Herbicide Stewardship and Drift Prevention

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Consider the following whenever using pesticides:

1. Learn where sensitive crops are located in relationship to your application site. Always be aware of what is downwind of your application site.
2. Measure and record weather conditions.
   • Measure wind speed and direction before, during, and after the application. Always follow label information, but generally, wind speeds between 3 and 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 vapors can travel long distances.
3. 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.
   • Read more about managing drift.
   • Thoroughly clean application equipment after use to avoid contaminating future tank loads with leftover pesticide residue.

Herbicide Stewardship and Drift Prevention

Plan Ahead

• Avoid applying near crops in sensitive growth stages (flowering, leaf emergence).
• Check the DriftWatch site for sensitive crops near the 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 temperature inversions and avoid applying during them.

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.

Off-Target Vegetation

• Check the pesticide label for susceptible crops to avoid.
• Trees, gardens, and ornamentals may be susceptible.
  Read about herbicide damage to trees from the Nebraska Forest Service.
• Use Crop Calendar and Sensitive Crop Maps.

Climate Conditions

• Check wind direction leaving the target area.
• 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.)