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Influence of Spray Droplet Size on Paraquat and Glyphosate Efficacy

Influence of Spray Droplet Size on Paraquat and Glyphosate Efficacy. Robert Wolf Biological and Agricultural Engineering Dept. Cathy Minihan and Dallas Peterson Department of Agronomy. Nozzle is still an important part of the application process!. Determines the application rate

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Influence of Spray Droplet Size on Paraquat and Glyphosate Efficacy

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  1. Influence of Spray Droplet Size on Paraquat and Glyphosate Efficacy Robert Wolf Biological and Agricultural Engineering Dept. Cathy Minihan and Dallas Peterson Department of Agronomy

  2. Nozzle is still an important part of the application process! • Determines the application rate • Determines the uniformity • Determines the coverage • Determines the drift potential

  3. Determines coverage: • Need knowledge of the product being used. • Systemic • Contact • What is the target? • Soil or canopy? • Grass or broadleaf (smooth, hairy, waxy)? • Orientation and time of day?

  4. What’s new in nozzle technology? • Nozzles designed to reduce drift • Improved drop size control

  5. XR Flat-fan and Turbo Flat-fan compared to Venturi Style Nozzle5.0 MPH wind at 40 psi XR vs TurboDrop Turbo Flat vs Turbo Drop

  6. 1/2 of spray volume = smaller droplets VMD 1/2 of spray volume = larger droplets

  7. Objective of this study: • Field measure the spray droplet characteristics of a venturi flat-fan nozzle compared to extended range and turbo flat-fan nozzles.

  8. Materials and Methods: Experiments: Exp. 1 and 2 Early and Late Postemergence Grass Exp. 3 and 4 Early and Late Postemergence Broadleaves Location: Manhattan, KS Exp. Design: 2 x 3 x 3 factorial with 4 reps Plot Size: 3 x 9 m with 1.5 m buffer Crop Oats ‘Don’(Exp. 1 and 2) Weeds Velvetleaf, pigweed, and morning glory (Exp. 3 and 4) Visual Ratings: 1, 2, and 4 weeks after treatment Herbicides (2): Paraquat, 0.14 kg/ha Glyphosate, 0.23 kg/ha Application Conditions: Exp. 1Exp. 2Exp. 3Exp. 4 Date: April 19, 2000 May 5, 2000 Aug. 18, 2000 Sept. 1, 2000 Oat/weed Size: 15 cm 51 cm 10 cm 21 cm Temperature: 20 C 25 C 21 C 24C R. H.: 50% 56% 75% 71% Wind: W-NW 8-10 km/h SE 5-8 km/h NE 11-19 km/h N-E 3-10 km/h

  9. Materials and Methods cont.: Spray Tips (3): Extended Range Flat-fan (XR) Turbo Flat-fan (TT) Air Induction Flat-fan (AI) Spray Volumes (3): 19 L/ha (110015 orifice tips) 38 L/ha (11003 orifice tips) 76 L/ha (11006 orifice tips) Application Ground Speed: 10 km/h Spray Pressure: 276 kPa Spray Tip Spacing: 76 cm Canopy Boom Height: 51 cm

  10. DropletScan used to analyze droplets: Water Sensitive Paper Software & lock-key Color Scanner Portable computer Color Printer System Components

  11. What is DropletScan ? • A software program that will allow accurate and rapid measure of spray droplet impressions on water-sensitive paper. • Developed at K-State by Devore Systems - modeled after ‘Crumbscan’, a software program to determine hole sizes in slices of bread.

  12. Important Droplet Statistics: • Dv0.1 (µm) - 10% of the spray volume in drops < number reported • Dv0.5 (µm) - 50% of the spray volume in drops < number reported (also is VMD- volume median diameter) • Dv0.9 (µm) - 90% of the spray volume in drops < number reported • Number of droplets under 200 microns

  13. Important Droplet Statistics: VMD (50%) Operational Area VD0.9 (90%) VD0.1 (10%)

  14. Collection Procedure:

  15. Sample cards: XR TT AI 38 L/ha XR TT AI 19 L/ha XR TT AI 76 L/ha

  16. Results and Discussion

  17. All Studies - Dv0.5 (µm) (VMD) Means 19 38 76 110015 11003 11006

  18. All Studies – Dv0.1 (µm) Means: 110015 11003 11006

  19. All Studies – Number of Droplets Below 200 Microns 110015 11006 11003

  20. Results for Efficacy Studies: Early Post (Oats Only) Late Post (Oats Only)

  21. Summary of findings Dv0.5 (µm) (VMD): • In general as the spray volume increased the Dv0.5 (µm) (VMD) also increased. • The venturi flat-fan tips produced larger droplets than the turbo flat-fans which produced droplets larger than the extended range flat-fan tips.

  22. Summary of findings Dv0.1 (µm): • The extended range flat-fan had the lowest micron size across all volumes with the 19 L/ha being the smallest. • The turbo flat-fans were the next smallest. • The venturi flat-fans had the largest micron size for this category.

  23. Summary of Findings - Droplet Count under 200 microns: • At 19 L/ha the extended range flat-fans nearly tripled the venturi flat-fans for number of droplets created under 200 microns. • At 38 L/ha the extended range flat-fans more than doubled both the turbo and venturi flat-fans for number of droplets created under 200 microns.

  24. Summary of findings for the Efficacy (oats) Studies: • Efficacy data collected indicates that the venturi and turbo flat-fan tips performed equally well or better than the extended range flat-fan tips regardless of herbicide and timing. • Spray volume did not affect control of oats at early postemergence, but control was better with 19 and 38 L/ha than 76 L/ha at late postemergence regardless of herbicide.

  25. Take Away Message: • Pesticide applicators can achieve good weed control while minimizing water requirements by utilizing low spray volumes using venturi and turbo flat-fan tips risking less chance for drift.

  26. Thanks

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