Protected Agriculture Standard: Important Information about Dye Test Audits for Growers

We’ve written before about the National Protected Agriculture Standard and what it means for greenhouse floriculture growers. The standard, which is administered by CropLife Canada, comes into effect January 1, 2024. The goal is to keep plant protection products where they are applied.

In order to purchase pesticides going forward, your farm will need to be certified under the program as of January 1, 2024. All greenhouse growers who self-identify as having a recirculating (closed-loop) irrigation system need to register and complete an audit by December 31, 2023 to be certified. Open system growers will need to obtain an exemption in order to continue purchasing products. Greenhouse grown cut flowers and hoop houses that do not recirculate their water are currently out of scope, but they will be added to the standard in the near future.

To comply with the standard, growers need to undergo an audit every two years and have a test done to confirm the integrity of your irrigation system every 6 years (every third audit). The preferred option for the irrigation system test is currently a tracer dye test. However, other options including visual inspections with cameras or pressure tests, will also be accepted. OMAFRA and FCO wanted to run a trial of the tracer dye test to test it out before farms started with their own audits.

Why did we do this trial?

  • Many commercial floriculture greenhouses have little to no downtime to schedule irrigation system audits.
  • Tracer dyes can be used to test the integrity of irrigation systems, but this is usually done when crops are not present.
  • Maintaining plant quality is critical.
  • Growers need to know if the dye affects crops so they can plan for audits.

How did we do it?

Tracer dye applied on flood tables

We focused on major irrigation systems that are either recirculating or might be used in a recirculating system. These included sub-irrigation (e.g. flood floors, tables or troughs), overhead irrigation (e.g. booms in propagation or general production) and irrigation drip line (e.g. hanging baskets, in pots on flood floors, in outdoor production on engineered beds).

We looked at common crops with white blooms so we could easily see if the dye caused damage. The following crops were tested:

We applied the dye at the recommended rate once, as it would be done in an audit. Crops were then irrigated as normal for a week after the initial dye application. Final damage assessments were taken one week after the dye was added to the system.

What did we learn?

  • We did not see any damage in the sub-irrigated or drip irrigated crops we tested.
  • Overhead irrigation leaves a residue, but it can be washed off flowers and foliage with a thorough rinse. The same goes for benches, floors and pots.
  • The tracer dye is visible even at low concentrations, diluted up to 100 times.
  • The dye can be retained in pots and on cut flower stems. Make sure plant material has been rinsed and pots (especially clear ones!) flushed before plants head to retail.
  • Flush irrigation lines and drippers well to make sure the dye doesn’t linger in your system.
  • If possible, take this opportunity to sanitize your irrigation equipment!
Residue left by the tracer dye on cyclamen.
After rinsing, the dye residue comes off.

Want more information? Check out this presentation with more details on the trial. If you have further questions about the Protected Agriculture Standard and how it applies to your farm, you can follow up with Cary Gates, Pest Management Director at Flowers Canada Growers (

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