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New PMRA regulations allow use of unlabelled tank mixes

Unlabelled tank mixes can now be used, but make sure the products are compatible and registered for use in the crop. Photo by Bruce Barker.

In a surprisingly quiet announcement in late October 2009, the Pest Management Regulatory Agency (PMRA) agreed to allow the use of unlabelled tank mixes of pest control products for crop production or vegetation management. The new ruling is limited to tank mixes that fall within the registered use patterns for each tank-mix partner. In other words, the products have to be registered on the crop, and used in accordance with label recommendations. For example, a herbicide and insecticide mixed together must both be registered for use on that crop, and applied at the appropriate timing. “I think there are benefits to the new
policy, especially when you look at something like a herbicide and insecticide tank mix. There are times when this type of tank mix makes sense, but most companies don’t seek registration of the tank mix because of the cost of getting it approved,” explains weed research scientist Eric Johnson, at the Agriculture and Agri-Food Canada Scott Experimental Farm. 

Peter MacLeod, vice president of CropLife Canada, says that a typical tank-mix registration takes one to two years and upwards of $100,000 to have registered. The cost is related to proving the tank mix works, and ensuring there are not any compatibility issues. “Our organization had been working with the PMRA for several years to get the policy changed. We believed that as long as the products were registered, the correct rates were used, and the label was followed regarding things like preharvest intervals and timing of application, then there would be a benefit to the farmer,” explains MacLeod.

The new policy does not mean farmers will want to experiment with their own pesticide cocktails, though. Farmers, agronomists and the company reps recommending a tank mix will need to ensure that the products are compatible and that there is not a loss of performance for either product.

The PMRA has laid out guidelines that must be followed if using unregistered tank mixes:
Each tank-mix partner is registered for use in Canada on the crop of interest, including genetically modified crops.
The tank mix only includes an adjuvant when specifically required by one of the tank-mix partner labels. If an adjuvant is not required on the label of any tank-mix partner, then no adjuvant may be added to the tank mix.

The application timings of all tank-mix partners are compatible with regards to crop and pest staging.

Each tank-mix partner is applied in accordance with its registered product label (for example, Directions for Use, Precautions, Buffer Zones, etc.). In cases where information on the tank-mix partner labels differs between them, the most restrictive directions must be followed.
The tank mix is not specifically excluded or contraindicated on either tank-mix partner label (i.e., “do not mix with” types of statements).

The PMRA’s memorandum cautions,  “In some cases, tank mixing pest control products can result in reduced biological activity (antagonism or reduced efficacy), or increased biological activity (synergism or increased host injury). This may be acceptable if there are other benefits associated with using the tank mix (for example, cost savings).”

When it comes to making recommendations for unregistered tank mixes, agronomists, retailers and even farmers making recommendations to neighbours will have to be careful. Risk and liability will reside with those making recommendations, as the PMRA has not reviewed or approved the unlabelled tank mix. “The dealer, agronomist or anyone else making the recommendation will have to be knowledgeable and careful,” says MacLeod. “But at the same time, the pesticide companies have a lot of research and development data that may be used to support an unlabelled tank mix. The companies will be providing guidance to retailers, agronomists and farmers, and in some cases, will even promote the tank mixes.”

The PMRA policy states that pesticide companies, provincial extension specialists and crop advisors can develop compatibility charts and verbal and written recommendations. Unlabelled tank mixes that fall within the scope of new policy also may be promoted, advertised and marketed. The new regulation goes as far as allowing co-packing of pesticides together, even if they are not registered as a tank mix. 

MacLeod says that it is important to remember that the crop and product use must be on the label of each tank-mix partner. He says that company reps will be providing guidance to farmers and retailers on any tank mix they recommend. “The new policy is a win-win-win for farmers, manufacturers and regulators. It will reduce the cost of registration, provide farmers with more flexibility and application efficiency, and recognize the fact that some unlabelled tank mixes were being used anyway,” says MacLeod. 

Johnson says that another benefit of the new policy is that it will help farmers manage pest resistance more easily. For example, AAFC research has found that using a tank mix with several modes of action will help delay herbicide resistance. 

The new policy is also valuable given the number of new generic products on the market. While these products have the same active ingredient, some equivalent products do not have the same labels when it comes to tank mixes. 

Growers should know their chemistries
A downside is that farmers and agronomists are going to have to be more aware of herbicide chemistries, formulations and rotations. While some generics have the same formulation, others are different, and compatibility may be an issue with tank mixes. 

Johnson also cautions that farmers will need to watch recropping restrictions and herbicide rotations to ensure they do not get boxed into a corner with crop rotations or stacked herbicide residues. He also cautions that farmers should not get carried away in trying to invent new application timings. “If you look at a herbicide-fungicide tank mix, just because you can mix the two products together doesn’t mean it is a good idea. The timing of application will likely be wrong for one of the products; either too early for fungicide application or too late for herbicide application,” explains Johnson.

Johnson says that farmers will also have to be careful to observe preharvest intervals.
Glyphosate is the only registered herbicide for weed control at preharvest (Reglone is registered as a desiccant). A grower cannot just throw something else in with glyphosate preharvest. There will be preharvest interval problems, which may result in pesticide residue in the grain. This would have an impact on selling the grain. “It is not a free-for-all, but the policy provides more opportunities for farmers to improve spraying efficiencies,” explains Johnson. “And I think it would be a benefit to the companies if they provide information to farmers so that farmers won’t have to figure out tank mixes on their own.”