What should be considered a risk when applying pesticides during temperature inversions?

• A. Inversions can cause significant long-distance drift
• B. Inversions prevent drift
• C. Inversions have no effect on drift
• D. Inversions only affect drift at night

Answer: (A)

Temperature inversions create a stable layer of air near the ground with very little vertical mixing. When pesticides are applied under these conditions, the droplets don’t rise and disperse as they normally would. Instead, the stable layer traps the spray near the surface and the droplets can be carried horizontally by even light winds, staying suspended longer and traveling far from the application site. This makes drift a real and important risk, because off-target deposition can affect nearby crops, water sources, or non-target organisms. Inversions commonly form in the early morning or evening under clear skies and calm conditions, so it’s essential to check for these conditions and postpone spraying if an inversion is present or likely.