Kansas State University Biological and Agricultural Engineering Department 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

Kansas State University Biological and Agricultural Engineering Department Nozzle is still an important part of the application process! l Determines the application rate l Determines the uniformity l Determines the coverage l Determines the drift potential

Kansas State University Biological and Agricultural Engineering Department Determines coverage: l Need knowledge of the product being used. –Systemic –Contact l What is the target? –Soil or canopy? –Grass or broadleaf (smooth, hairy, waxy)? –Orientation and time of day?

Kansas State University Biological and Agricultural Engineering Department What’s new in nozzle technology? l Nozzles designed to reduce drift l Improved drop size control

Kansas State University Biological and Agricultural Engineering Department XR Flat-fan and Turbo Flat-fan compared to Venturi Style Nozzle 5.0 MPH wind at 40 psi XR vs TurboDropTurbo Flat vs Turbo Drop

Kansas State University Biological and Agricultural Engineering Department 1/2 of spray volume = larger droplets VMD 1/2 of spray volume = smaller droplets

Kansas State University Biological and Agricultural Engineering Department Objective of this study: l Field measure the spray droplet characteristics of a venturi flat-fan nozzle compared to extended range and turbo flat-fan nozzles.

Kansas State University Biological and Agricultural Engineering Department 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 CropOats ‘Don’(Exp. 1 and 2) WeedsVelvetleaf, 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, 2000May 5, 2000Aug. 18, 2000Sept. 1, 2000 Oat/weed Size: 15 cm51 cm10 cm21 cm Temperature:20 C25 C21 C24C R. H.:50%56%75%71% Wind: W-NW 8-10 km/hSE 5-8 km/hNE km/hN-E 3-10 km/h

Kansas State University Biological and Agricultural Engineering Department 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 ( 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

Kansas State University Biological and Agricultural Engineering Department DropletScan  used to analyze droplets: System Components

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

Kansas State University Biological and Agricultural Engineering Department Important Droplet Statistics: l D v0.1 (µm) - 10% of the spray volume in drops < number reported l D v0.5 (µm) - 50% of the spray volume in drops < number reported (also is VMD- volume median diameter) l D v0.9 (µm) - 90% of the spray volume in drops < number reported l Number of droplets under 200 microns

Kansas State University Biological and Agricultural Engineering Department Important Droplet Statistics: Operational Area

Kansas State University Biological and Agricultural Engineering Department Collection Procedure:

Kansas State University Biological and Agricultural Engineering Department XR AI TT XR AI Sample cards: 19 L/ha 38 L/ha 76 L/ha

Kansas State University Biological and Agricultural Engineering Department Results and Discussion

Kansas State University Biological and Agricultural Engineering Department All Studies - D v0.5 (µm) (VMD) Means

Kansas State University Biological and Agricultural Engineering Department All Studies – D v0.1 (µm) Means:

Kansas State University Biological and Agricultural Engineering Department All Studies – Number of Droplets Below 200 Microns

Kansas State University Biological and Agricultural Engineering Department Results for Efficacy Studies: Early Post (Oats Only)Late Post (Oats Only)

Kansas State University Biological and Agricultural Engineering Department Summary of findings D v0.5 (µm) (VMD): l In general as the spray volume increased the D v0.5 (µm) (VMD) also increased. l The venturi flat-fan tips produced larger droplets than the turbo flat- fans which produced droplets larger than the extended range flat-fan tips.

Kansas State University Biological and Agricultural Engineering Department l The extended range flat-fan had the lowest micron size across all volumes with the 19 L/ha being the smallest. l The turbo flat-fans were the next smallest. l The venturi flat-fans had the largest micron size for this category. Summary of findings D v0.1 (µm):

Kansas State University Biological and Agricultural Engineering Department Summary of Findings - Droplet Count under 200 microns: l At 19 L/ha the extended range flat- fans nearly tripled the venturi flat- fans for number of droplets created under 200 microns. l 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.

Kansas State University Biological and Agricultural Engineering Department Summary of findings for the Efficacy (oats) Studies: l 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. l 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.

Kansas State University Biological and Agricultural Engineering Department Take Away Message: l 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.

Kansas State University Biological and Agricultural Engineering Department Thanks