Pesticides & the Environment

When making a liquid spray application, which change makes the spray droplets MORE likely to drift off-target?

• Using larger spray droplets
• Spraying only when the wind is calm (under about 10 mph)
• Lowering the spray boom closer to the target
• Increasing the spray pressure, which produces smaller droplets ✓

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Pesticide 'runoff' that can contaminate surface water happens when:

• Pesticide vapors drift downwind onto a neighboring property
• Water from rain or irrigation carries the pesticide across the soil surface into streams, rivers, or other surface water ✓
• Sunlight breaks the pesticide down into new chemicals
• The pesticide binds to soil particles and stays in place

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A pesticide with a LONG half-life is one that:

• Breaks down slowly, so it persists in the environment longer and can build up with repeated applications ✓
• Breaks down within a few hours of application
• Is automatically classified as a restricted-use pesticide
• Cannot dissolve in water under any conditions

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Applying a broad-spectrum, residual insecticide can sometimes trigger a secondary pest outbreak (for example, a spider-mite flare-up). The main reason is that the insecticide also:

• Increases the target pest's resistance overnight
• Raises the soil pH enough to favor mites
• Makes the treated plants more nutritious to pests
• Kills the natural enemies (predators and parasites) that had been keeping the secondary pest in check ✓

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Which property makes a pesticide MORE likely to leach down through the soil and contaminate groundwater?

• It dissolves easily in water and breaks down slowly in the environment ✓
• It binds tightly to soil particles
• It evaporates quickly after application
• It has a very short half-life

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