Why Can’t I Use Propiconazole on Peanuts this Year? A story of MRL’s and International Markets

Alan Henn, Extension Plant Pathologist, Mississippi State University
By Alan Henn, Extension Plant Pathologist, Mississippi State University April 27, 2016 13:54

Related Articles

Latest Tweets

Alan Henn1 with contributions by Michelle Samuel-Foo2

1Extension Plant Pathologist, Mississippi State University

2 Regional Coordinator, IR-4 Southern Region, University of Florida.

mfoo@ufl.edu or 352-294-3991

Most peanut growers have received notification from their buying points not to use any fungicides containing propiconazole this year. This active ingredient is found in about 87 fungicide products labeled in Mississippi, including popular products like Artisan, Bumper, Stratego, Tilt and Quilt Xcel.

Keep reading this blog spot. We are likely to experience similar problems in the future.


In short, because the European Union decided late last year that they did not recognize a MRL for propiconizole in almonds, cherries, plums, strawberries, currants, gooseberries, peppers, cucumbers, globe artichokes, peanuts and tea.

What is an MRL and Why Is It Important?

In order for a pesticide to receive an EPA label, it must have a tolerance. A tolerance is defined as the the enforceable limit on food pesticide levels. In other countries, the equivalent term for tolerance is called the Maximum Residue Level. This is usually abbreviated as “MRL”.

Obtaining a MRL is expensive. For each crop on the label, controlled field residue trials adhering to US EPA mandated “Good Laboratory Practices” (GLP) are necessary. Touching briefly on the expense part:

  • All researchers must be GLP trained – in itself an expensive and time-consuming effort.

  • Every step must follow a strict protocol, and every step must be documented – VERY thoroughly. Read lots of paper work to be filled out at the time of each activity.

  • All equipment (scales, gauges…) must be calibrated and certified by an accredited authority.

  • The chemical of interest must be applied in a manner that reflects local commercial practices.

  • The crop must be harvested according to the correct protocol.

  • The harvested crop must be frozen almost immediately and stay frozen.

  • The crop is processed by a strictly defined method in the lab.

  • Extracts are analyzed (expensive, certified lab machines).

  • All steps are audited.

  • The final step is a data petition that is submitted to the EPA. The process requires from 24-36 months.

Historically, chemical companies who own the patent for the pesticide in the country of use pay for this testing. In some cases, and depending on a wide range of factors, a MRL established in one country may or may not be acceptable in another country. Some countries may not have an MRL for a given pesticide.

If an MRL does not exist, some countries, especially those who are “playing a game” with the exporting country, will refuse entry of a shipment into their country if testing shows ANY residue for the pesticide. No matter how minute the residue.

There are no good options in this situation. The grower/shipper are left with a container or ship full of the crop, in a foreign land, with a lot of money already invested. Sometimes they have no choice but to pay to destroy the shipment or sell it to another country at a large loss.

MRL’s and Older Pesticides

When a pesticide goes off patent, other companies often use it without reimbursing the originating company. When one company using such a product pays for an MRL, then all companies can use that MRL, even though they did not contribute to the (considerable) expense.

Many countries are re-evaluating the MRL’s of older pesticides and the data on which the MRL’s are based. This is a slow process that will require some years to complete.

What’s Happening?

Late last year, the European Food Safety Authority published its review of the older fungicide propiconazole (EFSA.propiconazoleOpinionMRL).

The European Food Safety Authority concluded that the data were insufficient to set an MRL for almonds, cherries, plums, strawberries, currants, gooseberries, peppers, cucumbers, globe artichokes, peanuts and tea. In addition they concluded that the residue data were only sufficient to determine tentative MRL’s and risk assessment data on all other commodities.

As a direct result of this finding, those crops with insufficient data cannot enter the European Union.

If the pesticide is to be used in products produced or imported into that country, someone will have to pay for new MRL data.

I am not sure what effect the finding of tentative MRL and risk assessment data will have on other crops in the medium or long run. My guess is that if any one raised questions about or challenged them, the agency would opt for safety and revoke the tentative MRL and risk assessments.

Who will pay for a new MRL ?

This is a good question that not only affects propiconazole, but will effect most of the other older pesticides.

In some cases, a pesticide company might pay. To make that work, the company would have to own a good portion of the market for the pesticide in the country and that market would need to be capable of paying for the expense of the MRL in a reasonable time. In many cases this will not occur due to market fragmentation.

In some cases where a pesticide is essential to the production of a crop, a grower group or industry might pay for the work to support their crop.

In other cases, there might be sufficient demand from multiple producers and industries in the country to pressure the central government to fund the necessary MRL studies themselves.

Collaborative efforts are the most likely mechanism by which many of the pending MRL issues might be resolved. But what might these collaborative efforts look like and who might run them? Such efforts will require a pool of skilled people backed by good infrastructure. A solid reputation would help.

IR-4, an Example of Collaborative, Cost Effective Effort

Historically, the IR-4 Project has striven to label pesticides, often already labeled for major crops (such as corn and wheat), for use on specialty crops. A specialty crop is defined as fruits, vegetables, tree nuts, herbs and nursery/floriculture crops. IR-4 also assists with registrations of minor uses on major/semi-major crops e.g. support for a miticide on peanuts as well as public health pesticide uses (mosquito, ticks, flies).

I cannot think of a single pesticide labeled for use on sweet potatoes that has not been supported by the IR-4 project.

More recently IR-4 has collaborated with the EPA and similar agencies from other countries to:

  • Expand crop groupings. Establishing an MRL is expensive. Prior to 1983, an MRL had to be established for each pesticide/crop combination on which it would be used. Starting in 1983, crops with similar botanical and taxonomic characteristics were combined into “crop groups”. An MRL generated on a representative member of the crop group (usually the member of the crop group that represents the worst case scenario) would count for all members of the crop group*.

  • Make MRL studies more cost-efficient:

    • IR-4 has also cooperated with agencies in other countries to conduct identical MRL protocols on the same crop in tropical, semi-tropical and temperate countries to see if and how crop residues might differ.

      • Studies are ongoing, but at this time, it appears that residue levels are comparable across climates and regions – when the studies are carefully controlled as outlined earlier.

      Either the expanded crop groupings or the climate/residue results alone would have a major financial and agricultural impact. The potential of this combination will have a major impact on agriculture and simplify international shipping of our crops.

      The collaborative efforts of the IR-4 Project have had a significant impact on American agriculture. The IR-4 Project is a United States Department of Agriculture-National Institute of Food and Agriculture (USDA-NIFA) sponsored program that receives support and funding from a mixture of sources including: USDA-NIFA, University Experiment Stations/Extension Services, and private industry.

      The project has faced budgetary challenges in recent years and is currently undergoing an organizational assessment to increase the efficiency of the program while trying to maintain its level of service to its stakeholder base

      Collaborative efforts such as those led by the IR-4 are the only mechanism by which I see many of the pending MRL issues being worked out. If you are in contact with our legislatures, please mention to them the IR-4 Project and importance of adequate funding for its work.

      *Example: Sweet potato is the representative crop for the ‘tuberous corm vegetables (except potato) subgroup under root and tuber vegetables. Residue work supporting a registration on sweet potato, will also support registrations for the 15 other members of this crop group.

Print Friendly, PDF & Email
Alan Henn, Extension Plant Pathologist, Mississippi State University
By Alan Henn, Extension Plant Pathologist, Mississippi State University April 27, 2016 13:54
Write a comment

1 Comment

  1. Phil McKibben April 30, 22:43

    Excellent article. I have seen firsthand the benefits to the sweetpotato industry in Missisippi that have come about because of the IR-4 program mentioned above. We currently have more insecticides labeled for sweetpotato than at any time in the past 15 years. This is certainly not true of most other crops.

    Reply to this comment
View comments

Write a comment


Subscribe to receive updates

More Info By