MRLs Pose a Challenge for California Tree Nut Growers

Inconsistent requirements can be problematic when exporting

Exporting crops and commodities expands production and increases demand both abroad and here at home. Food safety is always a top priority for growers, especially when addressing exports. Maximum Residue Limits (MRLs) have been put in place to establish limits and standards for safe levels of pesticides remaining on nuts when they are imported into other countries.

Currently, an interim MRL is in place for phosphite materials until 2019 while the European Union (EU) determines the standard level. The use patterns of phosphite materials in the U.S. allows potassium and calcium phosphite products to be used as both fertilizers and fungicides. As a result, potassium phosphite was exempt from an MRL. As there was a lack of data available to determine what an acceptable level of residue would be, with no MRL in place, the default MRL of 2 parts per million (ppm) was applied by the EU, a level that would likely be difficult for many growers to comply with, impacting trade of these tree nuts into Europe.

Residues related to phosphite levels became a concern in 2015 when the EU altered the terms of what would be considered a residue to include potassium and calcium phosphites from exports.

This is just one example of how MRLs could potentially impact the ag industry through slight changes to compliance regulations. As MRLs may vary from country to country, it can be a challenge at times for farmers to ensure that crops meet these tolerances, while at the same time keeping up quality standards.  

Here are a few of the common questions we get asked about MRLs:

What are MRLs, and what impact do they have on both farmers and consumers?

MRL stands for Maximum Residue Limit. These values, usually expressed as parts per million (ppm) are the maximum amount of a specific pesticide residue that is permitted on a specific food crop by an importing country. Any pesticide that is applied to a crop will have an MRL attributed to it by the importing country. They were first applied in the early 1960s by the Food and Agriculture Organization. MRLs are one piece of the overall process of ensuring food brought into a country is deemed safe to eat by the government of the importing country.

What crops in California are affected by MRLs?

Any food crop that is exported outside the United States is subject to MRLs.

What is the biggest challenge growers face when complying with MRLs?

MRLs have been in place for years, and usually following the recommended use patterns on the label is sufficient, but not always. A change in an MRL from an importing country could potentially alter the timing, rate of a pesticide, or even eliminate the use of a pest control product entirely. If a new pest control product is produced, it may be necessary for a grower to delay the use of the product if an MRL has not been established for the pesticide and specific crop or crop group in country where the commodity may be shipped. If an MRL can’t be met by the farmer, and the potential of eliminating a specific pest control product would pose a significant risk of crop loss or failure, then the markets for that crop in the importing country would be inaccessible.

What agronomic conditions impact residue amounts and product usage?

Pre-harvest intervals are in place to ensure residues stay below an accepted tolerance level. Residues are influenced by a number of factors: precipitation/irrigation, the crop itself, micro-organism activity, sunshine, etc. All of these elements interact to break down a pesticidal product. Products may break down after a few days - others could take weeks or months.

How have agronomic practices changed to factor in MRLs?

Today, pest control advisors, agronomists and farm managers have to be more cognizant of where their crops are being exported and what conditions are placed on crop production in the destination. Crop protection chemicals that may be registered in the USA may not be permissible in other countries. Grower groups, commodity associations, and companies that export crops outside the USA typically keep their growers aware of changes in MRLs.

How do MRLs potentially impact the crop environment?

If the crop is not exported, MRLs don’t have an impact. If farmers are exporting their crops, MRLs may or may not change the use of a specific pesticide.

What practices, tools or technologies can growers implement to eliminate MRL concerns in California?

It’s important to stay current on any and all restrictions, if the crop is going to be exported.

Where can growers access resources to stay current on approved pesticides for exporting?

Commercial websites such as GlobalMRL.com house databases which can be searched by commodity, pest control product, and country. The Codex Alimentarius sets food standards that are the basis for MRLs in many parts of the world. 

Do you see MRLs impacting agriculture in other ways moving forward?

MRLs are a way to regulate pesticide use, and will likely continue as they have for more than 50 years. As long as good science is used in setting tolerance levels, it is just a part of the crop production process.

What does the general public need to know about how growers respond to MRLs and what it means for their food safety and availability?

This is just one aspect of pesticide regulation, and a component of food safety. Pesticides go through extensive testing just to get registered and be made legal for use on a commodity. MRLs are an additional layer to pesticide regulation. There are many procedures in place to minimize any potential risks to human (and livestock, in the case of feed) health.

All growers exporting their crops abroad need to be aware of the standards for MRLs and continue to monitor them as they change and evolve. Retailers and agronomists also need to take these requirements into consideration as they make recommendations to their customers. These limits are just one step being taken toward improving the quality and standards of our food, and although it’s challenging for growers to comply with them, foreign markets are important for growers’ bottom line.