Call for Order

The recipe to mix glyphosate used to be easy. We added water, AMS (ammonium sulfate) or an AMS substitute, glyphosate and adjuvant -- and hopefully in that order.

That's changing as we move to tank mixes of multiple herbicides and other ingredients. The realities of herbicide resistance are the main driver behind new tank mix strategies. Growers are also adding fungicides and insecticides to the tank in an effort to combine passes.

When it comes to mixing herbicides and adjuvants with water, we can still follow the old W-A-L-E acronym when mixing different types of chemical formulations or solids and liquids. When wettable powders, water dispersible granules, liquid flowables and emulsifiable concentrates are going to be mixed together in a spray tank, you need to add them in the right order.

I was taught to partly fill the spray tank, start agitation and if glyphosate was in the mix, to add AMS or a substitute first. Then, follow the W-A-L-E (Wettable-Agitate-Liquids-Emulsifiable) sequence.

1. Add the wettable powders or water dispersible granules (Dacthal W-75, Diuron 80, metribuzin).

2. Agitate until powders are uniformly dispersed while adding water until the tank is 90% full.

3. Add flowable liquids or suspensions (e.g. Callisto, glyphosate, dicamba).

4. Add in emulsifiable concentrates last (Dual, Warrant, Frontline).

5. Add the adjuvant and top off the tank to the correct volume.

The W-A-L-E sequence still mostly works when mixing two to three herbicides together.

Where it gets tricky is when we add a fungicide, insecticide or other ingredient into the mix. Personally, I've begun to question if there are limits of how much we should be carrying in one batch. Maybe two passes make more sense?

Fortunately, insecticides are either liquid suspension formulations or emulsifiable formulations. Nutrients are typically wettable powders or water-soluble liquid formulations. In theory, if you follow the W-A-L-E sequence, you should still be OK.

Corn and soybean post-herbicide applications are usually not the most opportune time to apply an insecticide, fungicide or foliar nutrient package. So that also limits what we stack together.

I worry about compatibility issues as we mix more products together. How many of you have taken the time to do a jar test to see if products are compatible, or do you rely on the label or reseller for guidance or just dumb luck? I have done the jar test, but it is a bit of a mess, and I don't always know if the result is because products don't mix or some error on my part.

DTN Grains Pro online subscribers also can use the Mix Tank app to plug in the prospective mixture for most modern herbicides, insecticides and fungicides along with various tank additives and get back a proposed mixing order. It's found in the "Toolbox/Mix Tank App" area in the online subscription web site.

Even if products stay in suspension when mixed together, you need to consider if it will impact pesticide efficacy or cause crop damage. For example, you shouldn't mix an ALS herbicide with an organophosphate insecticide -- if you want to use an ALS product, make sure to use a pyrethroid insecticide instead. Organophosphates can inhibit the corn plant's ability to metabolize ALS-inhibitor and some PPO inhibitor herbicides, which can lead to stunted plant growth and "white flash" coloration.

I have learned that I need to keep my product list short. If I follow label instructions and the W-A-L-E sequence, mishaps are few. It helps me to separate herbicides and foliar nutrient applications. There's an advantage to keeping things simple and using a 'stay with what you know' approach.

(PS/GH/AG/CZ)

Copyright 2014 DTN/The Progressive Farmer. All rights reserved.