Know your tank mixes to avoid incompatibilities with sprayers, products

Jar tests, reading the label and asking trusted advisors are good steps

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Farmers need to know whether the products they’re putting into their sprayer tanks will get along or whether they risk plugged nozzles, crop injury and reduced weed control, provincial extension advisors warn.

Mike Cowbrough, weed specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs, and Jason Deveau, application technology with OMAFRA, suggest farmers review products before mixing as some tank mixes are incompatible and can create biological and physical problems.

Cowbrough and Deveau spoke to farmers at the Farmsmart Expo held July 11, at the Elora Research Station.

Why it matters: Mixing incompatible products can create expensive consequences, including crop injury, poor product performance or plugged equipment.

Biological incompatibilities

Are the crops able to handle the chemistry of all products mixed together?

Mike Cowbrough.
photo: Jennifer Betzner

“What’s the risk of a plant sprayed with a mix of four, five or six things together? Especially the way plants tolerate herbicides through metabolism and now it has to metabolize five things instead of one. This can increase the crop injury,” says Cowbrough.

Antagonism can pose a risk — one product tying up another, stopping it from doing its job.

“Increase crop injury and decreasing control, that’s not what you want to have happen,” says Cowbrough.

As well, if the efficacy drops, the farmer won’t be saving much time.

“You may never know that your product wasn’t as good as you thought it was, or you get no control at all; in an effort to save time and trips you find yourself spraying again to correct the problem,” says Deveau.

Physical incompatibilities can be quickly found when a sprayer plugs due to two liquids forming a solid.

As well, undissolved or unsuspended material can slowly plug sprayers, which can also happen when the farmer isn’t applying the correct rate.

“When looking at a product like Marksman, it takes a fair amount of agitation to get it back into full solution, and imagine mixing five products like that together. You need quite a bit of agitation,” Cowbrough said.

For other products, such as Valtera, the label specifically states the need to use product within six hours. Otherwise it adheres to plastic and rubber lines.

Jason Deveau.
photo: Jennifer Betzner

“Some residues are sneaky. Certainproducts form a film inside the tank. You won’t see (it), it gets coated and sticks around,” says Deveau. “The right products can break it loose, it comes off in sheets, it plugs everything or it leads to carry over — products that shouldn’t be in certain fields at certain times suddenly are.”

Growers are beginning to use dry products more often. These tend to be more particular to the water volumes in which they are dissolved.

When looking at the common product Sencor 75DF, usually paired with Eragon and glyphosate, the product dissolves better in some water volumes, compared to others.

“We have pretty much full dilution of the product at 20 gallons per acre, but as we move to lower volumes, 10 or five gallons per acre we have a lot more sediment left over,” says Cowbrough.

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As well, water properties can be a concern.

Sencor 75DF showed it dissolves better in 15 C water compared to 5 C.

“If it’s not dissolved in solution, it’s not hitting the target and imagine how plugged the filters would get,” says Cowbrough.

Check product compatibility

There are many sources for information about product compatibility and water considerations. Start by reading the label, even though it is sometimes complicated.

Cowbrough suggests using the Pest Management Regulatory Agency label search database.

“If there’s nothing sufficient in the label, that’s when we want to talk to the manufacturer. They have the most expertise for those products,” says Cowbrough.

Deveau suggests completing jar tests on a yearly basis to ensure the mix is continuously efficient, even if it’s a common tank mix.

They help to showcase, on a smaller ratio, the success of tank mixes before using them in your sprayer.

“Formulations have changed and no one calls to tell you that — the jar test is for you to get a little surprise before you get a big surprise,” says Deveau.

It’s best to keep jar tests all season long.

Having to cancel a spray job due to weather conditions, forcing product to sit for several days, may raise questions about efficacy later.

“If you have the jar test, leave it around and see what happens. If it sits for three, four or five days — see how well it can get back into solution,” says Cowbrough.

Deveau suggests pre-fabricated kits, such as the one from Precision Labs.

The kit includes a pipette with marks for different rates of products and instructions on how to perform the procedure.

About the author


Jennifer Glenney

Jennifer lives on a farm in Cayuga, Ontario and has a lot of experience in the many aspects of agriculture.



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