Spray Drift 101 – May 18, 2018

Crop samples submitted to the OARDC Weed Lab (http://owl.osu.edu) with suspected herbicide drift injury symptoms sky-rocketed in 2017 and early indications are for the same trend in 2018.  This is happening mainly because vegetables and fruits are much more sensitive to the 2,4-D and dicamba herbicides grain farmers are now using to kill weeds that are no longer sensitive to glyphosate alone.  There is always some drift; but when crops have an elevated sensitivity to the compounds moving in the environment, everyone sees the effect.

Already in 2018, most grain fields have received burndown sprays containing 2,4-D (and some with dicamba) mixed with glyphosate. Predictably samples from injured fruit and vegetable fields, and orchards are being submitted for diagnosis.  So far, roughly 50% of the samples received are not showing symptoms characteristic of herbicide drift, and that’s significant because our lab rarely receives the samples until they have cleared a pathology screen.  So, while crop injury from drift is up significantly, there are still relatively few instances of damage where drift is clearly the culprit.

A general deterioration in farm community relationships has already occurred in some states, as a result of recent conflicts arising over drift.  Grain, vegetables, fruits, landscapes and natural ecosystems have been damaged sometimes with tragic consequences, following the expanded use of 2,4-D and dicamba. Human nature being as it is, we all tend to look outside to explain our problems before we look inward.  Considering this, it is important to consider other possible causes of crop injury before assuming occurrence of drift from the neighbors’ fields.

  • Keep in mind that the injury symptoms associated with 2,4-D and dicamba are indirect responses of the plant to stress, and may have other causes. For example injury caused by glyphosate, used by most vegetable farmers, can sometimes resemble injury caused by 2,4-D.


  • Volatile by-products of incomplete combustion (think of heating a greenhouse or high tunnel) are also known to cause symptoms on bedding plants not unlike those caused by herbicides.


  • Inadequate decontamination of spray equipment used to apply glyphosate, 2,4-D or dicamba may leave behind trace amounts that are enough to cause injury in a subsequent application to a sensitive crop.


  • Carryover of herbicides used on previous rotational crops, sometimes going back two growing seasons, may cause symptoms on vegetables that can be confused with those resulting from 2,4-D or glyphosate drift.


  • Environmental conditions, in particular flooding during and after crop establishment, may induce symptoms that can be confused with herbicide injury, or they may exacerbate the effects of exposure to trace amounts of residual herbicides in the soil that would normally have no affect.


So, ‘what’s a farmer to do?’, to reduce the likelihood of being hurt by drift from nearby fields?


  • Communicate! Talking with the neighbors is first and foremost. This can be difficult considering consolidation of grain farms and rental of land; but communication is vital in protecting your crops.  Explain that the crops you grow are very sensitive to herbicide drift, and that drift can result in a complete yield loss of a very high value harvest.


  • Communicate! Sign up with the Ohio Sensitive Crop Registry.  Steve Smith, Director of Agriculture with the Red Gold Company, reports that incidents of tomato crop injury from drift have declined dramatically since they required their contract growers to register with the sister-program Field Watch (previously known as Drift Watch).  We know that most, if not all, commercial applicators check the Ohio Sensitive Crop Registry before going out to apply herbicides, so registering is clearly the cheapest (it is free) insurance available.


  • Communicate! Steve also reports that placing “No Drift” signs along field edges helped tremendously.


  • Pay attention to pesticide applications on nearby (and not so nearby) fields. Applications in early morning and evening are especially prone to inversion conditions that keep tiny droplets of spray suspended and prone to drift. It will be prudent to keep a written list of observed applications with date, time and observed conditions (are tree branches in motion, flags straight out, etc?). Photographs taken with a smart phone can be location, date and time stamped.


  • Scout your fields at least every 2-3 days paying special attention to field edges where incoming drift will likely have the greatest effect. Symptoms of glyphosate injury usually take 3 + days to become apparent.  Symptoms of 2,4-D and dicamba can develop in less time, often within 24 hours, when growing conditions are ideal.


  • If you see injury anywhere scout the entire field and the hedgerows. Look for patterns.  Drift usually leaves a path of injured weeds, shrubs and trees (look up) along the way. Trace the path to its apparent origin.


  • Photos are very important but equally so, you need a written description of what each photo is attempting to illustrate and where it was taken. Photograph injured plants and plants that are healthy.  Check each photo to verify that it shows the symptom you are trying to capture.  If it doesn’t, take another in different light, from a different angle, or distance.


  • Create a map of the field or mark an existing map, showing where photos were taken and outlining areas affected and not affected.


  • Communicate! Talk to the neighbor, or the applicator if it was a commercial job. Explain that you have injury, that you have reason to suspect it was drift, and that you are monitoring the situation.  Ask them to identify what pesticides were applied.


  • Maintain normal growing practices. If you seek a settlement you must have yield data, and if yields are lower than expected you do not want your failure to maintain the crop to be the reason.


  • The decision to contact the ODA is personal, although an argument can be made that pesticide applications resulting in drift should always be reported. If you contact ODA there is no cost to you for their services, including their analysis of crop tissue for pesticide residues, but once you have contacted them be certain that they will conduct an investigation.


Thinking about the above points it should be obvious that maintaining high quality and complete field records, year in and year out, is important when drift occurs.  Being able to 1) substantiate your own crop and pest management practices validates that you were not the cause of the problem, and 2) past yield records from the field affected will help support a claim for lost yield.


Remember to communicate with your neighbors each year.  Keep in mind that many grain farmers have no idea how valuable an acre of produce can be.


Finally sign up with the Ohio Specialty Crop Register.  Past experience indicates this may be the single most important step you can take to protect yourself.

Leave a Reply

Your email address will not be published. Required fields are marked *