How should you document weather conditions at the time of application, and why is it important?

• A. Record wind speed and direction, temperature, humidity, and possibly precipitation; weather affects drift, evaporation, and efficacy and is required for compliance
• B. Record only temperature
• C. Record soil moisture and cloud type
• D. Do not record any weather data

Answer: (A)

Weather conditions at application time impact how well the pesticide works and how likely it is to drift to unintended areas. Recording wind speed and direction, temperature, humidity, and any precipitation creates a record of the factors that influence drift, evaporation, and efficacy, and it also helps show compliance with label requirements.

Wind speed and direction are critical because they determine how far and where droplets or dust may travel. Many labels specify a safe wind speed range for application, and documenting it helps prove you stayed within those limits. Temperature affects volatility and how quickly the product dries or adheres to surfaces, while humidity influences droplet evaporation and deposition on targets. Precipitation matters because rain or significant moisture after application can wash off the product, affect performance, and trigger re-entry or re-application intervals on the label.

Having this weather information provides context for the results you see, supports sound decision-making during future applications, and serves as a compliance record if questions arise. Recording only temperature misses the key factors that drive drift and performance, and focusing on soil moisture, cloud type, or avoiding weather data altogether would not give a complete, actionable picture.