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Good to be mixed up, in the right order

The sequence of the herbicide tank mix matters. Get it right with W.A.L.E.S

With more interest in recent years in tank mixing different herbicide products to provide more effective control of weeds, and reduce the risk of selecting weeds for herbicide tolerance, producers need to follow the proper mixing procedure.

It’s not just a matter of which products can be safely tank mixed, but also what order different formulations should be added to the sprayer tank, says Darold Niwa, agronomic specialist with UFA, based in Medicine Hat, Alta.

“All herbicide products cover tank-mixing instructions on their labels,” says Niwa. “And most of the major companies have produced very good material that can be found online explaining the process.”

Niwa says a good rule of thumb he recommends for tank mixing is the simple W.A.L.E.S. method. W.A.L.E.S. describes the order in which different formulations should be added to the sprayer tank. Start with half or a full tank of water and follow this order:

W: Wettable powders (all dry ingredients) are added first to sprayer tank water.
A: Agitate thoroughly to ensure proper mixing.
L: Liquid flowables and suspensions are next.
E: Emulsifiers and concentrate formulations are added next.
S: Surfactant solutions are added last.

Niwa says it’s important to check product labels or confirm with herbicide retailers to make sure all active ingredients included in the tank mix are compatible.

“Each herbicide triggers a metabolic reaction inside the plant,” he says. “Depending on the chemistry that can trigger mixed signals which might actually be antagonistic, reducing the effectiveness of weed control measures and/or may even be harmful to the crop.”

W.A.L.E.S to W.A.M.L.E.G.S

Over at BASF they’ve taken the W.A.L.E.S. method a few steps further. Depending on products being used, they recommend the W.A.M.L.E.G.S. mixing order for tank mixes.

That translates into:

W: Wettable powers, flowable products
A: Agitate, anti-flowing compounds and buffers.
M: Microcapsule suspension (a formulation of products used on horticultural crops).
L: Liquids and solubles.
E: Emulsifiable concentrates.
G: High-load glyphosates (products used as pre-harvest aid).
S: Surfactants.

When there is any doubt, Niwa always recommends reading the product label or consulting a crop specialist.

About the author

Field Editor

Lee Hart is editor of Cattleman’s Corner based in Calgary.

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