Safety in Mixing
It's important to mix chemicals in the right order if you want to minimize the risks to you and others, your crop and your equipment.


Mixing Pesticides and Other Chemicals

When they're mixed properly, the spray solution will work just as it should when applied to the target area without the risk of drift, runoff and harm to people, wildlife and nontarget plants.

Mixing things properly minimizes reapplications and decreases the costs involved in the process.

Or will it?

Just because you mix in the ingredients doesn't mean the final solution will act the way you want it to.

When you add chemicals and additives to your spray tank, the formulations may change as they mix together. The overall dynamics may change, which means you'll need to add the ingredients in a specific order to avoid problems.

What Happens in the Spray Tank?

What happens in Vegas stays in Vegas? Maybe. But what happens in your spray tank may definitely stay in your spray tank depending on what was added and how it was mixed.

What do we mean by that?

Back in the day, farmers used to test ingredients in a Mason jar and then use a spoon to mix them all together. Sometimes the mix would look like curdled milk. Other times it looked like jelly.

This meant that they added the ingredients in the wrong order.

Now if the solution came out whitish or clear, maybe even translucent, they knew it was mixed correctly.

Today, no one is really using Mason jars and spoons to find the correct order of ingredients. They use mixing inductors to find out how the solution will act in the spray tank.

So if you mix things incorrectly and the solution turns to jelly, what do you think will happen to your equipment? Precisely. It will gunk up the hoses and stay in the tank, causing malfunctions down the road and interfering with future mixes.

You don't want to be the applicator who blindly dumps in chemical herbicides and adjuvants and other additives without knowing exactly what you're doing. This can result in unexpected and terrible applications.

The solution may drift. It may cause more harm than good.

Why Read the Safety Labels?

Pesticides, fertilizers and chemicals in general... they're not a desk you bought from Walmart and can look at the picture to see how it's put together.

There are labels on these products for a reason.

The safety labels have important information about many different things, such as:

  • How to protect yourself from chemicals
  • The timing, rates and application sites
  • How to manage the solution during application
  • Which chemicals are compatible and incompatible

Some products work better when applied during certain times of day. Some products may need to be mixed a certain way while others need to be used without additives.

You may have purchased a product that you think will combat ants, but it doesn't work as well on that particular species.

Anytime you use a pesticide, a fertilizer, a plant nutrient or any other product, you should always take the time to read the label.

Go through it with a fine-toothed comb. Otherwise, you could cost yourself time and money. p>

How to Mix Products Correctly

Let's try this with an example:

Say you want to knock out those invasive weeds in your cornfield. You've decided on the herbicide Atrazine 4L to control grass weeds in corn, an anti-drift agent like Border Xtra to keep the solution from drifting to nearby crops, and then maybe a 2,4-D low-volatile herbicide to target woody plants and broadleaf weeds.

Now what if you want to add a little glyphosate to the mixture just for some added potency? Maybe Roundup, for instance.

You might think that Roundup would go in the spray tank first, followed by the other herbicides and adjuvants. After all, Roundup is the most potent herbicide, so it'd have to go first, right?

No, not at all.

The products might look fine based on the random order you mix it in. That is until you add it all to water. Then it might start to turn to gel as it enters the sprayer.

You don't want that.

There's an order here based on the previous products:

  1. Atrazine
  2. Border
  3. 2,4-D
  4. Roundup

It makes a big difference in how you add the chemicals to the tank. That's why it's so important to conduct a mix test before you place all the products in your equipment.

This mix test will most always be suggested on the label. That's another reason you should always read the labels before using the products in the field.

The Basics of Mixing Products

It all comes down to order and amount.

Mixing improperly is going to cost you a lot of time and money. Not only will you have to spend more money because of wasted products, but the extreme growth of some weeds during that time can decrease your yields and profits.

Just as combining ingredients in the right order is important, so too is adding them one at a time. So many applicators want to dump all the products together in the tank without taking the time to do any tests.

Not only that, but they want to mix different products together, such as combining an insecticide with an herbicide and a fungicide.

It might be okay in the smallest percentage of situations, but it's not a recommended practice. Why?

Every product belongs to a specific chemical class. Some classes aren't always compatible with other classes. The classes may also have different droplet sizes, which may not work when you're combining a fungicide with Roundup because of the size of their respective droplets.

Something like Roundup with glyphosate has thin, rough droplets that penetrate and move through the weed. It's not necessary to cover the entire plant because of its systemic nature.

Now take a fungicide for an example. It has fine droplets that need to coat the plant evenly in order to protect the crop more effectively from diseases. Fungicides are also known to drift, so you may need to add an anti-drift agent to the mix as well.

Do you see where we're going here? Mixing Roundup with a fungicide might sound like you're tackling two things at once and saving time in the process, but you're really only causing more problems.

You can't have both. You can't hardly coat a weed while needing to fully coat your crop at the same time with the same mix. Do it the right way, and apply each product class separately as needed.

Here's a basic mixing guideline to follow when you're adding them to the spray tank:

  1. W - Water or conditioners first. Fill the tank to at least 1/4 full, and begin agitation. Your compatibility agents will follow.
  2. W - Water-soluble packets (WSP). These go into clean water before you add any other products.
  3. W - Wettable powders (WP). These go next.
  4. W - Water-dispersible granules (WDG). Follow the order with these.
  5. A - Agitate the mixture, and continue agitating while spraying. Make sure the products have mixed fully before adding the next product.
  6. L - Add any liquid flowables or suspension concentrates (SC). You'll also want to add more carrier at this time.
  7. E - Add your emulsifiable concentrate (EC or MEC), and completely fill the spray tank with water.
  8. S - This is the point where you add your surfactants and adjuvants.

Following this outline will ensure that your tank is fully mixed and you don't have any separation or reaction of the products that could adversely affect the application.


Ignoring the safety labels and mixing chemicals improperly is one way to ruin the application. Mixing requires a certain order to ensure a proper application, and reading the labels beforehand can help you become a pro and have a better understanding of what you're using and how to use it properly.


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