The Results are in: Pesticide Residues in Produce

Vegetable growers are familiar with pesticide labels that specify how much of a product may be applied. As commercial growers, we usually think about such instructions as telling us how much pesticide is the right amount to apply to a crop to be effective. While such an interpretation is correct, there is more to the labeled rates of a pesticide.

While many researchers (including myself) are involved with experiments to try to manage pests with pesticides, others are involved in trying to determine the pesticide concentrations that may safely exist in the produce we all eat. The latter is known as the pesticide tolerance. Both efficacies of the pesticide and human safety are involved in determining the label rates and timing of each pesticide. Indeed, some pesticides are not labeled for certain crops for reasons of safety.

There is mostly good news in the just released 2015 Pesticide Data Program. Each year, the USDA’s Agricultural Marketing Service (AMS) publishes a Pesticide Data Program Annual Summary. The report includes produce from all over the U.S as well as imports from other countries. While the report is rather long and complicated, the aim is to determine the pesticide tolerances in produce in the U.S. for 2015. The types of produce tested are rotated every year. In 2015, the produce tested included: apples, cucumbers, lettuce, strawberries, sweet corn, tomatoes, watermelon and many more.

The good news is that out of 10,187 samples, only 441 samples (0.53%) were reported to the FDA (Food and Drug Administration) as Presumptive Tolerance Violations (pesticide residues over the established limit). Out of the 441 tolerance violations, 4 were from cucumber, 2 from tomato and 6 from watermelon. See the report at the link at the bottom of this article for the full list.  While there is no mention of where the violations were found, we want to make sure that in Indiana we do our best to avoid any violations. We all want a better report next year.

What causes pesticide tolerances to be exceeded?

  1. Too much of a pesticide is applied. This can happen if:
    1. The upper limit of a pesticide rate is ignored or misread.
    2. The pesticide is incorrectly applied due to a calibration error or a field overlap.
    3. Too many applications of a pesticide are used in a season. Many pesticide labels state how many applications can be made in a season.
  2. An application of a pesticide is made too close to harvest. The Pre-Harvest Interval (PHI) lets growers know how close to harvest a pesticide may be applied. (The Restricted-Entry Interval (REI), in contrast, is used to protect workers who may come in contact with a pesticide).

Much research has been conducted to assure that pesticides applied according to the label will result in produce within the pesticide tolerance. Fruit or vegetables treated with pesticides according to the label are very unlikely to have pesticide tolerance violations.

To stay within the pesticide tolerances set for produce, growers should:

  1. Read the label.   Even if one has used the product in the past, read the label again for changes.
  2. Consult Extension Guides like the Midwest Vegetable Production Guide for Commercial Growers (ID-56) for changes and guidelines. Consult an ID-56 of the current year, not an old version.   But remember, the authors of the ID-56 can make mistakes. Always rely on the label for rate and timing information. Use the ID-56 as guide only.
  3. The Vegetable Crops Hotline is another good source of information.
  4. Contact your favorite Purdue University Extension Specialist. We can help you with rates of pesticides, up-to-date information and pest management techniques. Better to call than to make a mistake.

The full report is available at  https://www.ams.usda.gov/datasets/pdp. If you have questions about the report or this article, feel free to contact me. I look forward to reading an even better report card from the AMS next year.

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