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Tips for Controlling Drift Spray

Drift spray is the movement of herbicides or pesticides from the area it is being used on to areas they are not intended to come in contact with. Drift spray can expose people, wildlife and the environment to hazardous residues that can cause property damage and affect your health Controlling drift spray is a critical part of using these types of applications and several methods are used to help in that effort.

  1. Spray Particle Sizes

    • Larger spray droplets are less likely to travel on the wind than smaller lighter droplets that act more like mist. There are additives for pesticides and herbicides that act as thickeners and can help increase the droplet size to assist in this effort. The application does have an effect, as ground sprayers are more effective with use of thickeners than aerial-type sprayers. Reducing the spray velocity and adjusting the spray nozzle can also be factors in increasing droplet size. Larger droplets also adhere better to certain types of foliage and this can increase effectiveness for the product as well.

    Equipment

    • Changing nozzles on a sprayer can affect the spray and assist in controlling drift. Nozzles that act as a mist-type applicator are more likely to produce spray that floats on the air and may drift. Using a lower pressure nozzle and also one operated from the ground rather than an aerial or blower spray device reduces drift. Lowering the arm of the sprayer, or boom, also assists in directing the spray more closely to the area desired rather than allowing it to float to the target location.

    Weather Conditions

    • Choosing the time to use products that can drift is a factor in application and reducing drift. Wind, temperature and relative humidity have an effect on the size of the droplets, causing them to drift or evaporate more quickly. High winds drift even heavier, larger droplets, and low humidity with a high air temperature causes evaporation, reducing the droplet size and causing it to be carried further away from the target location. Weather factors need to be considered in the timing of applications in order to control spray drift.

    Operator Care

    • Careful monitoring of conditions, proper use of equipment and taking care to be mindful of safety are the operator's job when it comes to reducing drift spray. Not just a concern for his own personal health and safety, the result of his job can affect many. Decisions on whether to postpone application, regular equipment maintenance and proper operation during use, and monitoring the job while in progress all are factors the operator must handle to control drift spray.

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