by Dr. Jason S.T. Deveau, Application Technology Specialist, OMAFRA, Simcoe
Many years ago (in a galaxy far, far away) the Pest Management Regulatory Agency had an idea to develop a webpage that would provide the reader with clear and concise information on pesticide drift. Specialists were called in, third-party consultants were engaged and the information was hammered into a very nice explanation of what drift is and how applicators can minimize it.
Then someone had the idea to mix buffer zones into the explanation and everything ground to a halt.
In the UK, spray applicators register their spray equipment with government authorities. They sign off on their travel speed, the exact make of their nozzles, their operating pressure, and any drift-reducing modifications they make to their sprayers. When all this information is plugged into some rather complicated formulas, along with weather conditions and the proximity of environmentally sensitive areas, they may be allowed to reduce the labelled buffer zones.
This system is called LERAP (Local Environmental Risk Assessment for Pesticide) and it’s been in place for a long time. Why not in North America? Because we don’t have the same equipment or all the data that makes buffer zone reduction reliable… until now.
I’m very happy to announce the drift mitigation web pages are finally on the PMRA/HC website. They can be accessed by selecting Drift Mitigation. This will take you to the main page. From there you can go to the Buffer Zone Calculator and Glossary of Terms.
This new method for adjusting buffer zones isn’t as quite as sophisticated as the LERAP system, but it’s a great first step. The user will be asked to answer a series of questions about their sprayer, the environmental conditions at the time of spraying, and the proximity of any environmentally sensitive areas. If the applicator is using equipment that is known to reduce drift, and sprays in conditions that reduce the potential for drift, they are rewarded with discount factors that reduce the labelled buffer zones.
I suggest you visit the site and try the calculator. If you’re still interested in learning more about pesticide drift, OMAFRA has just finished a new factsheet: “Pesticide Drift from Ground Applications” Order No. 11-001. It will be printed in full colour and ready in time for the Ontario Fruit and Vegetable Convention. Swing by the OMAFRA booth and pick up a copy.
Yes, finally it exists!
I’m puzzled though as what are the algorithms behind the calculation. I played with a number of important parameters but besides sprayer type and wind speed, many had not impact the calculated buffer zone.
For example the following had no impact on the results
– Reduced product rate (even at 1% the maximum rate)
– Nozzle type
– Operating pressure
Where could we find more info on the calculator?
What are the future work?
I’ll see what I can find out about the parameters that go into the calculation.
Here’s the answer, from Dr. Ted Kuchnicki, PMRA-Health Canada:
“Only the input fields with a ‘*’ are used for the purposes of identification or in modifying the buffer zone. The input factors not identified, such as referenced below, example below have no effect.
… we are currently in talks with the UK LERAP folks to gain permission to import their nozzle classification scheme into our calculator which would allow additional modifications of the buffer zone.
For more detail on the underlying modification factors, you can visit …. http://www.hc-sc.gc.ca/cps-spc/pest/part/consultations/_pro2005-06/index-eng.php
So I understand that nozzles types will be improved in the future using data from LERAP. Perfect.
I’m still puzzled about the dosage.
From section 6.0
“…the calculations are based on the maximum application rate”
but we also read
“…toxicity is expressed as a dose-response relationship between the concentration of the active ingredient and the adverse effects upon the organism, such that increased concentrations of (exposure to) the compound results in increased adverse effects.”
In fact, we know that the amount of active ingredient deposited on the non-target zone is directly proportional to the quantity of active ingredient output by the sprayer.
It is clear that applying 50% of the maximum product rate reduces the adverse effect on the non-target zone by the same proportion. I beleive the actual product rate vs the maximum rate should also be integrated into the buffer zone calculation model.
Thanks for the good questions! I’ve checked with Dr. Kuchnicki:
“The buffer zone size is specific to the product. It is based on the toxicity and the application rate/number of apps/timing (EEC). The relationship between the EEC and the size of the buffer zone is however not direct, thus the modification factor is not constant over a range of possible app rates.
The calculator uses generic modification factors. It would not be possible to make app changes in the calculator specific to a product without actually recalculating the buffer zones in real time.