Herbicide Stewardship and Drift Prevention

Bees on flower

Pesticide applicators should 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, 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.
  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.
      • More information here.

Herbicide Stewardship and Drift Prevention

Plan Ahead

  • 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

Off-Target Vegetation 

Climate Conditions

  • 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.)


Protecting Pesticide Sensitive Crops

Protecting Pesticide Sensitive Crops         

Bee Aware

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