W. Clint Hoffmann

Using a Surface Plasmon Resonance Biosensor for Rapid Detection of Salmonella Typhimurium in Chicken Carcass

Chicken is one of the most popular meat products in the world. Salmonella Typhimurium is a common foodborne pathogens associated with the processing of poultry. An optical Surface Plasmon Resonance (SPR) biosensor was sensitive to the presence of Salmonella Typhimurium in chicken carcass. The Spreeta biosensor kits were used to detect Salmonella Typhimurium on chicken carcass successfully. A taste sensor like electronic tongue or biosensors was used to basically “taste” the object and differentiated one object from the other with different taste sensor signatures. The surface plasmon resonance biosensor has potential for use in rapid, real-time detection and identification of bacteria, and to study the interaction of organisms with different antisera or other molecular species. The selectivity of the SPR biosensor was assayed using a series of antibody concentrations and dilution series of the organism. The SPR biosensor showed promising to detect the existence of Salmonella Typhimurium at 1 × 106 CFU/ml. Initial results show that the SPR biosensor has the potential for its application in pathogenic bacteria monitoring. However, more tests need to be done to confirm the detection limitation.

DROPLET-SIZE CHARACTERIZATION OF HANDHELD ATOMIZATION EQUIPMENT TYPICALLY USED IN VECTOR CONTROL

ABSTRACT The atomization characteristics of 4 handheld sprayers (Leco P-1, Colt ULV Aerosol Generator, ULVAFAN MK2, Turbair ElectraFan 12) and a Stihl SR400 backpack sprayer were evaluated with the use of water- and oil-based solutions. The effects on droplet-size spectrum (i.e., droplet size) for 3 insecticides (Tempo SC Ultra®, Anvil 10+10®, and Aqua-Reslin®) were also evaluated. Generic solutions were used to simulate the physical properties of the active-ingredient solutions in some tests. Significant differences were observed in the droplet spectrum generated by the different sprayers. The volume median diameter of the equipment tested ranged from 14.9 to 90.5 µm for the water-based solutions and from 11.7 to 92.4 µm for the oil-based solutions. The Colt ULV sprayer was the only one tested that complied with label requirements for aerosols, yielding acceptable DV0.5 values of 14.9–16.0 µm with water-based Aqua-Reslin and 14.1 µm with Anvil 10+10. The information presented will allow equipment operators to make an informed decision when selecting equipment and operational parameters.

An Airborne Multispectral Imaging System Based on Two Consumer-Grade Cameras for Agricultural Remote Sensing

This paper describes the design and evaluation of an airborne multispectral imaging system based on two identical consumer-grade cameras for agricultural remote sensing. The cameras are equipped with a full-frame complementary metal oxide semiconductor (CMOS) sensor with 5616 × 3744 pixels. One camera captures normal color images, while the other is modified to obtain near-infrared (NIR) images. The color camera is also equipped with a GPS receiver to allow geotagged images. A remote control is used to trigger both cameras simultaneously. Images are stored in 14-bit RAW and 8-bit JPEG files in CompactFlash cards. The second-order transformation was used to align the color and NIR images to achieve subpixel alignment in four-band images. The imaging system was tested under various flight and land cover conditions and optimal camera settings were determined for airborne image acquisition. Images were captured at altitudes of 305–3050 m (1000–10,000 ft) and pixel sizes of 0.1–1.0 m were achieved. Four practical application examples are presented to illustrate how the imaging system was used to estimate cotton canopy cover, detect cotton root rot, and map henbit and giant reed infestations. Preliminary analysis of example images has shown that this system has potential for crop condition assessment, pest detection, and other agricultural applications.

Evaluation of Spray Drift Using Low-Speed Wind Tunnel Measurements and Dispersion Modeling

The EPAs proposed test plan for the validation testing of pesticide spray drift reduction technologies DRTs for row and field crops, focusing on the evaluation of ground application systems using the low-speed wind tunnel measurements and dispersion modeling, was evaluated. Relative drift reduction potential for a given DRT tested in a low-speed wind tunnel is derived from airborne droplet size measure- ments and airborne and deposited liquid volume measurements downwind from the spray nozzle. Mea- surements of droplet size and deposition data were made in a low-speed wind tunnel using standard reference nozzles. A blank emulsifiable concentration spray was applied at two different wind speeds. The wind tunnel dispersion WTDISP model was used to evaluate the drift potentials of each spray using the droplet size and spray flux measured in the wind tunnel. The specific objectives were 1 the evaluation of model accuracy by comparison of modeled downwind deposition to that measured in the wind tunnel, 2 the evaluation of drift reduction potential of the spray nozzles relative to a reference nozzle, and 3 the determination of low-speed wind tunnel data collection requirements for model input to optimize the evalu- ation process. The modeled deposition data did not compare well to the measured deposition data, but this was expected as the model was not meant to be used for this purpose. The tested nozzles were rated using the International Standards Organization drift classification standard. The drift ratings generally showed trends of larger droplet producing nozzles having greater drift reduction ratings. An examination of several scenarios using reduced model input requirements, which would decrease the low-speed wind tunnel data collection time, did not show any conclusive results. They suggest that further testing and refinement of the data collection process and the WTDISP model may support wider use of this system for the assessment of DRTs.

Effects of Wind Speed on Aerosol Spray Penetration in Adult Mosquito Bioassay Cages

ABSTRACT Bioassay cages are commonly used to assess efficacy of insecticides against adult mosquitoes in the field. To correlate adult mortality readings to insecticidal efficacy and/or spray application parameters properly, it is important to know how the cage used in the bioassay interacts with the spray cloud containing the applied insecticide. This study compared the size of droplets, wind speed, and amount of spray material penetrating cages and outside of cages in a wind tunnel at different wind speeds. Two bioassay cages, Center for Medical, Agricultural and Veterinary Entomology (CMAVE) and Circle, were evaluated. The screen materials used on these cages reduced the size of droplets, wind speed, and amount of spray material inside the cages as compared to the spray cloud and wind velocity outside of the cages. When the wind speed in the dispersion tunnel was set at 0.6 m/sec (1.3 mph), the mean wind speed inside of the CMAVE Bioassay Cage and Circle Cage was 0.045 m/sec (0.10 mph) and 0.075 m/sec (0.17 mph), respectively. At air velocities of 2.2 m/sec (4.9 mph) in the dispersion tunnel, the mean wind speed inside of the CMAVE Bioassay Cage and Circle Cage was 0.83 m/sec (1.86 mph) and 0.71 m/sec (1.59 mph), respectively. Consequently, there was a consistent 50–70% reduction of spray material penetrating the cages compared to the spray cloud that approached the cages. These results provide a better understanding of the impact of wind speed, cage design, and construction on ultra-low-volume spray droplets.

Aerial electrostatic-charged sprays for deposition and efficacy against sweet potato whitefly (Bemisia tabaci) on cotton.

BACKGROUND The efficacy of aerial electrostatic-charged sprays was evaluated for spray deposit characteristics and season-long control of sweet potato whitefly (SWF), Bemisia tabaci Genn. biotype B (aka B. argentifolii Bellows & Perring), in an irrigated 24 ha cotton field. Treatments included electrostatic-charged sprays at full and half active ingredient (AI) label rate, uncharged sprays and conventional sprays applied with CP nozzles at full label rate with several different insecticides. RESULTS Spray droplet size was significantly smaller for electrostatic-charged sprays than for conventional sprays in top- and mid-canopy locations. The seasonal mean numbers of viable eggs and live large nymphs on cotton treated with electrostatic-charged sprays were comparable with those on cotton treated with conventional applications. Lethal concentration (LC(50)) for adults for electrostatic-charged sprays was comparable with that for conventional sprays. CONCLUSION The amenability of electrostatic-charged sprays to a wide array of pesticides with different chemistries should be a useful tool in combating insect resistance. Results reported here suggest that the potential exists for obtaining increased efficacy against whiteflies using an electrostatic spray charging system, and that additional research will be required to improve charge-to-mass (Q/M) ratio in order to increase deposition of pest control materials to the lower surfaces of cotton leaves where the whiteflies reside.

AEROSOL SAMPLING: COMPARISON OF TWO ROTATING IMPACTORS FOR FIELD DROPLET SIZING AND VOLUMETRIC MEASUREMENTS

Abstract This article compares the collection characteristics of a new rotating impactor Florida Latham Bonds (FLB) sampler for ultrafine aerosols with a mimic of the industry standard (Hock-type). The volume and droplet-size distribution collected by the rotating impactors were measured via spectroscopy and microscopy. The rotary impactors were colocated with an isokinetic air sampler for a total volume flux measurement and a laser diffraction instrument for droplet-size distribution measurement. The measured volumetric flux and droplet-size distribution collection efficiencies were compared across 3 wind speeds (1, 1.8, and 3.5 m/sec). The FLB sampler had higher flux collection efficiencies than the Hock-type sampler. The FLB sampler collected 89%, 87%, and 98% of the total volume available per unit area at 1, 1.8, and 3.5 m/sec, respectively, whereas the Hock-type sampler collected 68%, 19%, and 21% of across the same wind speeds. Changes in wind speed had less impact and resulted in less data variability for the FLB sampler.

Identification of Stink Bugs Using an Electronic Nose

Stink bugs are recognized as pests of several economically important crops, including cotton, soybean and a variety of tree fruits. The Cyranose 320 was used for the classified investigation of stink bug. Stink bugs including males and females of the southern green stink bugs, Nezara viridula, were collected from crop fields around College Station, TX. Results show that the released chemicals and chemical intensity are both critical factors, which determine the rate that the Cyranose 320 correctly identified the stink bugs. The Cyranose 320 shows significant potential in identifying stink bugs, and can classify stink bug samples by species and gender.

Spray Adjuvant Effects on Droplet Size Spectra Measured by Three Laser-Based Systems in a High-Speed Wind Tunnel

Spray droplet size has long been recognized as the most important variable that aerial applicators can influence to mitigate spray drift from the application site. There are several different technologies that are used by researchers to measure droplet size from spray nozzles. The objective of these studies was to determine the influence of eight spray adjuvants on the droplet size spectrum produced by two nozzles in a high-speed wind tunnel when characterized using three different droplet size measurement systems. The adjuvant, nozzles, and airspeeds used in these studies are commonly used by aerial applicators. Three droplet sizing systems (Malvern laser diffraction, PMS optical array probe, and LaVision laser imaging) were simultaneously operated to measure the spray droplet size spectra for each adjuvant, airspeed, and nozzle combination. Two spray nozzles (a D6-46 nozzle and a D2 straight stream nozzle) were evaluated in a high-speed wind tunnel at airspeeds of 45 and 58 m/sec. There were significant differences in the droplet size spectra produced by the eight spray adjuvants tested. There were also significant differences between the droplet size values reported by the three measurement systems (Malvern, LaVision, and PMS) evaluated; however, there was considerable agreement trendwise. In general, the Malvern reported smaller spray droplet size spectra values than the LaVision, while the PMS system generally reported the largest spray droplet size spectra values. These tests are the first reported studies where all three droplet sizing systems were operated simultaneously.

Field scale evaluation of spray drift reduction technologies from ground and aerial application systems

The objective of this work is to evaluate a proposed test plan for the validation testing of pesticide spray drift reduction technologies DRTs for row and field crops, focusing on the testing of ground and aerial application systems under full-scale field evaluations. The measure of performance for a given DRT tested under field conditions is the downwind deposition as measured on horizontal fallout collectors. Ground and aerial application equipment were evaluated for in-swath and downwind deposition of sprays as applied by both a reference system and a drift reducing technology. For this study, the reference system was defined as a spray boom outfitted with the ASABE Fine/Medium boundary reference nozzles. For the ground system, the drift reducing system tested was a ground sprayer outfitted with an air-induction version of the reference nozzle. The aerial system DRT was a flat fan nozzle specifically designed for aerial application usage. Downwind deposition was measured from the edge of the swath out to 100 m downwind. Additionally, the airborne portion of the spray remaining suspended in the air at 50 m downwind was measured. There were a number of confounding issues with the measured data including poor recovery of deposits and non-ideal wind directions during specific replications. Even with these issues, the drift reduc- tion between the reference and DRT system measured in the field for the aerial trials was similar to that estimated using the agricultural dispersion model. A number of additional improvements and checks are suggested prior to further field evaluations.