Pesticide applicators should consider the following whenever using pesticides:
- Learn where sensitive crops are located in relationship to your application site. Always be aware of what is downwind of your application site.
- Measure and record weather conditions.
- Measure wind speed and direction before, during, and after the application. Always follow label information, but generally, windspeeds of 3 to 10 mph are preferable. On a calm day with no wind, a temperature inversion (trapped layer of air) could result in the horizontal movement of pesticides. This is more common in early mornings and evenings.
- Keep track of temperature and relative humidity. High temperatures and low relative humidity leads to more evaporation of pesticides. These smaller droplets can be transported large distances.
- Modify your application techniques, following requirements and recommendations on the pesticide label.
- Reduce spray pressure to produce larger spray droplets, as these are less likely to drift.
- Use low-drift nozzles, such as those with air-induction technology. Replace all worn nozzles.
- Keep the spray boom as low as possible while allowing good coverage and penetration. Boom shields and windscreens may help reduce drift by directing the application and reducing wind effect.
- Include a drift control agent in the spray tank.
- More information here.
Herbicide Stewardship and Drift Prevention
- Avoid applying near crops in sensitive stages (flowering, leaf emergence)
- Check the Driftwatch site for sensitive crops near application area
- Map surrounding sensitive crops and communicate with neighbors. Check weather forecasts for wind direction and speed, temperature, and rain
- Avoid applying pesticides with volatile active ingredients during hot afternoons
- Watch for and avoid applying during inversions (no wind)
Application Method and Technique
- Boom height is critical: a lower boom reduces drift
- Application speed: slower is better
- Keep equipment calibrated and clean
- Nozzle choice: use low drift types
- Air induction nozzles: 4-10x fine particle reduction
- Use spray pressure recommended for nozzle and by label
- Check the pesticide label for susceptible crops to avoid
- Trees, gardens, ornamentals may be susceptible
- Use Crop Calendar and Sensitive Crop Maps
- Check wind direction leaving target
- Low humidity will evaporate small droplets
- Temperature affects droplet size and product volatility
- Inversions have potential to keep fine particles together
- Use your weather station information to plan applications
(Provided as a service by the Industry Task Force II on 2, 4-D Research Data.)