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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Aerial Application Technology Research » Research » Research Project #425641

Research Project: Aerial Application Technology for Sustainable Crop Production

Location: Aerial Application Technology Research

2014 Annual Report

1a. Objectives (from AD-416):
Objective 1: Optimize aerial spray technologies for on-target deposition and drift mitigation. Subobjective 1A: Characterize effects of spray systems and formulations on droplet size. Subobjective 1B: Enhance spray swath deposition and uniformity. Subobjective 1C: Develop criteria for efficient operation and selection of aerial spray systems. Objective 2: Develop geospatial data processing and analyses methods for crop condition assessment and pest management. Subobjective 2A: Develop variable rate application methods for plant growth regulators (PGRs) and defoliants based on physiological conditions. Subobjective 2B: Develop precision aerial application methods for fertilization and disease control based on biotic conditions.

1b. Approach (from AD-416):
Utilizing engineering and biological principles, laboratory and field studies will be conducted to evaluate the effects of various aerial application parameters, such as spray formulation and droplet size, on aerial application efficiency and biological efficacy. Efforts will focus on the integration of laboratory spray droplet measurements and remote sensing systems to maximize the efficacy of crop production materials while minimizing any off-target impact from these sprays. Plant health and species differences will be determined from remotely sensed data and used to make spray application decisions related to spatial locations and dosages. This project will develop and implement new and improved aerial application technologies for safe, efficient, and sustainable crop production and protection.

3. Progress Report:
Work under this project during FY 2014 resulted in significant progress in improving the efficacy of crop production and protection materials, enhancing the use of remote sensing and precision application in crop production systems, and spray droplet modeling. Tests were conducted in high-speed and low-speed wind tunnels to determine the levels of spray drift mitigation from a number of spray nozzles and formulations, including real-world tank mixes used by aerial applicators. These projects support the EPA Drift Reduction Technology (DRT) Program, DoD-Deployed WarFighter Protection Program, APHIS-Screwworm Barrier Maintenance Program in Panama, and U.S. Navy Entomology Center of Excellence. Biological assessments of various mosquito control products and rates were conducted in new wind tunnel trials and included honeybee toxicity studies. Free smartphone applications were further developed and modified for the iPhone and Google Play platforms that transfer the project's research data into more useful formats for our customers. Remote sensing studies were conducted that identified volunteer cotton plants in ditches and waterways, and diseased cotton plants. Numerous remote sensing flights were conducted to monitor the spread of cotton root rot at two locations in Texas. Both aerial and ground remote sensing studies were conducted to evaluate nitrogen deficiencies in corn and disease severity in rice. A two-camera imaging system for remote sensing studies was developed using consumer-grade cameras and proved to be a good alternative to more expensive camera systems. Significant progress was made in development of spray deposition and drift models, which will aid spray applicators in making spray applications that increase efficacy and minimize off-target spray drift. Project scientists during FY 2014 served on numerous occasions as experts in the aerial application industry and were sought out for advice and consultation by industry and academic research personnel, and by officials with the EPA, Department of Homeland Security, Department of Defense, State Department, USDA-APHIS, and representatives from numerous state agencies and organizations. This project successfully passed a program review by OSQR in 2014 and supports National Programs 305, 304, and 104.

4. Accomplishments
1. Spray adjuvants and airspeed affect droplet size for real world tank mixes. A multitude of data exists detailing the role that either the spray adjuvant or the speed of the aircraft play in atomization of the spray cloud, but little of the research explores how spray droplet size is impacted as both of these factors change. ARS researchers at College Station, Texas, evaluated seven different types of spray adjuvants added to a real-world herbicide tank mix across the full spectrum of fixed-wing aircraft operational speeds for two typical aerial spray nozzles. The objective of the work was to develop a better understanding of how airspeed and adjuvant type work together to influence the resulting spray droplet size. Following standardized testing methods, the work showed that each adjuvant type behaved differently for each nozzle and across the range of airspeeds tested, and that at maximum airspeed the atomization of the spray cloud is dominated by breakup due to airshear with little adjuvant effect. This work has greatly improved understanding of the role adjuvants play in manipulating droplet size in aerial application scenarios, demonstrating that selecting the proper nozzle and application airspeed are critical to optimizing the spray quality of an application.

2. An airborne two-camera imaging system for agricultural remote sensing. Recent advances in imaging technologies have made consumer-grade digital cameras an attractive option for remote sensing due to their low cost, compact size, and user-friendliness. ARS researchers at College Station, Texas, assembled and evaluated an airborne multispectral imaging system based on two identical consumer-grade Canon cameras. One camera captures normal color images while the other obtains near-infrared images with filtering techniques. The color camera is also equipped with a GPS receiver to allow images to be geotagged; a remote control is used to trigger both cameras simultaneously. Geotagged images from the system can be viewed on any image viewer and on Google Earth for quick assessment prior to digital image analysis. The imaging system was tested under various flight and land cover conditions; optimal camera settings were determined for airborne image acquisition. Analysis of example images established that this system has good potential for crop condition assessment, pest detection, precision aerial application, and other agricultural applications.

3. Development of new tracer dye for agricultural sprays. Spray application researchers commonly use tracer dyes to measure the movement of agricultural sprays from the sprayer to the intended targets. These dyes allow quantification of spray deposition and drift without having to use potentially toxic active ingredients that would increase exposure risks to involved personnel. ARS researchers at College Station, Texas, evaluated a new tracer dye, abbreviated as PTSA, and found it to be highly soluble in the spray solution, stable in sunlight, and recoverable from plant and artificial surfaces. The PTSA dye is a significant improvement over dyes currently in use, and opens up a new set of methodologies that applicators and researchers can use in their spray application research studies.

4. Fluorescent imaging technique for quantifying spray deposits on plant leaves. Conventional agricultural insecticide sprays may be ineffective when specific crop pest insects live and feed on the underside of plant leaves. Although electrical charging of these sprays increases the amount of insecticide material that deposits on the underside of leaves, new techniques are needed for measuring droplet deposition on the underside of leaves. ARS researchers at College Station, Texas, developed a new measurement technique using image acquisition of spray droplets mixed with fluorescent dye, and image processing and analysis using readily-available software. Important results from the analysis include the quantity, size, and coverage area of droplets on the leaf. This spray droplet measurement technique will help agricultural applicators accurately assess and improve precision spray applications for effective control of pest insects.

Review Publications
Fritz, B.K., Hoffmann, W.C., Bagley, W.E., Kruger, G., Czaczyk, Z., Henry, R. 2014. Inflence of air shear and adjuvants on spray atomization. In: Sesa, C., editor. Pesticide Formulation and Delivery Systems: 33rd Volume, Sustainability: Contributions from Formulation Technology, STP 1569. ASTM International: West Conshohocken, PA. p. 139-150. doi: 10.1520/STP156920120131.

Fritz, B.K., Hoffmann, W.C., Kruger, G., Henry, R., Hewitt, A., Czaczyk, Z. 2014. Comparison of drop size data from ground and aerial application nozzles at three testing laboratories. Atomization and Sprays. 24(2):181-192.

Hoffmann, W.C., Fritz, B.K., Bagley, W.E., Kruger, G., Henry, R., Czaczyk, Z. 2014. Effects of nozzle spray angle on droplet size and velocity. In: Sesa, C., editor. Pesticide Formulation and Delivery Systems: 33rd Volume, Sustainability: Contributions from Formulation Technology, STP 1569. ASTM International: West Conshohocken, PA. p. 151-173. doi: 10.1520/STP156920120131.

Hoffmann, W.C., Fritz, B.K., Ledebuhr, M. 2014. Evaluation of 1, 3, 6, 8-pyrene tetra sulfonic acid tetra sodium salt (PTSA) as an agricultural spray tracer dye. Applied Engineering in Agriculture. 30(1):25-28.

Yang, C., Westbrook, J.K., Suh, C.P., Martin, D.E., Hoffmann, W.C., Lan, Y., Fritz, B.K., Goolsby, J. 2014. An airborne multispectral imaging system based on two consumer-grade cameras for agricultural remote sensing. Remote Sensing. 6:5257-5278.

Lopez, J., Latheef, M.A., Hoffmann, W.C. 2014. Toxicity and feeding response of adult corn earworm (Lepidoptera: Noctuidae) to an organic spinosad formulation in sucrose solution. Pest Management Science. 2(1):33-41.

Xue, X., Tu, K., Lan, Y. 2013. Effects of pesticides aerial applications on rice quality. Transactions of the Chinese Society for Agricultural Machinery. 44(12):94-98.

Martin, D.E. 2014. A fluorescent imaging technique for quantifying spray deposits on plant leaves. Atomization and Sprays. 24(4):367-373.

Yang, C., Odvody, G.N., Fernandez, C.J., Landivar, J.A., Minzenmayer, R.R., Nichols, R.L., Thomasson, J.A. 2014. Monitoring cotton root rot progression within a growing season using airborne multispectral imagery. Journal of Cotton Science. 18:85-94.

Fritz, B.K., Hoffmann, W.C., Bagley, W.E., Kruger, G., Czaczyk, Z., Henry, R. 2014. Measuring droplet size of agriuclutral spray nozzles - Measurement distance and airspeed effects. Atomization and Sprays. 24(9):747-760.