In many articles critical of modern agriculture the narratives about pesticides tend to use terms like “slathered,” “drenched,” or “doused.” These are alarming images and foster consumer fears about the role of pesticides in the food supply. Those actually involved in the control of pests on farms know that these are extremely misleading impressions of how farmers manage their crops. It is useful to make some visual comparisons to provide perspective.
“Slather” is a term we use to describe the process of applying a heavy dose of sunscreen. Putting 1/2 ounce of sunscreen on just your face (57 square inches) would amount to 0.009 ounces/square inch. If an acre of a farmed crop were “slathered” to that same degree, that dosage would be more than 54,000 ounces per acre. Most crop protection products are applied in the range of 3 – 64 oz. per acre. That means that the sunscreen slather image is exaggerated by a factor of 850 to 18,000. The use of the term “slather” is completely inappropriate when describing the use of pesticides in agriculture. “Petroleum distillates” (essentially mineral oils) are organic-approved pesticides that are applied at rates up to 1792 oz. per acre. Even that wouldn’t qualify as “slathered” in comparison to the sunscreen.
One reason people may imagine high pesticide use rates are the images of the spraying process. Most pesticides are delivered in a water spray. The actual amount of pesticide involved might range from a few ounces to a few pounds per acre, but is diluted in much more water. To get good spray coverage of something like an orchard crop, it might be necessary to use 100 to 400 gallons of water per acre. To be clear, that spray is almost all water. For something like an herbicide application to a row crop, the “spray volume” might be only five gallons of water per acre, again delivering a few ounces to maybe two quarts (64 oz.) of actual pesticide. How does a farmer’s use of five to 400 gallons per acre of water compare to the emotive terms “drenched” or “doused?”
If you get caught in a sudden thunderstorm you might say you got “drenched.” If you were not in the rain too long that drenching might represent five one-hundredths’ of an inch of rain. On an acre that amount of rain would represent 1,358 gallons – far more than even the largest volume used for a crop protection spray.
When you put milk on your breakfast cereal (say ¼ cup to a bowl that is six inches across) you might say you “drenched” it. If that kind of volume were put on an acre of land, it would represent 3,465 gallons – eight to 700 times more than the water volumes in agriculture. Again, “drenched” is a seriously misleading way to describe what farmers do when they spray.
There is a tradition of “dousing” a winning race car driver with Champagne. That seems like a waste of good Champagne, but let’s assume only half of the bottle actually goes on the winner’s head. To apply that sort of volume to a farmed acre would represent 16,148 gallons. So what a farmer might ever apply should really not be described as “dousing” the crop.
Farmers don’t have any incentive to spray more crop protection agent than they need – these products cost money. A farmer also has no incentive to spray with a bigger volume of water than is needed to get the agent effectively delivered.
So when you hear or read about farmers “slathering,” “drenching,” or “dousing” their fields, remember that these emotive terms and mental images are at best, misleading, and frequently, manipulative.
This article originally appeared on Putting Pesticides in Perspective here and was reposted with permission of the author.
Steve Savage is an agricultural scientist (plant pathology) who has worked for Colorado State University, DuPont (fungicide development), Mycogen (biocontrol development), and as an independent consultant. His blogging website is Applied Mythology. You can follow him on Twitter @grapedoc.