Trends in corn herbicide use (1990 to 2014)

USDA-NASS recently published the most recent corn herbicide use data (from 2014). I’ve been looking through the data, because, well, free data! Perhaps the figure below isn’t the ideal way to present it, but there are some interesting trends that can be observed this way. Total herbicide use in corn (in weight of herbicide applied) has remained relatively constant at about 2 to 2.5 lbs/acre since around 2000 (Top panel A). There have certainly been changes in which herbicides contributed to that total, though. Alachlor and cyanazine use has stopped due to health and environmental concerns. Butylate and bromoxynil declined; an argument could certainly be made that this was due to farmers switching to glyphosate in Roundup Ready crops. Metolachlor and dimethenamid also declined in weight applied, but this seems mostly due to newer formulations with lower use rates (S-metolachlor and dimethenamid-P).


Simply looking at the weight of herbicide applied doesn’t tell the whole story. Panel B in the figure above shows herbicide application data in terms of the proportion of acres treated with each herbicide. For example, in 2014, atrazine was applied to 55% of corn acres, so the light blue area in 2014 has a height of 0.55. The y-axis exceeds 1.0 (or 100%) because on average, each corn acre received more than one herbicide. If you look at the data this way, it appears there’s been a steady increase in the number of herbicide applications (or  the number of herbicides applied in a single application) for each acre of corn. Bromoxynil, dicamba, dimethenamid, and nicosulfuron all seem to have decreased as glyphosate use increased. These herbicides, therefore, would be candidates for herbicides that glyphosate “replaced” in US corn production. But, even this wouldn’t tell the whole story, as other herbicides like mesotrione and isoxaflutole (in the “other” category) also increased during the same time period.

Below is a more traditional line chart for 20 different herbicides that make up most of the corn herbicide use in the NASS data. There are a total of 56 different herbicide active ingredients, once you combine the various forms of glyphosate, 2,4-D, metolachlor, etc.




  1. Interesting stuff, Andrew, to see how it is in USA, particularly, from the perspective of the Danish public fear of herbicides in the groundwater and in the environment. The URL

    Shows how it is calculated in the State of Denmark, A hot issue. It requires, however, there is a consensus of what is a normal field rate in a given crop . In tiny DK it is easy, but in USA is is probably not that easy

  2. Looks like Monsanto was hiding the incidence of glyphosate-related cancers in their early testing. Does not look good. I don’t trust that company.

      1. Mercola is an M.D. and scientist. What are your credentials? Do you even have a college degree? I prefer intelligent debate rather than blanket dismissal. Shows weak character, and often fear. I have nothing to fear, and no skin in this game, other than my health. You, on the other hand, seem to be predisposed to some corporate shill game. Might be wrong – just what it looks like from a casual onlooker.

        1. Clegg5, it’s always best to cite reputable sources to avoid these types of critiscm. Especially in scientific topics.

          Of course, the article you’ve posted(which ive read) has a severe flaw. It’s mostly speculation from anecdotal evidence. The 1991 research being referenced is not a secret and the EPA had printed a review of studies looking at glyphosates toxcity and reclassified it as “Class E (non-carcinogenicity for humans)

          I hope that cleared up the confusion.

  3. How poisonous is glyphosate which is way up (of course, it’s new), versus the item which is way down, atrazine . Also we know that altrazine does not have a bacterial component, right? I am particularly concerned about intestinal effects.

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