Letter says aerial application safe around bees

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A suggestion that aerial application of pesticides is inherently unsafe around bee colonies is countered by Scott Bretthauer, Ph.D., Extension specialist, application technology, University of Illinois. Bretthauer responded with a letter to the editor after reading a short item on the “Profit Tips” page of the June issue of AgProfessional magazine.

Of the six tips for “Ways applicators can protect honey bees,” Bretthauer objected to the wording of tip number five which paraphrased Oregon State University suggestions for applying pesticides around honey bees. The tip as printed in the magazine was: “Ground application generally is less hazardous than aerial application. During aerial application, do not turn the aircraft or transport materials across blooming fields.”

Below are the extensive comments by Bretthauer; all make sense and we appreciate him providing them:

As an Extension specialist in application technology who works with both aerial and ground applications, I would like to offer the following comments to the short article titled “Ways applicators can protect honey bees” on page 14 of the June 2012 issue of AgProfessional magazine.

  1. The point suggesting ground application is less hazardous to honey bees than aerial application is unwarranted. When conducted properly, aerial application poses no higher risk to bees than a ground application.
  2. It recommends that during aerial applications “do not turn the aircraft or transport materials across blooming fields.” I do not believe this recommendation is justified. Agricultural aircraft are equipped with a number of devices that ensure spray is not inadvertently released outside of the target area. These include check valves on each nozzle and a suck back system that creates a vacuum when the spray system is off. In addition to these devices, aerial applicators routinely inspect their aircraft to ensure there are no leaks in the spray system.
  3. While the article does not mention drift, an examination of the Pacific Northwest Extension publication referenced at the bottom does state that “less drift occurs” with ground application. Drift is primarily a function of droplet size, wind speed, and wind direction. It is true agricultural aircraft can be set up to have a smaller, narrower droplet spectrum than ground rigs.This is one of the reasons aerial application is more effective at applying insecticides than ground rigs. A narrow, small droplet spectrum provides good coverage and deposition, which increases the efficacy of the application. It is the smaller droplet size, however, that would increase the risk of drift, not the aircraft itself. Agricultural aircraft can be set up to provide a large, drift resistant droplet size if the application calls for it. 

In terms of wind speed and wind direction, aerial application is the preferred application method because agricultural aircraft are able to make an application in a much shorter time period than ground rigs or other forms of application. If there is a narrow window of favorable wind conditions for making the application, an agricultural aircraft can likely get an application made when a ground rig would be unable to. If a section of a field needs to remain temporarily untreated because wind direction is towards an area where bees are present, it is much easier for an agricultural aircraft, due to quick ferry times and GPS/as-applied technology, to return to treat the temporary buffer zone once wind direction has shifted away from the sensitive area. Ninety-nine percent of aerial application aircraft, according to a recent National Agricultural Aviation Association survey, are equipped with GPS systems which provide precise information to the ag pilot on the entry and exit points of the field and when to engage the application procedures.

 4. For a variety of reasons, including effectiveness, timeliness, and no damage to the crop, aerial application is the better method for applying insecticides. With a properly set up and operated aircraft, the hazard to bees is no greater than with a ground rig, and is probably less because of the aircraft’s ability to complete applications quicker within desired weather conditions.

Having worked with aerial applicators for a number of years and having conducted a number of aerial application pattern testing clinics, I believe there are many benefits this form has over other forms of applications, and, if used correctly, has no additional risks to bees or other sensitive entities.


Scott M. Bretthauer, Ph.D.

Extension Specialist –Application Technology

University of Illinois

Department of Agricultural and Biological Engineering 

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Tom Theobald    
Colorado  |  July, 06, 2012 at 08:57 PM

Although the headline desperately proclaims "Letter says aerial application safe around bees", Dr. Bretthauer's letter says nothing of the sort. At best, Dr. Bretthauer tells us, aerial application is no greater a hazard than ground application. Neither the original article in question or Dr. Bretthauer claim that ground applications are safe, and by his own comparison, nor are aerial applications. Dr. Bretthauer is careful to qualify his assertions. "When conducted properly,,," or "With a properly set up and operated aircraft..." In reality conditions are rarely ideal.

Jay Sharp    
Iowa  |  July, 07, 2012 at 06:07 AM

I operate an aerial application business in Iowa and our law allows for applications within 1 mile of bee hives early in the morning and late in the evening. I routinely make applications right next to hives within these guidelines and have been doing so for years without any harm to the bees. I can do this comfortably because professionals like Dr. Bretthauer provide our industry with modern testing practices that allow me to set my aircraft up to be ideal for various situations. I take offense to Tom Theobald's comments, as a profeesional, I will not allow one of my aircraft to leave the ground unless I know that every aspect of the situation is ideal.

Jeff Anderson    
Minnesota  |  July, 08, 2012 at 08:17 AM

The letter by Scott Bretthauer and both of the comments seem to miss one major point; bloom. If either the target application site OR surrounding areas that may recieve drift have bloom, and the application of pesticide is an insecticide, then Oregon States reccomendations are very valid. Many insecticide are Extended Residual Toxicity which means that because they are toxic for greater than 8 hours they may not be applied to bloom. These have a bee hazard statement which generally says "do not applied this product or ALLOW RESIDUES on blooming crops or weeds if bees are VISITING the treatment area. Again this issue is bloom, some insecticides can be applied to bloom if it is done when insect pollinators are not active, generally this is at night. So while it may be true that an aircraft damages less crop, is much quicker at making the application etc, often pilots are reluctant to fly at night when pollinators are not active. Most ground rig operators are less intimidated by night applications, and for this reason may be the better option if an application to a blooming crop is desired. An insecticide with a short residual will have a bee hazard statement which leaves off the word RESIDUES, and includes the word ACTIVELY before visiting... Do not apply this product or allow it to drift to blooming crops or weeds if bees are ACTIVELY VISITING the treatment area. Just another thought for this discussion...

Rodrigo Zaluski    
Brazil  |  April, 25, 2013 at 07:47 PM

This publication is only on opinion. There aren't a scientific evidence of this information. This opinion including don't is published in a Scientific Paper.

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