10.1 Application Equipment, Components & Maintenance

10.1 Application Equipment, Components & Maintenance

Effective and legally compliant pesticide stewardship requires selecting, operating, and maintaining application equipment that delivers chemical formulations precisely to the biological target. Applying pesticides with faulty, corroded, or poorly maintained equipment leads to non-target drift, groundwater leaching, surface runoff, severe crop phytotoxicity, and compromised pest suppression. Pesticide applicators in New Hampshire must understand the mechanical anatomy, fluid dynamics, and operational limitations of both liquid hydraulic sprayers and granular application systems.

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Primary Application Equipment Categories

Pesticide application systems vary widely depending on the target site, treatment scale, crop canopy density, and formulation type.

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|                   PRIMARY APPLICATION EQUIPMENT CATEGORIES              |
+-------------------------------------------------------------------------+
| 1. HYDRAULIC SPRAYERS                                                   |
|    - Uses water or liquid carrier under pressure through nozzles        |
|    - Low-pressure boom sprayers (turf, field crops, rights-of-way)      |
|    - High-pressure handgun/skid units (shade trees, structural perimeters|
|    - Backpack / hand-wand sprayers (spot treatments, sensitive borders) |
|                                                                         |
| 2. AIR-BLAST SPRAYERS (MIST BLOWERS)                                    |
|    - High-velocity fan airstream carries atomized droplets              |
|    - Standard for orchard tree fruit, high-bush blueberries, vineyards  |
|    - High canopy penetration; elevated drift hazard if mismanaged       |
|                                                                         |
| 3. GRANULAR SPREADERS                                                   |
|    - Distributes dry formulated pellets, granules, or bait matrices     |
|    - Drop spreaders: gravity drop between wheels, precise boundaries    |
|    - Rotary / Centrifugal spreaders: spinning impeller, wide swaths     |
|                                                                         |
| 4. CHEMIGATION SYSTEMS                                                  |
|    - Injects pesticide into irrigation lines (overhead, center pivot)   |
|    - Requires mandatory anti-siphon backflow preventers to protect water|
|                                                                         |
| 5. ULTRA-LOW VOLUME (ULV) FOGGERS                                       |
|    - Generates aerosol mists (<30 microns) for mosquito adulticiding    |
|    - Specialized for public health vector control and greenhouse spaces |
+-------------------------------------------------------------------------+

1. Hydraulic Sprayers

Hydraulic sprayers utilize liquid pressure generated by a mechanical pump to atomize the spray mixture through hydraulic nozzles into droplets. They represent the most common category of pesticide machinery.

• Low-Pressure Boom Sprayers: Operate between 20 and 60 pounds per square inch (PSI) with horizontal booms spanning 10 to 60 feet. Commonly deployed on commercial turf, golf courses, agricultural row crops, and roadside rights-of-way. They provide uniform broadcast coverage with relatively coarse, drift-resistant droplets.
• Backpack and Hand-Wand Sprayers: Self-contained units carrying 2 to 5 gallons of spray mixture pressurized via a hand-operated piston or diaphragm lever, or an onboard rechargeable 18V lithium-ion battery. They are indispensable for spot treatments, noxious weed control in rocky New Hampshire pastures, and foundation perimeter applications.
• High-Pressure Handgun / Skid Sprayers: Capable of generating 200 to 800 PSI, delivering 10 to 60 gallons per minute (GPM) through heavy-duty hoses and adjustable spray guns. Used primarily for penetrating tall shade tree canopies, dense ornamental plantings, and structural wood-destroying organism injections.

2. Air-Blast Sprayers (Mist Blowers)

Air-blast sprayers combine hydraulic pressure with a powerful axial or centrifugal fan that generates an air blast moving between 80 and 150 miles per hour. The high-velocity airstream displaces ambient air inside tree canopies, turns foliage leaves over, and deposits fine spray mist onto both upper and lower leaf surfaces.

• Key Applications: Heavily utilized in New Hampshire apple orchards, stone fruit blocks, commercial vineyards, and high-bush blueberry plantings.
• Operational Hazard: Because air-blast sprayers generate fine droplets propelled into ambient air currents, they present an elevated risk of airborne drift and thermal inversion transport. Applicators must calibrate air deflectors, turn off top nozzles when spraying perimeter border rows, and avoid spraying when wind conditions exceed 10 miles per hour.

3. Granular Spreaders

Granular equipment meters and deposits dry, ready-to-use chemical formulations (granular herbicides, pre-emergents, granular insecticides, and fertilizer-pesticide combinations).

• Drop Spreaders: Rely purely on gravity. Granules flow through an adjustable metered orifice gate at the base of the hopper and fall directly to the soil between the wheels. Drop spreaders provide sharp edge definition with virtually zero drift hazard, making them ideal for treating turf immediately adjacent to ornamental flower beds, sidewalks, or surface water buffers. However, any gap in wheel tracks leaves an untreated strip, while overlapping tracks creates severe chemical streaking.
• Rotary (Centrifugal) Spreaders: Granules drop onto a spinning horizontal impeller disc that slings the particles in a wide semi-circular arc (typically 6 to 18 feet wide). Rotary spreaders cover expansive acreage quickly. However, the distribution pattern is tapered (heavier near the center and lighter at the perimeter), requiring a 30% to 50% swath overlap. Rotary spreaders are highly susceptible to wind deflection and can deposit granules errantly onto non-target impervious surfaces (sidewalks and driveways), requiring immediate post-application sweeping under Pes 500 rules.

4. Chemigation Systems

Chemigation is the application of agricultural pesticides through irrigation systems (such as overhead center pivots, traveling guns, or solid-set sprinkler lines).

• Environmental Safeguards: Because chemigation directly connects pesticide lines to irrigation supply water, strict federal and state laws govern installation. The system must incorporate a certified anti-siphon backflow preventer, an automatic low-pressure drain, an interlocking power cutoff switch between the chemical injection pump and the irrigation water pump, and a vacuum relief valve to prevent chemical back-siphoning into groundwater wells or farm ponds.

5. Ultra-Low Volume (ULV) Foggers

ULV equipment atomizes concentrated pesticide formulations without water dilution into extremely fine aerosol droplets (volume median diameter between 5 and 30 microns). ULV cold foggers and thermal generators are specialized almost exclusively for public health vector management (adult mosquito and blackfly control by municipal mosquito control districts) or structural crack-and-crevice treatments in commercial warehouses.

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Core Components of a Liquid Hydraulic Sprayer

A commercial hydraulic sprayer represents an interconnected closed-loop plumbing network. Each component must function properly to deliver uniform chemical rates.

1. Spray Tanks

Sprayer tanks must resist chemical corrosion, physical impact, and ultraviolet radiation, while featuring a sloped bottom or deep drain sump for complete drainage.

• Polyethylene Tanks: Extremely popular, lightweight, corrosion-proof, and translucent (allowing visual monitoring of liquid levels). However, they cannot be easily welded or repaired if cracked and can degrade under prolonged ultraviolet sunlight exposure if left outdoors.
• Fiberglass Tanks: Highly resistant to corrosive chemicals and agricultural acids. Can be patched and repaired in the field with resin kits, but are brittle and subject to cracking from severe physical shock.
• Stainless Steel Tanks: The most durable, chemically inert, and long-lasting tank construction. Handles virtually all solvent-based and corrosive formulations. They are heavy and carry the highest initial purchase cost.

2. Agitation Systems

Pesticide formulations—especially wettable powders (WP), water-dispersible granules (WDG), and dry flowables (DF)—are physical suspensions rather than true solutions. If tank agitation fails, suspended particles settle to the bottom within minutes, causing extremely concentrated toxic doses at the start of a spray pass and ineffective, diluted water at the end.

• Mechanical Agitation: Employs a steel shaft running through the lower third of the tank equipped with rotating paddles or propellers driven by the tractor PTO or hydraulic motor. Mechanical agitation provides violent, positive mixing and is the gold standard for heavy wettable powder suspensions and thick slurry mixtures.
• Hydraulic Jet Agitation: Diverts a portion of the pump's high-pressure output back into the tank through specialized venturi jet aspirators located along the tank floor. To maintain adequate suspension, hydraulic agitation systems must dedicate at least 5% to 10% of total pump capacity (typically 3 to 6 GPM for small tanks, 10 to 20 GPM for large agricultural tanks) continuously to the agitation line.

3. Sprayer Pump Selection and Fluid Mechanics

The pump is the circulatory engine of the hydraulic sprayer, lifting liquid from the tank, pressurizing the manifold, feeding agitation jets, and forcing fluid through nozzle orifices.

• Roller Pumps: Feature a slotted rotor carrying flexible synthetic rollers (nylon, Teflon, or Buna-N rubber) rotating inside an eccentric housing. While compact, self-priming, and economical, abrasive suspensions score the housing and ruin the rollers quickly.
• Centrifugal Pumps: Utilize a rapidly rotating impeller (3,000 to 4,500 RPM) to throw liquid outward by centrifugal force. They are non-positive displacement pumps, generate immense flow volumes, handle abrasive wettable powders effortlessly, and require no pressure relief valve. However, they generate low to moderate pressures (rarely exceeding 70 PSI) and are not self-priming, requiring mounting below the tank.
• Diaphragm Pumps: Positive displacement pumps utilizing elastomeric rubber or Viton diaphragms reciprocating via a crankshaft. Because the spray solution contacts only the corrosion-proof housing and synthetic diaphragm—never contacting internal mechanical gears or lubricating oil—diaphragm pumps provide outstanding longevity when spraying abrasive slurries at pressures up to 700 PSI.
• Piston Pumps: Positive displacement pumps using one or more pistons moving back and forth within precision cylinders. Capable of generating tremendous operating pressures (up to 1,000 PSI) for high-pressure handguns spraying 60-foot oak trees. Piston pumps produce distinct pressure pulses and require an inline surge tank or pulsation damper.

4. Pressure Regulators, Relief Valves & Dampened Gauges

• Pressure Regulator: Regulates the operating pressure delivered to the boom manifold. By adjusting the spring-loaded bypass valve, excess fluid from the pump is diverted through the return line back into the spray tank, establishing precise system operating pressure.
• Pressure Relief Valve: A spring-loaded safety valve on positive displacement systems (piston, roller, diaphragm) that opens automatically when manifold valves are shut off, preventing burst hoses, damaged fittings, or catastrophic pump housing rupture.
• Pressure Gauge: The operator's primary monitoring instrument. Must be accurate, liquid-filled (glycerin or silicone-dampened) to absorb severe mechanical pulsation, and matched to operating pressures (the normal operating range should occupy the middle third of the gauge face, e.g., a 0–100 PSI gauge for a 30–50 PSI turf boom).

5. Strainers and the Staged Filtration Hierarchy

To safeguard precision pump impellers and prevent clogged nozzle tips in the field, sprayers must utilize a staged series of strainers with progressively smaller mesh sizes:

1. Tank Opening Strainer Basket (16 to 30 mesh): Catches large debris, leaf litter, and chemical packaging fragments when filling the tank.
2. Suction-Line / Intake Strainer (50-mesh): Installed between the tank shut-off valve and the pump inlet. Prevents coarse abrasive sand and undissolved chemical lumps from entering and damaging the pump.
3. Pressure-Line Filter (50 to 100 mesh): Installed downstream of the pump and pressure regulator before liquid reaches the boom manifold, trapping microscopic particulates.
4. Nozzle Tip Strainers (50 to 100 mesh): Individual screens positioned directly inside each nozzle body immediately behind the nozzle orifice. Nozzle bodies frequently incorporate check valves that snap shut when system pressure drops below 5 to 10 PSI, eliminating nozzle dripping when the boom is switched off.

6. Plumbing and Hoses

Hoses must be constructed from synthetic chemical-resistant polymers (EPDM, polyurethane, or reinforced PVC). Suction hoses must be wire-reinforced or rigid non-collapsible ribbed construction to prevent vacuum collapse under pump suction. Working pressure ratings for pressure hoses must exceed maximum potential pump surge pressure by at least two-fold (e.g., a 200 PSI working pressure rating for a system operating at 60 PSI).

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Routine Maintenance, Cleaning, Winterization & Inspection

Systematic equipment maintenance preserves machinery value, ensures application accuracy, and prevents hazardous chemical spills:

Daily Operating Inspection

• Inspect all hoses for soft spots, bulges, cracking, weeping, or mechanical abrasion from frame contact.
• Examine fittings, clamps, and boom shutoff valves for active leaks.
• Check nozzle spray patterns for streaking, fogging, or uneven spray fans while spraying clean water.
• Verify that operating pressure matches target calibration values without fluctuating needle flutter.

Decontamination and Chemical Flush Protocols

Leaving pesticide mixtures in a spray tank overnight causes chemical precipitation, gummed-up check valves, corrosion of brass and aluminum components, and cross-crop phytotoxicity when switching products. The system must be flushed thoroughly after each day of use:

1. Empty the spray tank completely on an approved labeled application site.
2. Add clean water equal to 10% to 20% of tank capacity, circulate through agitation and boom lines, and spray out on a labeled site.
3. For stubborn systemic herbicides (such as sulfonylureas or growth regulators like 2,4-D and dicamba), fill the tank with water and add a certified commercial tank decontaminant or household ammonia (1 quart per 25 gallons of water). Agitate, let sit overnight, and flush through all boom plumbing.
4. Remove all nozzle tips, strainers, and filter screens. Scrub them gently with clean water and a soft nylon-bristle brush (never a pocket knife, wire, or pin, which ruins precision tip orifices).

Winterization Protocol (New Hampshire Cold-Climate Care)

New Hampshire freezing winter temperatures will rupture water-filled pumps, crack pressure gauges, split boom pipes, and destroy control valves. Winterization requires complete fluid displacement:

• Drain all tanks, pump sumps, line filters, and boom drops.
• Introduce 2 to 5 gallons of non-toxic RV propylene glycol antifreeze (never use toxic automotive ethylene glycol).
• Engage the pump at low throttle to circulate the antifreeze through all bypass lines, agitation circuits, pressure regulators, boom manifolds, and nozzle bodies until colored antifreeze discharges from every tip.
• Seal all openings to prevent rodent entry during off-season winter storage.

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Container Rinsing & Disposal Standards

Empty, unrinsed pesticide containers retain significant chemical residues and are classified as hazardous waste. Federal FIFRA mandates and New Hampshire administrative regulations require immediate rinsing of all empty containers upon emptying:

1. The Triple-Rinse Procedure

1. Allow the empty container to drain into the active spray tank for at least 30 seconds until individual drips cease.
2. Fill the container one-fourth (25%) full of clean water.
3. Secure the container cap tightly and shake vigorously for 30 seconds, rotating the container to wash all interior walls.
4. Pour the rinsate directly into the active spray mix tank, draining for 30 seconds.
5. Repeat this procedure two more times (for a total of three rinse cycles).

2. The Pressure-Rinse Procedure

1. Allow the container to drain into the spray tank for 30 seconds.
2. Insert a specialized sharp probe-type pressure rinsing nozzle through the side or bottom of the inverted container.
3. Flush with clean water at 40 PSI or higher for a minimum of 30 seconds, directing rinsate directly into the spray tank.

Once triple-rinsed or pressure-rinsed, the container is legally classified as non-hazardous solid waste. The applicator must puncture the container top and bottom to prevent reuse, and deliver it to an approved agricultural plastics recycling facility or sanitary municipal landfill.