Application Concerns for Pasture Management

Robert E. WolfExtension Specialist Application

Technology

Biological and Agricultural Engineering

Changes in the Application Industry!

• Historically inefficient process• Increased cost of chemicals• Rates are changing (< an ounce/acre)• More pest specific products (foliar)• Biotechnology and GMO’s – Roundup Ready, Bt’s• More sophisticated equipment (electronics) $$$• Environmental impact (water and air)

– Easy to measure!– Drift!!!

• Variable rates• Site-specific

Equipment cost today?How much do these machines cost?

Equipment cost today?

How much do these machines cost?

Application Equipment

Manual Sprayers–Compressed air

–Knapsack

Spray Management Valve

CF Valve

Easy Spray Valve

Power Hydraulic

Sprayer– Low-pressure– High pressure

Application Equipment

Invasive Species Control

Nozzles are important because:

• Control the amount – GPA.

• Determine uniformity of application.

• Affects the coverage.

• Influences the drift potential.

1. Control the Amount applied:

Nozzle Flow Rate is affected by:

• Orifice size• Pressure• Solution

characteristics

Page 9 – TeeJet Guide

Calibration!!!!

Ensuring that the spray output is what it is supposed to be!

Calculations

GPA=

5940

#$!@&%!#$!@&%!

Calibration/Nozzle Selection

• What is the first step?• Use label to select the

– application volume– product rate

• Choose an appropriate travel speed• Effective width of application

– nozzle spacing• Calculate GPM – Flow rate per nozzle• Select the correct size of nozzle!

Flow rate equation

GPMGPA x MPH x SW(ft)

495

GPMGPA x MPH x W in

( )

5940

or

(5940/12” = 495)Page 14 – TeeJet Guide

5940 or 495 = a constant to convert gallons per minute, miles per hour, and feet to

gallons per acre

Where:

GPA = ______________________

GPM = ______________________

MPH = ______________________

SW = ______________________

gallons per acre

gallons per minute

miles per hour

swath width - feet

Measuring Ground Speed

Ground Speed - Miles Per Hour (MPH)

Where traveling 88 ft. in 60 seconds = 1 MPH

Doubling the ground speed reduces

the output by 1/2.

Speed(MPH)Distance(ft) x 60

Time(seconds) x 88

Hand Sprayer Calibration

Spraying to the point of runoff

• product added to each gal. or 100 gal.• uniform coverage-dripping from leaves• time and gallons per tree/1000 sq. ft.

“Dilute”

Technique important!!

Calibration ProcedureSteps:

– Mark off a calibration course of 1000 sq. ft.– Accurately measure the time required to spray

the calibration course using a proper technique. Remember only record the amount of time the gun is actually spraying.

– Measure the flow rate from the gun. Using the time recorded in step 2, spray into a calibrated container for that same length of time.

– Amount in the container represents the application rate per 1000 sq. ft.

Example:

It took 50 seconds for an applicator to spray the 1000 sq. ft. calibration course. The amount of spray collected from the gun in the 50 seconds was 1.4 gallons.

Hand Spray Guns: cont.

The application rate for this example is:

1.4 gallons per 1000 sq. ft.or

61 gallons per acre (43.56 x 1.4)

Nozzle Technology? How to use??• Nozzles designed to reduce drift• Improved drop size control• Emphasis on ‘Spray Quality’

Spray Characteristics are Important to Understand:

Demonstrates Turbo Flat vs TurboDrop-5 MPH Wind

NOZZLE TYPES:

FLAT SPRAY–Extended Range Flat-Fan–Turbo Flat-Fan–Drift Reduction Flat-Fan–Turbo Flood–Off center Flat-Fan

Others:Boomless

Handgun with disk & core or adjustable nozzle

Nozzles Types?

Is this tip good or bad?

Extended Range Flat-fan:• Tapered edge pattern• 80 and 110 degree fan• Requires overlap - 50 to 60%• 15-60 psi range

110°

80°

Nozzles Types?

Turbo Flat-fan: Turbulence chamber as in the Turbo Flood Tapered edge, wide angle flat pattern Designed to work in flat-fan nozzle holder Uniform spray distribution, 50-60% overlap Wide pressure range, 15 – 90 psi Large, drift resistant droplets Plastic with superior wear characteristics

TT

XR

Nozzles Types?

Air-Induction/Venturi NozzlesWhere air is drawn into the nozzle

cavity and exits with the fluid.

Air/Induction – Venturi Nozzle:• Greenleaf – TurboDrop• Air intake venturi section• Mixing Chamber - air and

spray solution blended• Pattern tip forms large air-

bubble drops• Exit tip flow 2X venturi orifice• Better Penetration?• Reduced run-off?• Improved coverage?• Adequate efficacy?• Reduced drift?

XR Flat-fan and Turbo Flat-fan compared to Venturi Style

5.0 MPH wind at 40 psi

XR vs TurboDrop Turbo Flat vs Turbo Drop

Off-Center Venturi Flat-fan

Boom Buster

Aerial Applications

 

The CP STRAIGHT STREAM NOZZLE

2. Set up for UniformityGoal is to put the material on evenly from nozzle to nozzle, end of boom to end of boom, and across the entire field.

20-inch spacing requires 17-19” above target for 50-60% overlap.

3. Coverage:

• Need knowledge of the product being used.– Systemic– Contact

• What is the target?– Soil– Grass– Broadleaf (smooth, hairy, waxy)– Leaf orientation – time of day

Origin Of Standardized Spray Droplet Size Categories

• 1985 -- British Crop Protection Council (BCPC)– Droplet size classifications, primarily designed

to enhance efficacy.– Uses the term SPRAY QUALITY for droplet

size categorie• 2000 -- ASAE Standard S572

– Droplet size classifications, primarily designed to control spray drift.

– Uses the term DROPLET SPECTRA CLASSIFICATION for droplet size categories.

4. Will affect drift:

• Movement of spray particles off-target.

• Creating smaller spray drops will result in increased drift.

• Is it Coverage vs Drift?

• What is the answer?$64,000 Question?

Why Interest in Drift?• Spotty pest control• Wasted chemicals• Off-target damage• More high value specialty crops• Urban sprawl and.....• Less tolerant neighbors• Litigious Society• More wind?? (Timing)• Environmental impact

– Water and Air Quality

• Public more aware of pesticideconcerns! (Negative) (Perceptions)

• Result-higher costs-$$$

Technical Aspects of Spray Drift

Definition of Drift

Movement of spray particles and vapors off-target causing less effective control and possible injury to susceptible vegetation, wildlife, and people.

Adapted from National Coalition on Drift Minimization 1997 as adopted from the AAPCO Pesticide Drift Enforcement Policy - March 1991

Types of Drift

Vapor Drift - associated with volatilization (gas, fumes)

Particle Drift - movement of spray particles during or after the spray application

Factors Affecting Drift

Spray Characteristics chemical formulation drop size evaporation

Equipment & Application nozzle type nozzle size nozzle pressure height of release

Weather air movement (direction and

velocity) temperature and humidity air stability/inversions topography

Wind Direction

• Wind direction is very important– Know the location of sensitive areas -

consider safe buffer zones.– Do not spray at any wind speed if it is blowing

towards sensitive areas - all nozzles can drift.– Spray when breeze is gentle, steady, and

blowing away from sensitive areas.– “Dead calm” conditions are never

recommended.

Under normal conditions air tends to rise and mix with the air above. Droplets will disperse and will usually not cause problems.

Normal Temperature Profile

Altitude

Cooler

Warmer

Temperature decreases with height

Increasing Temperature

Inversions

Under these conditionsthe temperature increases as you move upward. This prevents air from mixing with the air above it. This causes small suspended droplets to form a concentrated cloud which can move in unpredictable directions.

Temperature Inversion

Altitude

Temperature increases with height

Warm Air

Cool Air

Increasing Temperature

Temperature Inversions

Cloud of 5-25 u oil droplets generated under unstable conditions

105 foot temperature monitoring tower

8’ 41°F

16’ 41°F

32’ 40°F

64’ 40°F

105’ 38°F

8’ 33°F16’ 36°F32’ 37°F64’ 38°F

105’ 38°F

.5 mph wind

2.5 mph wind

Shallow surface inversionSTABLE conditions up to 64’ NEUTRAL conditions at 105’

Cloud is dispersing

Courtesy – George Ramsay, Dupont

Strategies to Reduce Drift:• Select nozzle to increase drop size• Increase flow rates - higher application volumes• Use lower pressures• Use lower spray (boom) heights• Avoid adverse weather conditions• Consider using buffer zones• Consider using new technologies:

– drift reduction nozzles– drift reduction additives– shields, electrostatics, air-assist

www.bae.ksu.edu/rewolf/

rewolf@ksu.eduThanks!