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Suspect pesticide drift? What to do and how to prevent it from occurring

By Dave Nicolai and Liz Stahl, University of MN Extension Crops Educators

Unfortunately, pesticide applications can sometimes drift onto neighboring crops and vegetation. Damage can range in severity from brief cosmetic symptoms to the inability to market a crop, severe yield losses and/or plant death. Bee kills can also be an issue where pesticide misuse, misapplication, or drift has occurred. The Minnesota Department of Agriculture (MDA) has developed standard procedures to follow when pesticide drift is suspected.

The MDA Pesticide Drift Complaint Process and Timeline

The MDA receives approximately 150 pesticide-related complaints per year. Approximately 66 percent of cases warrant an investigation. Of the total complaints received annually, approximately 40 percent result in financial penalties.

Depending on the complexity and severity of a case, it may take the MDA up to six (6) months to investigate a pesticide complaint, which must be filled out and filed in writing. If you file a complaint, or a complaint has been filed against you, here is what to expect:

  1. An MDA Agricultural Chemical Inspector (ACI) may conduct a site visit within one to two (1-2) business days, sometimes the same day of the incident. 
  2. If the ACI takes crop or vegetative samples, they are submitted to the MDA Laboratory Services Division within one to three (1-3) business days. It may take two to three (2-3) weeks for samples to be analyzed. Lab results are sent to the complainant. 
  3. Ongoing investigations can take from three to six (3-6) months in order for interviews, phone calls, emails to take place. The MDA will also investigate whether potential violations have occurred. In the case of pesticide drift onto organic crops or fields, the MDA Dairy & Food Inspection Division may order crop destruction for safety reasons. 
  4. Enforcement action is determined and put into effect within six to eight (6-8) months from the time the complaint is filed. See the Pesticide drift complaint process and timeline webpage for details. 
  5. Complaints about lost crops or damaged vegetation need to be filed within 45 days of when the event occurred. 
To report pesticide drift, call the Minnesota Duty Officer at 800/422-0798 (day or night, 7 days per week), the MDA Complaint Line at 651/201-6333 (Monday-Friday, 8 a.m. to 4 p.m. ), OR see online instructions for filing a complaint.

FieldWatch: A Tool for Applicators to Prevent Drift Complaints

FieldWatch (which includes DriftWatch and BeeCheck) is a voluntary communication tool that enables pesticide applicators, specialty crop growers (fruit, vegetable, organic), and beekeepers to better communicate and avoid spray drift issues. Growers mark the locations of their sensitive crop sites on an online map (Google Map based) so that pesticide applicators can take precautions to avoid drift when making treatments near these areas. Applicators just need to access the map and zoom into the area of interest to see registered crop and apiary sites. Applicators can choose to register and designate the counties or area of the state in which they operate. They will then receive automatic email notification when a new specialty site is added in their area. To get started, visit

Tactics to Reduce Drift

Select the Right Nozzle for the Job

No one nozzle will be the best for all spraying conditions, although some work well over a range of uses. To determine which nozzle may be best suited for the intended use, first consult the pesticide label for specific nozzle types, carrier rates, droplet sizes, and drift precautions. An example label statement would be: “Apply with 15 or more gallons per acre using a nozzle producing a medium droplet.”

Nozzle selection and pressure should be based on the nozzle manufacturer’s droplet size category charts. Typically, low-drift nozzles will produce spray droplets in the coarse to ultra-coarse range, and minimal droplets in the fine range (which are more likely to drift). Higher spray volumes may also allow the use of larger nozzle orifices (sizes) which produce coarser spray droplets.

Small droplets take more time to fall to the ground and can thus drift farther. It is desirable to use a nozzle that produces large, uniform droplets. Switching from standard flat-fan nozzles (such as an XR11003) to turbulence-chamber or venturi nozzles, increases droplet size and can greatly reduce drift potential. Examples of such nozzles are the Turbo TeeJet and AIXR TeeJet nozzles (Spraying Systems Co., Hypro Ultra Lo-Drift and GuardianAir nozzles (, and TurboDrop nozzles (Greenleaf Technologies

The new phenoxy herbicide formulations, including Enlist Duo™ (Dow), XtendiMax® (Monsanto), Engenia™ (BASF), and FeXapan™ (DuPont), offer growers new management options along with new application requirements. The nozzles and pressures approved for applying these herbicides produce larger spray droplets and reduce the number of fines to manage spray droplet drift. Be sure to check the most recent product label of these products (available online) for approved nozzles and pressures to be used with various nozzles.

Keep in mind the type of product you are working with when using nozzles that produce larger droplet sizes. Target a coarse-sized droplet for appropriate pesticides such as a systemic herbicide like glyphosate. The effectiveness of contact herbicides, insecticides, and fungicides can be hindered if applied in a coarse-sized droplet.

The American Society of Agricultural and Biological Engineers (ASABE) developed a droplet size classification system (ASABE S-572.1) that ranges from extremely fine to ultra coarse, based on measurement in microns. One micron equals one thousandth of a millimeter.

The droplet size category recommended for use with a particular pesticide may be listed on the product label.

Reduce Spray Pressure

Lower spray pressures allow for larger droplet sizes. Be aware that nozzles can produce different droplet sizes at different pressures. Therefore, a nozzle might produce medium droplets at a low pressure but fine droplets at higher pressures. Reducing pressure requires recalibration and adjustments in sprayer speed and carrier volume (gallons per acre).

Monitor Wind Speed and Direction

Always measure wind speed and direction before, during, and after an application. Always follow label information, but in general, wind speeds of 3 to 7 mph are preferable. Make applications at low wind velocities (less than 10 mph). If wind speed or direction changes during an application, immediately adjust the buffer size or location as needed, or stop the application.

Lower boom heights to reduce drift

A wider spray angle allows the boom to be placed closer to the target. The higher the nozzle is above the crop or target, the more opportunity for the wind or air flow to move droplets from the intended site. Spray equipment operated at high speeds can create turbulence in the airflow around the machine that can catch small droplets and make them vulnerable to drift. Determine the optimum boom height for a particular nozzle from nozzle literature to reduce drift potential. If boom height is set too low, uneven patterns in the application or skips may occur.

Avoid Applications During a Temperature Inversion

Applying pesticides during a temperature inversion can result in damaging, long distance drift. Inversions occur when warm air, which is light, rises upward into the atmosphere and cool air, which is heavy, settles near the ground. When cool air settles below warm air, there is no mixing of the air. Spray droplets are not dispersed, staying in a concentrated mass that can move off-target with any subtle airflow. Typically, temperature inversions start at dusk and break up with the sunrise because of vertical air mixing. Use caution when spraying at wind speeds less than 3 mph as a temperature inversion could exist. Refer to a University of Minnesota Crop E News “Temperature inversions: Something to consider before spraying” for more information and an informational video.

Monitor Temperature and Relative Humidity

As the air temperature increases and humidity decreases, droplets evaporate, become smaller and lighter, and travel further.

Know and Follow Application Setbacks

Application setbacks and vegetative filter strips may be required on the labels of pesticide products in order to protect sensitive areas. Read pesticide labels carefully to see whether these practices are required. The downwind buffer areas required on the label may vary in size depending on the rate of the herbicide applied. To maintain a required buffer zone, no application swath can be initiated in, or into an area that is within the applicable buffer distance.

Use Drift Retardants when Appropriate

There are many good products on the market for this purpose. However, some are not compatible with certain drift-reducing nozzle types so ask questions of your suppliers. Drift retardants can reduce drift risk and maximize pesticide performance by binding ultra-small spray particles into larger droplets.

To learn more about spray drift and drift prevention, refer to the University of Nebraska UNL Extension NebGuide Spray Drift of Pesticides.


Bauer, E., Dorn, E., Hansen, P., Hygnstrom, J., and C. Ogg 2015. 5 Things to Know to Avoid Herbicide Drift. Available at (verified 5 June 2015). Univ. of Nebraska, Lincoln.

Minnesota Department of Agriculture 2017. Pesticide Drift Complaint Process and Timeline. (verified 15 November 2018). Minnesota Department of Agriculture, St. Paul.

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