Environmental Protection, Drift, and Groundwater
Keep it on target and out of water
Environmental questions test your understanding of where pesticides go after application. Drift is movement off-target through the air (spray drift) or as vapor (volatilization). It is driven by droplet size, wind speed, boom height, temperature, humidity, and formulation (EC products are more volatile). Reduce drift with low-drift nozzles, lower pressure, larger droplets, correct boom height, and avoiding applications when wind is too high or air is calm/inverted. Temperature inversion is a classic trap: air is still at the surface with warmer air above, so fine droplets hang and travel long distances.
Groundwater and surface water contamination occur through leaching, runoff, and spills. Factors that increase leaching: high water solubility, low soil adsorption, persistence, sandy soils, shallow water tables, and heavy rain after application. Know buffer zones and setback distances on labels, and the concept of a mixing/loading pad to contain spills. Understand how pesticides affect pollinators (apply when bees are not foraging, follow label pollinator warnings) and aquatic life (respect aquatic setbacks).
Trap: questions that say "apply when wind is calm" - very calm conditions with an inversion are among the worst drift situations. Another trap: assuming a product is safe near water because it is "low toxicity" - the label's aquatic restrictions still apply.
Rule of thumb: if you see dust or smoke hanging near the ground or drifting sideways, an inversion exists - do not spray.