Herbicide Metrics – A Short Review of the Science of Herbicide Use
The map below illustrates soybean yields in the state of Illinois. It tells us that soybean fields are found in almost every county. Seems simple enough, right?
But, how we would measure herbicide use on the state’s soybean crop is actually quite complex. Eighteen different metrics are needed to paint a complete picture of how herbicide use has evolved in Illinois, and throughout the Midwest.
Metrics by Active Ingredient
1. Percent of Acres Treated
2. Number of Acres Treated
3. Acre Treatments
4. Rate per Application
5. Number of Applications
6. Rate per Year
7. Pounds Applied
Metrics on High-Dose vs Low-Dose Chemistry
8. Number Low-Dose Chemistry
9. Reliance on Low-Dose Chemistry
10. Number High-Dose Chemistry
11. Reliance on High-Dose Chemistry
12. Weighted Average Rate of Applications
Metrics by Type of Pesticide (Herbicide/Insecticide/Fungicide/Other or H/I/F/O)
13. Number of H/I/F/O A.I.’s Applied
14. Number of H/I/F/O A.I.’s per Acre
15. Number of H/I/F/O Acre Treatments
16. H/I/F/O Acre Treatments per Acre
17. Pounds of H/I/F/O Applied
18. Pounds of H/I/F/O Applied per Acre
Monsanto first introduced glyphosate-resistant crops in 1996.
Soybeans are the #2 crop in the U.S. The fact that they are also one of the first to be genetically engineered (GE) to be tolerant to glyphosate herbicides makes them the perfect lens to look at changes in pesticide use since GE crops were introduced.
These GE seeds produce crops that didn’t die when sprayed with glyphosate, allowing farmers to use these herbicides over the top of green fields to control weeds throughout the growing season. Glyphosate-based herbicides, with the first being Monsanto’s Roundup, quickly took over the market. Glyphosate became the Midwest’s #1 herbicide in 1998, just two years after glyphosate-tolerant crops were introduced.
Over the next decades, glyphosate use would skyrocket. And, in recent years, these data also show the rise in 2,4-D and dicamba. Herbicides made with these older, high-risk active ingredients have seen increased use due to the spread of weeds resistant to glyphosate (see chart on right).
Acre-Treatments: Glyphosate, Dicamba and 2,4-D
2) An increase in both the number of applications and the rate of application per acre per year.
Both of these factors are, in turn, driven by the introduction of glyphosate-tolerant, Roundup Ready crops in 1996.
Data at the state level tells a similar story.
Let’s take a look at the state of Illinois, where for several years nearly 100% of the soybean acreage was sprayed with glyphosate.
What changes are ahead?
The Heartland Study has projected changes in glyphosate, dicamba, and 2,4-D use in soybean production through 2030, based on industry estimates of the percent of the soybean seed supply that will contain resistant genes in various combinations.
Will the future bring a new #1 herbicide?
What about other pesticides?
Use of other pesticides, like insecticides and fungicides, on other crops, like corn, is also on the rise.