Influence of spray droplet size on paraquat and glyphosate efficacy
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Influence of Spray Droplet Size on Paraquat and Glyphosate Efficacy PowerPoint PPT Presentation


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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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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

  • Determines the uniformity

  • Determines the coverage

  • Determines the drift potential


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?


What’s new in nozzle technology?

  • Nozzles designed to reduce drift

  • Improved drop size control


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


1/2 of spray volume = smaller droplets

VMD

1/2 of spray volume = larger droplets


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.


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 11-19 km/hN-E 3-10 km/h


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


DropletScan used to analyze droplets:

Water Sensitive Paper

Software & lock-key

Color Scanner

Portable computer

Color Printer

System Components


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.


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


Important Droplet Statistics:

VMD

(50%)

Operational Area

VD0.9

(90%)

VD0.1

(10%)


Collection Procedure:


Sample cards:

XR

TT

AI

38 L/ha

XR

TT

AI

19 L/ha

XR

TT

AI

76 L/ha


Results and Discussion


All Studies - Dv0.5 (µm) (VMD) Means

19

38

76

110015

11003

11006


All Studies – Dv0.1 (µm) Means:

110015

11003

11006


All Studies – Number of Droplets Below 200 Microns

110015

11006

11003


Results for Efficacy Studies:

Early Post (Oats Only)

Late Post (Oats Only)


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.


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.


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.


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.


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.


Thanks


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