CORE Ch11 Study Guide: Pesticide Application Procedures

Learning Objectives

After studying this chapter, you should be able to:

Name different application procedures and equipment types.
Discuss safety systems (closed mixing/loading, enclosed cabs, containment).
Identify factors affecting calibration (nozzles, volumes, pressures, speeds).
Explain the importance of calibration.
Calculate application area.
Determine application rate and amount of concentrate/diluent needed.
Choose drift reduction practices.

Application Methods

Your choice depends on target pest, target site, pesticide properties, equipment, and cost.

Method

Description

Band

Parallel strips between or over rows of crops.

Basal

Herbicide directed to lower portions of brush or small trees.

Broadcast

Uniform application to an entire area or field.

Crack-and-Crevice

Small amounts in cracks of buildings (baseboards, cabinets).

Directed-Spray

Targets specific pests to minimize nontarget contact.

Foliar

Directed to leafy portions of plants.

Rope-Wick / Wiper

Pesticide wiped onto weeds taller than crop or selected plants.

Soil Application

On or in the soil rather than growing plant.

Soil Incorporation

Tillage, rainfall, or irrigation moves pesticide into soil.

Soil Injection

Under pressure beneath the soil surface.

Space Treatment

Pesticide applied in an enclosed area.

Spot Treatment

Small, distinct areas.

Tree Injection

Under the bark of trees.

Safety Systems

Benefits of closed systems: increase handler safety, reduce PPE burden, decrease spills, and give more accurate measurement of concentrate (reducing over- or underdosing).

Closed Mixing and Loading Systems

Prevent pesticides from contacting handlers during mix/load. Two primary types:

Mechanical systems — interconnected equipment uses gravity or suction to move concentrate from container to sprayer. Often custom-made. Commonly used with minibulk containers (40–330 gallons).
Water-soluble packaging — premeasured pesticide inside a water-soluble bag. The whole bag is placed unopened into the mix tank. Simple, but needs time to dissolve.

Enclosed Cabs

🎯 Trick Spot: An enclosed cab is considered a supplement to PPE — NOT a replacement. You still wear all label-required PPE inside the cab. Some ag use labels may allow exceptions, but the default rule is "all label PPE, always." Outside surfaces of cab and equipment are contaminated — wear PPE when getting in/out.

Pesticide Containment Systems (Pads)

Required when mixing/loading repeatedly at the same site (check EPA and state rules).
Permanent pads: impermeable material, concave or with curbs/berms/walls high enough to contain the largest spill, leak, or wash-water volume likely, plus a sump or pump system to recover released material.
Portable pads/trays (heavy-duty plastic) for mix/load at the application site.

Application Equipment Overview

Nearly 90% of pesticides are formulated for spraying. Equipment ranges from aerosol cans to power sprayers to aircraft.

Sprayer Types

Hydraulic (liquid) sprayer — water or liquid carrier; uses pump/gas pressure to atomize at nozzle.
Ultra-low-volume (ULV) — applies pesticide as formulated or with dramatically reduced carrier.
Manual sprayers — spot treatments, small areas. Inexpensive, simple.
Air-blast (mist) sprayer — uses water AND air as carriers; airstream delivers droplets. Used for fruit trees, vineyards, vegetables, Christmas trees.

Sprayer Components

Tank — non-corroding material, watertight cover, bottom drain opening, large top opening for filling/cleaning/inspection. Agitation system keeps mixes uniform (essential for WP and DF).
Pump — produces flow; must resist corrosion and abrasion. Never run dry or exceed manufacturer pressures. Depends on spray liquid for lubrication and cooling.
Nozzles — control amount applied, droplet size (coverage and drift), distribution and pattern.
Flow meters — measure nozzle flow rate and uniformity.

Nozzle Materials

Material

Use

Brass / Aluminum

Not for abrasive materials (WP, DF) — they wear too fast.

Plastic / Hardened Stainless Steel / Ceramic

Hard, wear-resistant — preferred for abrasive formulations.

⚠️ Exam Tip: A nozzle that produces primarily larger droplets minimizes drift. A nozzle that produces primarily smaller droplets maximizes coverage. Always replace worn nozzles — wear destroys pattern.

Granular Applicators

Gravity-feed with an adjustable opening.
Band applicators — hoses/tubes with deflectors; calibrate each unit separately.
Broadcast applicators — tubes/deflectors or spinner.
Rotary spreaders — distribute to front/sides by a spinning disk or fan.
Drop spreaders — sliding gate opens hopper holes; gravity feed. Superior to rotary when precise placement is required.
Rate is affected by ground speed, granule size/shape/density, terrain, humidity, and temperature.

🎯 Trick Spot: Drop spreaders are superior to rotary spreaders when precise placement is needed. Rotary spreads the granules broadly — great for coverage but not precision.

Other Equipment

Rubs, walk-through sprayers, dipping vats — animal pest control.
Bait dispensers — rodents, insects, predators.
Foggers — indoor and some outdoor insect control.
Chemigation systems — greenhouses and field crops.
Dusters — small-scale disease and insect work.

Equipment Calibration

Calibration = measuring and adjusting the amount of pesticide equipment applies to a specific area. Ensures the correct amount is applied uniformly. Charts are approximate — calibration is essential for every operator and condition.

Why Calibrate?

Too little pesticide = fails to control the pest.
Too much = illegal, damages the target, produces illegal crop residues, harms environment and non-target organisms.

Three Variables That Affect Boom Sprayer Output

Nozzle flow rate — depends on orifice size, nozzle pressure, spray liquid density.
Ground speed of the sprayer.
Width sprayed per nozzle.

Spray application rate varies INVERSELY with ground speed.
Doubling the speed REDUCES gallons/acre by half.
Doubling the effective width sprayed per nozzle also REDUCES the applied amount by half.

🎯 Trick Spot: Pressure cannot be used for major changes in application rate. Doubling the pressure does NOT double the flow rate. To double flow rate, you must increase pressure four times. Pressure is only for minor corrections (like compensating for nozzle wear).

Calculating Area — Three Formulas You Must Know

Rectangular

Area = length × width
Note: 1 acre = 43,560 sq. ft.

Example: 1,320 ft × 120 ft = 158,400 sq. ft. = 3.6 acres.

Triangular

Area = (base × height) ÷ 2

Example: base 325 ft × height 150 ft ÷ 2 = 24,375 sq. ft. = 0.6 acres.

Circular

Area = π × r² = 3.14 × r²
radius = ½ diameter

Example: 90-ft diameter → r = 45 ft → 3.14 × 45² = 6,358.5 sq. ft. = 0.15 acres.

⚠️ Exam Tip: Always convert between square feet and acres using 43,560 sq ft = 1 acre. For triangles, divide by 2. For circles, radius is half of diameter — squared, then times 3.14.

Calculating Application Rate

Use your calibration volume to scale up to the application area.

Example

Scenario: Calibration test used 10 gallons over 0.25 acre. Target: 10 acres. Label rate: 4 oz product per 1 gallon spray mix.

Step 1 — Total spray mix needed:
10 gal ÷ 0.25 acre = 40 gal/acre
40 × 10 acres = 400 gallons of spray mixture.

Step 2 — Product needed:
400 gal × 4 oz/gal = 1,600 oz of product.

Step 3 — Convert to gallons (128 oz = 1 gal):
1,600 oz ÷ 128 oz/gal = 12.5 gallons of product.

Common conversions:
128 fluid ounces = 1 gallon
1 acre = 43,560 square feet
Volume measures: liquids, some granulars
Weight measures: dusts, powders, most dry formulations

Techniques to Minimize Drift

Nozzle Choices

Select nozzles that give the largest droplet size that still provides adequate coverage.
Larger orifice = lower drift potential.
Air-induction (venturi) nozzles form larger droplets with an air-fluid mix and produce fewer fine particles. Require higher pressure (40–100 psi) but dramatically reduce drift.

Pressure & Speed

Exceeding recommended pressure range increases drift.
Use pressure for minor corrections only — doubling pressure only modestly increases flow.
With electronic rate controllers, doubling sprayer speed causes a fourfold pressure increase to maintain volume — creating serious drift potential.
Avoid high ground speeds and sudden speed changes.

Boom Height

Lower boom = less drift. Maintain a 1:1 ratio of boom height to nozzle spacing for proper overlap. Watch pattern uniformity.

Weather & Buffer Zones

Avoid high-wind applications.
Do not spray during a temperature inversion.
Leave buffer zones near sensitive areas.

Drift-Control Additives

🎯 Trick Spot: Drift-control additives can reduce downwind drift by 50–80%, but some actually increase drift. Test carefully. They may also reduce coverage and overall effectiveness. Never rely on additives alone — combine with good nozzle choice, proper pressure/speed, and boom height.

Air-Blast Sprayers

Minimize spraying over the canopy top. Use the minimum airspeed giving good penetration. Consider tower sprayers.

⚠️ Exam Tip: The best drift-reduction program combines many techniques — nozzle choice, low pressure, low boom, appropriate speed, weather awareness, buffer zones, and (cautiously) additives. No single practice is enough.

Key Terms Cheat Sheet

Application methods: Band, basal, broadcast, crack-and-crevice, directed-spray, foliar, rope-wick/wiper, soil, soil incorporation, soil injection, space, spot, tree injection.

Closed Mixing/Loading System: Mechanical or water-soluble bags. Reduces exposure and PPE burden.

Minibulk container: 40–330 gallons. Often returned for refilling.

Enclosed Cab: Supplement to PPE — NOT a replacement. Still wear label PPE inside.

Containment Pad: Impermeable pad with curbs/berms to contain spills. Hold largest likely spill. Sump or pump recovery required for permanent pads.

Hydraulic sprayer: Water-based liquid carrier. ~90% of pesticides are sprayed.

Air-blast sprayer: Water + air carrier; used for orchards, vineyards, vegetables.

ULV (Ultra-Low-Volume): Applies pesticide as formulated or with very little carrier.

Nozzle Materials: Brass/aluminum wear fast with abrasives. Use plastic, hardened stainless steel, or ceramic for WP/DF.

Larger droplets: Less drift. Smaller droplets: More coverage.

Rotary spreader: Spinning disk/fan — broad distribution.

Drop spreader: Gravity through gate — superior for precise placement.

Calibration: Measuring/adjusting equipment to deliver the correct amount uniformly.

3 Boom Sprayer Variables: Nozzle flow rate, ground speed, width sprayed per nozzle.

Pressure rule: Double the pressure = only modest flow increase. Quadruple pressure to double flow. Don''t use pressure to change rate — only for minor corrections.

Speed rule: Rate varies INVERSELY with ground speed. Double speed = half rate.

Area formulas: Rectangle = L × W. Triangle = (b × h) ÷ 2. Circle = 3.14 × r². 43,560 sq ft = 1 acre. 128 fl oz = 1 gal.

Air-induction / Venturi nozzles: Form larger droplets, dramatically reduce drift, require 40–100 psi.

Boom height:boom spacing ratio: 1:1 satisfies most overlap requirements.

Drift additives: Can reduce drift 50–80% — or increase it if wrong. Not a replacement for good practices.

Chapter 11 — Pesticide Application Procedures