Pesticide Formulations and Application Equipment
This domain covers how products are formulated, how that changes handling and drift behavior, and how to calibrate a sprayer so the labeled rate actually reaches the target.
Formulations and what they change
- EC (emulsifiable concentrate): solvent-based, good coverage, higher phytotoxicity and drift risk, often strong signal words.
- WP / WDG (wettable powder, water-dispersible granule): requires agitation, can abrade nozzles and screens.
- SC or flowable: suspended particles; needs agitation but little solvent.
- SL (soluble liquid): dissolves in water; simple but prone to runoff on saturated soil.
- CS (capsule suspension), baits, granules, ULV, fumigants: controlled release or special handling; granules and baits reduce drift but need proper placement.
- Adjuvants: surfactants, crop oils, methylated seed oils, drift retardants, and water conditioners. Add them in the label's order; do a jar test for unfamiliar mixes.
Equipment and calibration
Nozzle type sets droplet size: flat fan for broadcast, even fan for banding, hollow cone for directed coverage, full cone for soil, air-induction for coarse drift-reducing droplets. Flow varies with the square root of pressure, so doubling pressure raises flow about 41 percent and pushes more fine droplets. Calibrate with the standard formula: GPA = (5940 × GPM per nozzle) ÷ (MPH × nozzle spacing in inches)
Worked example
A 200-gallon tank, 0.20 GPM nozzles on 20-inch spacing, at 5.0 MPH. GPA = (5940 × 0.20) ÷ (5 × 20) = 1188 ÷ 100 = 11.9 GPA. Acres per tank = 200 ÷ 11.9 = 16.8 acres. At a label rate of 1.5 pt/A, product needed = 16.8 × 1.5 = 25.2 pt = 3.15 gallons.
Traps
Changing speed after calibration (recalibrate). Mixing EC before dry formulations (follow the W-A-L-E-S order and label). Trusting a clogged or worn nozzle tip (check flow and replace matched sets). Adding a drift retardant as a substitute for correct boom height and wind judgment.