohio to determine the effect of different application strategies on targeting of foliar pesticide in narrow-row (18 cm) soybean plantings. Several different application factors were tested, including spray quality, nozzle type, air-assistance, and spray volume. In 2005, the spray mix included a fungicide used for ARS management. In 2006, in addition to the fungicide, an insecticide for soybean aphid management was included. Plant samples were removed from each test plot, and stems and leaves from the bottom third and middle third of the plant were separated for individual analysis. Overall, there was significantly less active ingredient found in the lower third of the canopies than the middle third, and significantly less pesticide residue was found on stems than leaves from the same canopy location. Significantly more fungicide residue was found on lower leaves treated by the medium-quality XR8004 flat-fan nozzle in 2005 than the coarse-quality XR8005 flat-fan nozzle. There were no differences in fungicide residue found on middle canopy leaves between the fine, medium, and coarse quality flat-fan nozzles. The twin-fan pattern nozzles (Turbo Duo and TwinJet) produced the lowest amounts of fungicide residue on the lower leaves in 2005. The mechanical canopy opener produced significantly higher fungicide residues on middle canopy leaves than all other treatments. The Jacto air-assist sprayer using JA3 hollow-cone nozzles produced the highest fungicide residues on lower canopy leaves in 2005. There were some statistical differences between the amounts of fungicide and insecticide residue found on plant tissue in 2006 because of the high amount of variability in the sample data. Overall in 2006, the higher volume XR8004 treatment (187 L ha-1) and the twin-fan TTJ60-11003 treatment at 145 L ha-1 performed similar to the Jacto sprayer making applications at 145 L ha-1 using either flat-fan or hollow-cone nozzles. In general, higher volume applications produced higher amounts of fungicide and insecticide residue on leaves from the middle of the canopy for conventional flat-fan and air-assist applications. Spray volume had less affect on residues measured on leaves from the lower canopy area. Across two years of different canopies at the same spray volume (145 L ha-1), the Jacto sprayer using JA3 hollow-cone nozzles produced more fungicide residue on middle canopy stems and lower canopy leaves than the medium-quality XR8004 flat-fan nozzle.

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Determining the Influence of Spray Quality, Nozzle Type, Spray Volume, and Air-Assisted Application Strategies on Deposition of Pesticides in Soybean Canopy

R. C. Derksen

Papers

Spray characteristics and drift reduction potential with air induction and conventional flat-fan nozzles

Evaporation and Deposition Coverage Area of Droplets Containing Insecticides and Spray Additives on Hydrophilic, Hydrophobic, and Crabapple Leaf Surfaces

Effects of pressure differentials on the viability and infectivity of entomopathogenic nematodes

Foliar deposition and off-target loss with different spray techniques in nursery applications

Determining the Influence of Spray Quality, Nozzle Type, Spray Volume, and Air-Assisted Application Strategies on Deposition of Pesticides in Soybean Canopy