An Overview of Spray Drift Reduction Testing of Spray Nozzles

1. An Overview of Spray Drift Reduction Testing of Spray Nozzles Brad Fritz, Clint Hoffmann, Jonathan Thornberg, Bill Bagley, Norm Birchfield, and Jay Ellenberger

2. Background • Development of a testing program for measuring drift reduction technologies (DRTs) was initiated by the U.S. EPA in 2004; • Drift reduction technologies can be spray nozzles, sprayer modifications, spray delivery assistance, spray property modifiers (adjuvants), and/or landscape modifications.

3. Background • This work is a continuation of research examining methods for testing and rating DRTs and is done in conjunction with EPA, product manufacturers and others • Testing protocols include testing for ground, aerial, and orchard spray applications. • Testing can be conducted in wind tunnels or under field conditions.

4. High Speed Wind Tunnel Testing

5. USDA-ARS Standard Operating Procedures* • USDA-4.1: PERSONNEL TRAINING AND LASER SAFETY RECORDS. Sep, 2007. • USDA-4.2: MEASUREMENT OF PHYSICAL PROPERTIES OF LIQUIDS. Sep, 2007. • USDA-4.3: RECEPTION, STORAGE, AND DISTRIBUTION OF ACTIVE CHEMICALS. Sep, 2007. • USDA-4.4: DETERMINING CROSS-SECTION AVERAGE DROP-SIZE DISTRIBUTIONS OF SPRAYS. Sep. 2007. • USDA-4.5: CORRECTIVE AND PREVENTIVE ACTION. Sept. 2007. • USDA-5.1: LASER SAFETY PROTOCOL. Nov, 2007. * - These are only for the College Station group

6. Proposed Reference System • For a reduction to occur, one must select a reference to reduce from; • Measurements of candidate test systems are compared to a reference spray system based on the ASAE S572 standard for droplet size. • Use the ASAE S572 reference nozzle associated with the fine/medium boundary.: 110° flat-fan nozzle operated at 43.5 psi.

7. Testing of Spray Nozzles as DRT • This is an application of the HSWT Protocol to spray nozzles as DRT; • 4 spray nozzles (Reference, N1, N2, and N3) were evaluated in the HSWT and the droplet spectra was measured via laser diffraction; • N1: Hypro ULD 120-04; • N2: Teejet AI 11003 VS; • N3: CP11TT 4008. • NOTE: These nozzles were ones that were submitted to EPA for initial testing

8. Droplet Size Data from Nozzles

9. AGDISP Modeling (Ver. 8.21): Standard Conditions Meteorological Conditions Aircraft and Setup

10. Droplet Size Data Input

11. AGDISP Output Droplet Size Statistics Application Efficiency: Amount of material deposited in the target area Downwind Deposition: Amount of material deposition on ground 0-10 m from field edge Airborne Drift: Portion of spray in air after 10 m These sum to 100%.

12. Results – 120 mph

13. Results – 140 mph

14. Drift Reduction from Nozzles

15. Aerial Application Industry BMP:½ to 1 swath offset

16. Combined Drift Reduction with Nozzle + Industry BMP

17. Drift Reduction Ratings - LERAP UK’s Local Environmental Risk Assessments for Pesticides (LERAP) Low Drift rating system was used. This system has four rating categories defined as follows: • No LERAP – Low drift rating- • 0 to 25% reduction as compared to reference system • LERAP – Low Drift – One Star • 25 to 50% reduction as compared to reference system • LERAP – Low Drift – Two Star ** • 50 to 75% reduction as compared to reference system • LERAP – Low Drift – Three Star *** • 75% or greater reduction as compared to reference system

18. Drift Reduction Ratings - ISO

19. Drift Reduction Ratings with Industry BMP @ 120 mph

20. Drift Reduction Ratings with Industry BMP @ 140 mph

21. Conclusions • As compared to the reference nozzle, the three spray nozzles reduced spray drift by 40-84% (i.e. VMDs 60-80 µm larger than the reference nozzle); • The aerial application industry’s Best Management Practices (BMP) of ½ to 1 swath offset increased drift reduction to %. • These results demonstrate the possibility of combining multiple drift reduction techniques/technologies to greatly reduce spray drift. • This program could eventually impact label language • Buffer zone restrictions • Wind speed restrictions • Etc….

22. Thank You