Accurate and timely data on the frequency and intensity of herbicide applications on major crops are needed at the county, state, and national levels to help scientists, regulatory agencies, and farmers recognize when there is slippage in the efficacy of current weed management systems. It is also vital in identifying which herbicides warrant closer scrutiny because of markedly rising use.
In the Midwest since the late 1990s, the rapid adoption of GMO corn and soybean seeds led to sharply rising use of glyphosate-based herbicides (GBHs). In 1995, 20% of the national soybean crop was sprayed with about 0.6 pound of glyphosate, for a total of 7.6 million pounds applied. In 2016, 91.5% of soybean acres were treated with an average of 0.9 pounds, resulting in a total of over 102 million pounds — more than 13-times more than in 1995!
Beginning in 2016 and upon the approval of soybeans and cotton crops genetically engineered to resist both GBHs and dicamba, use of the high-risk herbicide dicamba began rising, especially in states on the southern edge of the Cornbelt. Beginning in crop season 2019, newly approved GMO soybeans resistant to both GBHs and 2,4-D will begin driving use of 2,4-D upward.
The Heartland Study will deploy the Pesticide Data Use System (PUDS) in tracking a complex set of 18 indicators of herbicide use in our 13-state study area. We describe PUDS in this section. Key indicators of change in herbicide use are introduced in the next section (Key Indicators), or see the section “Interactive Herbicide Use Tables” to learn more about herbicide use trends and access our huge database.
About PUDS – The Pesticide Use Data System
PUDS is a U.S.-focused pesticide use analytical system created by Heartland Study Science Advisory Board member and Project Coordinator Dr. Charles Benbrook. PUDS is accessible via Dr. Benbrook website Hygeia Analytics here.
PUDS utilizes the annual pesticide use data collected and published by USDA’s National Agricultural Statistics Service (NASS), via their online Quick Stats Database.
NASS requires a subset of U.S. farmers to report the amount and frequency of pesticides applied to crops, typically on a bi-annual basis for fruits and vegetables and periodically for grain and row crops.
In each year for all crops surveyed, NASS strives to collect data from states that together account for at least 85% of the acres planted nationally to a given crop.
This crop-by-crop, state-by-state and national information is downloaded from Quick Stats each year, and incorporated into the pesticide use database that supports PUDS.
PUDS is then used to generate a series of tables assessing pesticide use by crop, by type of pesticide, and by specific active ingredient, as well as trends over time.
PUDS data elements are downloaded from two separate components of Quick Stats. The total acres planted to a specific crop are reported by state and national totals, and are extracted from the Quick Stats crops sector. All other pesticide use data are reported under the Quick Stats environmental sector.
Key PUDS data elements include:
Crop – Crop surveyed by NASS.
Year – Year the crop was surveyed for pesticide use.
State – The state the crop was planted in. ‘National’ in the state description designates national use of the pesticide.
PC Code – EPA’s coding system for each pesticide active ingredient registered by the EPA.
Active Ingredient Type (AI Type) – The active ingredient type designates whether the reported chemical was used as an herbicide, insecticide, fungicide or other pesticide. Very rarely, but in some instances, a chemical may be used as an herbicide in one treatment and a fungicide in another treatment.
Chemical – The pesticides applied to crops are reported according to their PC code and active ingredient name as designated by the Environmental Protection Agency (EPA). Brand or product names (e.g. Roundup) are not published by Quick Stats.
Conglomerate – NASS sometimes reports pesticide use separately for different chemical forms of the same active ingredient (e.g., 2,4-D Diethamine salt and 2,4-D Isoprop Ester). The conglomerate field is used to sum, or group, all such compounds into an aggregate total for the active ingredient. See the “Conglomerate Pesticides” tab/section for methodological details.
Total Acres – The total number of acres that is planted to a specific crop for each state and national totals.
Note — In the case of some crops (fruit and nut trees, bushes and vines), USDA may report bearing acres as opposed to planted acres, since these crops are not replanted annually. In such cases, acres bearing, or acres harvested in a specific year is assigned as the Total Acres Planted value.
Surveyed Acres – The number of acres surveyed by NASS within each state.
Note — Surveyed acres is not always the same as total acres planted. USDA strives to survey crop-pesticide use in a combination of states that collectively account for at least 85% of the total acres of a given crop planted nationwide. Accordingly, some pesticide use tables report values for surveyed acres, as well as total state or total national acres. Total state and national pesticide use are estimated based on the assumption that the percent acres treated, and rates per crop year on surveyed acres is the same as on the acres not surveyed by NASS.
Percent Acres Treated – The percentage of total acres of a given crop within a state that was treated with a given pesticide. In Quick Stats, the data item = Treated, measured in percent of area planted.
Number of Applications – The number of times a pesticide was applied within a crop year. The Quick Stats data item = Applications, measured as the average number of applications across all acres treated with a given pesticide.
Rate of Application – The average active ingredient rate per acre where the pesticide was applied in a one-time application. Quick Stats data item = Applications, measured as average lb / acre / application.
Rate per Crop Year – The rate per acre where the pesticide active ingredient was applied throughout the year. This is the average rate of application multiplied by the number of applications. Quick Stats data item = Applications, measured as average lb / acre / year.
Pounds Applied – The pounds of pesticide active ingredient applied to the acres of in a surveyed state. Quick Stats data item = Applications, measured in lbs.
Calculated Pounds Applied to Surveyed Acres – The pounds of pesticide active ingredient applied to surveyed acres, calculated based on Quick Stats data.
Calculated Pounds Applied to Total Acres – The pounds of pesticide active ingredient applied to total acres planted of a given state/crop.
Surveyed Year – Designates whether use data of a pesticide was originally surveyed by NASS for each crop/state/AI type/pesticide.
There are instances in Quick Stats where a data element is reported as undisclosed (D), or as insignificant data (Z). In such cases, there may only be one farmer within a state growing a specific crop, which renders the data undisclosable because of NASS privacy protection policies.
We have developed methods to estimate most unreported values from those data elements that are reported.
In cases in which a pesticide is applied on less than 1% of acreage, NASS sometimes does not report percent acres treated and/or pounds applied. In such cases, we set the percent acres treated at 0.5% and calculate the pounds applied based on other available data.
NASS sometimes reports the use of an active ingredient that is manufactured and sold in slightly different chemical forms as two or more distinct active ingredients. In most tables derived from PUDS, all variations of a parent chemical are grouped together and reported as one parent pesticide, what we call a “conglomerate” value. For example, NASS reports 2,4-D Diethamine salt and 2,4-D Isoprop Ester as two separate chemicals. In such cases, we create a conglomerate set of 2,4-D use data that combines the use of the two separate forms of 2,4-D.
The application rates and number of applications for conglomerate active ingredients are calculated using a weighted average approach, based on the percent of acres treated with each individual form of the active ingredient, relative to the sum of acres treated with all forms. Conglomerate pounds applied is simply the sum of all chemical variations of a given active ingredient.
The U.S. Department of Agriculture (USDA) has collected reasonably comprehensive pesticide use data for major grain, row crop, fruit, and vegetable crops since 1990, and a few periodic surveys are available to track pesticide use on major crops going back into the 1970s.
Pesticide applications at the national and state level have been reported since 1990 by NASS for most major field crops; fruit crops have been surveyed in odd years; and, vegetables have been covered in even years.
Because of budget limitations in the last decade, NASS has limited the number of crops surveyed in any given year. For example, soybean pesticide use was surveyed annually from 1990-2002, in 2004-2006, and then not again until 2012 and 2015. Pesticide use on corn was surveyed each year from 1991-2003, in 2005, 2010, and 2014.
The absence of annual survey data for many crops creates gaps in PUDS. To overcome this shortcoming, a series of methods have been developed to approximate missing data values by interpolating between years with reported values. The default assumption is that pesticide use changes by the same proportional amount year to year between two known values.
The following methodology is used for calculating the missing data values:
Years prior to the first year an AI had reported usage, the data values are set to 0.
Years after the last year an AI had reported usage, the data values are extrapolated forward as equal to the last crop/state surveyed year.
If an AI did not have significant reported usage in a given year for a crop/state that was surveyed, then it is set to 0 for the year surveyed. (See below for further implications).
All other years are interpolated between two known years. In years that are set to 0, it is assumed that a straight-line, phase in/phase out period for the AI was implemented by farmers (see below for further implications).
There are cases where Quick Stats does not fully report use data for some pesticide-crop combinations when: (a) the pesticide is applied on less than 1% of acres, (b) a trivial amount of a low-dose active ingredient is applied, or (c) when only one or a few producers reported use of the pesticide, raising confidentiality concerns. In such cases, the unreported AI’s are accounted for by subtracting the sum of pounds applied of the reported AI’s from the total pounds applied (given by Quick Stats) for each AI type (H/I/F/O) and grouped as ‘Other’ Fungicides/Herbicides/Insecticides/Other Pesticides.
In cases where all the AI’s for an AI type (herbicides, insecticides, fungicides, other) are not reported, then all of the pounds applied and percent acres treated are used to fill in the data gap and interpolated using the methodology above.