Ch.14: Application Methods and Equipment

2. Hydraulic Sprayers

• Hydraulic (liquid) sprayers are the most common, widely used type.
• Water is the most frequently used carrier (the liquid the pesticide is diluted in); sometimes liquid fertilizers or oils.
• Basic principle: pressure (from a mechanical pump or compressed air) forces the spray mix to a delivery device — a spray gun, wand, or boom.
• Spray droplets are formed by system pressure + the nozzle type + the orifice (opening) size.

Four basic parts: tank, screens, pump, nozzles.

• Tank — holds the spray mix. Agitation produces a uniform mixture and even application, especially for wettable powders or dry flowables. (Large bottom opening = drain/clean; large top opening = fill/clean/inspect.)
• Screens — filter grit and debris from the water line and nozzles; clean regularly.
• Pump — produces spray flow and agitation. Parts must resist corrosion and abrasion (wettable powders wear them). Never run above the manufacturer's recommended speed/pressure. Pumps rely on the spray liquid for lubrication and to prevent overheating.

3. Nozzles

• No single nozzle type is best for all applications (some work over a range).
• The nozzle tip determines: flow rate, volume applied, droplet size and pattern, uniformity, coverage, and drift potential.
• Nozzles are classified by the spray pattern they produce; the orifice size affects droplet size and flow rate.
• The pesticide label is the most important source for choosing a nozzle. If a label requires a medium or coarse spray, you must configure nozzle type, size, and pressure to produce it — doing otherwise is a label violation.
• Also weigh application rate, spray pressure, and travel speed, plus pesticide type and mode of action. Wettable powders/suspensions are prone to clogging.

Droplet size

• Droplet size strongly influences coverage and drift.
• Smaller droplets → more thorough coverage → essential for insecticides and fungicides.
• Larger/coarse droplets → less drift → used for weeds/herbicides. (Label example: coarse spray of 400 microns or more to avoid herbicide drift.)

4. Granular Applicators

• Product is applied in solid, granular form — not mixed with a liquid.
• Usually operate by gravity feed with an adjustable opening to regulate flow; available for band or broadcast.
• Rotary spreaders fling granules to the front and sides (spinning disk/fan).
• Drop spreaders release granules straight down through holes opened by a sliding gate in the bottom of the hopper — and give more precise placement than rotary.

5. Application Methods (Table 14.1)

6. Maintenance & Cleaning

• Benefits: prevents breakdowns, extends lifespan, cuts repair costs, ensures the proper rate, and gives effective control.
• Clean after each use; complete check at the beginning and end of each season.
• Cleaning avoids cross-contamination when switching products (residue can harm plants or cause incompatibility).
• Thoroughly clean inside and out before switching pesticides, before maintenance/repair, and before storage.
• Never let contaminated cleaning water reach surface or groundwater.
• Wear PPE when checking, using, and cleaning — surfaces and splashes carry residue.
• Inspect hoses, connectors, hopper/tanks, pumps, screens, and all moving parts. The label and manufacturer info are the best source for cleaning techniques.

Key Vocabulary