Which two factors are most important in avoiding vapor drift?

• A. Temperature and pesticide volatility
• B. Wind speed and soil type
• C. Humidity and crop height
• D. pH and rainfall

Answer: (A)

Vapor drift comes down to how much of the pesticide becomes vapor and how quickly that vapor forms in the air. The two factors that matter most are temperature and the pesticide’s volatility. Higher temperatures give molecules more energy to escape from liquid into vapor, increasing the amount of vapor that can travel with air currents. A pesticide with high volatility will vaporize more readily than a less volatile one, so it’s more prone to drifting even under mild conditions. By choosing products with lower volatility and applying under cooler conditions, you reduce the amount of vapor that can move off-target. Other factors like wind, humidity, or crop height can influence drift in other ways, but for vapor drift specifically, temperature and volatility are the key drivers.