ultra-low pressure herbicide dispenser reduces drift and increases target adhesion

New Ultra-Low Pressure Herbicide Dispenser Reduces Drift

and Increases Target Adhesion

John LampeGreen Shoots, LLCOctober 18, 2016

Upper Midwest Invasive Species ConferenceLa Crosse, Wisconsin

Most herbicide spray equipment technology has been adapted from agriculture.

However, translating this spray model, to . . .

. . . this context is challenging.

For native area management

“Transfer efficiency” is key:

1. Hit just the target weed.

2. Keep the herbicide on the weed.

Foam Herbicide Technology

One way to increase transfer efficiency.

Foam herbicide . . . 1 Year Later.

Foam herbicide . . . 12 days later.

Ultra-Low Pressure Technology

A second way to increase transfer efficiency.

No-PumpPower Pack

On-off switch

Pressure Adjustment

Hose swivel

ChargerPort

No-Drip Wand

1, 2, or 3 gal. size

Ultra-Low Pressure Electric Dispenser

Electric Dispenser Backpack Frame

PaddedHip Belt

Molded, foam back pad

Molded plastic frame

Padded Shoulder Straps

Ultra-low pressure dispenser (con.)

• Precision pressure control: 0.2 psi increments.

• Ultra-low pressure range: 1.5 psi to 13 psi.

– Foam works best from: 1.5 to 10 psi.

– Foliar spray works best from: 5 to 13 psi.

– Basal spray works best below 5 psi.

No-Pump Power Pack

Why ultra-low pressure?

Need to step back a bit.

Dominant ModelHigh Pressure Spray

high pressure

Smaller spray drops

Leaf

High Pressure Spray Model

Drift

Justification:

Small Drops = Better Coverage

Air Induction Spray Model

high pressure

Bigger, slower spray drops

LeafLowerDrift

Air Induction Spray Model

introduce air

Justification:

Bigger, Slower Drops = Comparable Coverage + Less Drift

Why Are Bigger, Slower Drops Desirable?

• Big drops maintain flight direction better.

• Slow drops break apart less during flight.

• Note: Drops cannot be “so big” that the drops splatter and drip when hitting leaf surface.

Ultra-low pressure spray model:

ultra-low pressure

Bigger, slower spray drops

LowerDrift

Ultra-Low PressureSpray Model

Leaf

Justification:

Why not start with ultra-low pressure to create bigger, slower drops?

This case study is intended to test that assumption.

What Is Effect of Ultra-Low Pressure on:

1. Drop size?o I.e., are drops bigger?

2. The spray band?o I.e., are drops staying within the spray band?

3. Leaf adhesion and coverage?o I.e., are drops adhering to and providing good

coverage on foliage?

Caveat

• Case study

• intended to spark questions and reassessment.

10 in.

White paper

Indoor Spray Tests

No Wind!

Spray wand

Rail maintains wand height

White paper

Indoor Spray Tests

Walking Direction

Primary SprayBand

Centerline

Spray Setup

• Sprayer: traditional tank sprayer• Nozzle tip: Hypro® 30 HCX8 (hollow cone)• Solution: Water with colorant• Pressure levels:

o 9 psio 11 psio 15 psio 20 psio 30 psi

Comment on Nozzle Tip

• Tested many different nozzles.

• Found the Hypro® 30HCX8 (hollow cone) worked well at ultra-low pressure for spot spraying.

• (Consider, e.g., flat fan for broadcast spraying.)

• Counterintuitive: this is a hollow-cone nozzle rated for 40 to 150 psi!

9 psi 30 psi

Side-by-Side Comparison of Two Spray Bands

3 in. 7 in.

9 psi 30 psi

1. Drop size?o Ultra-low pressure increases drop size.

2. The spray band?

3. Leaf adhesion and coverage?


To answer 2nd question, we used same indoor test information.

Spray Setup

• Sprayer: traditional tank sprayer• Nozzle tip: Hypro® 30 HCX8 (hollow cone)• Solution: Water with colorant• Pressure levels:

o 9 psio 11 psio 15 psio 20 psio 30 psi

Measurement of “Shadow” Spray Band

Remember:No Wind!

Primary SprayBand

“Shadow” SprayBand

10 in.

20 in.

30 in.

Centerline

9 psi 30 psi

Side-by-Side Comparison of Two Spray Sheets

3 in. 7 in.

9 psi 30 psi8.5 inches from primary spray band edge

6.5 inches from primary spray band edge

Observations

At 15 inches from centerline:

o 9 psi – shadow spray band appears to end.

o 30 psi – shadow spray band still pronounced.

9 psi

30 psi How far beyond 30 in. does shadow band extend?

1.5 in.

15 in.

3.5 in.

>30 in.


2. The spray band?o Ultra-low pressure shrinks:

o primary spray band; ando shadow spray band.

3. Leaf adhesion and coverage?


Field Tests – Sept. 30, 2016

• Activity: Spot spraying of weeds such as buckthorn

• PSI: 3, 5, 8, 10, 15, 20, 25, and 30.

• Evidence: Photographs of foliage

Field Tests – Sept. 30 (con.)

• 1st Spray Solution:o 4.3% a.i. aquatic glyphosate (max label rate)o Colorant

• 2nd Spray Solution:o 4.3% a.i. aquatic glyphosate (max label rate)o Coloranto 0.5% a.i. surfactant (alkyl polyglucoside) (no anti-

foam)

Following Photos

• Highlight applications at 5, 10, and 30 psi.

5 PSI – No surfactant

30 PSI – no surfactant

5 PSI – with surfactant

5 PSI – With surfactant

Conclusions:


2. The spray band?o Ultra-low pressure shrinks:

o primary spray band; ando shadow spray band.

3. Leaf adhesion and coverage?o With surfactant – ultra-low pressure appears to

provide coverage comparable to high pressure.

Follow-Up Studies

• Comments, criticisms, and suggestions are appreciated.

• We’ll be studying ultra-low pressure dispensing over the next few years.

79

John Lampe:

• Email: [email protected]

• Cellphone: 651-245-4682

• Website: www.greenshootsonline.com

ultra-low pressure herbicide dispenser reduces drift and increases target adhesion

Environment