Pesticide Tank Mix Order: How to Mix WDG, WP, SC, EC and SL Formulations

Correct pesticide tank mixing is not simply about adding products into water one after another. The mixing sequence depends on how each formulation behaves after entering the spray tank.

WDG, WP, SC, EC, and SL formulations are designed differently. Some products need time to absorb water and disperse, some need to maintain suspended particles, some need to form a stable emulsion, and others need to dissolve completely.

Adding products in the wrong order can lead to:

• Poor dispersion

• Sedimentation

• Flocculation

• Incomplete dissolution

• Emulsion instability

• Nozzle blockage

• Uneven pesticide concentration

A common principle is to add formulations according to their physical behavior, starting with products that require more time to wet and disperse and ending with products that dissolve or mix more easily.

However, there is no universal mixing order that replaces the product label. The active ingredient, formulation technology, water quality, tank partners, and local registration requirements must always be considered.

Why Does Tank Mix Order Matter?

A pesticide formulation is a carefully designed delivery system.

The active ingredient alone does not determine how a product behaves in a spray tank.

Formulation components such as:

• Wetting agents

• Dispersants

• Emulsifiers

• Solvents

• Rheology modifiers

• Surfactants

all influence how the product interacts with water and other pesticides.

When multiple products are mixed together, each formulation needs to perform its intended physical process.

A dry formulation needs to become properly wetted and dispersed.

A suspension concentrate needs to maintain uniform particle distribution.

An emulsifiable concentrate needs to create a stable emulsion.

A soluble liquid needs to dissolve completely.

If these processes happen in the wrong sequence, compatibility problems may occur.

Common Tank-Mix Problems

Incorrect mixing order can contribute to:

The purpose of correct tank mixing is not only to combine products.

It is to maintain a stable spray mixture until application.

How Do Different Pesticide Formulations Behave in Water?

Understanding formulation behavior is the foundation of correct tank mixing.

Different formulation types are designed around different physical systems.

How Do WDG and WG Formulations Behave?

WDG means Water-Dispersible Granule.

WG is the internationally recognized formulation code commonly used for water-dispersible granules.

These formulations contain pesticide particles processed into granules.

When added to water, the granules need to:

1. Become wetted

2. Break apart

3. Release fine particles

4. Disperse throughout the water

WDG does not normally dissolve into a true solution.

Instead, it forms a dispersed suspension.

If WDG is added incorrectly or without enough water and agitation, problems may include:

• Slow breakdown

• Floating granules

• Lumps

• Uneven dispersion

This is why dry formulations usually require early addition into the spray tank.

How Do WP Formulations Behave?

WP means Wettable Powder.

WP contains fine pesticide particles that must become wetted and suspended in water.

The process is:

Powder

↓

Wetting

↓

Particle dispersion

↓

Suspension formation

A high-quality WP should disperse efficiently and maintain acceptable suspension during spraying.

Common WP concerns include:

• Slow wetting

• Powder floating

• Lump formation

• Poor suspensibility

• Settling

Because WP relies on proper wetting and dispersion, it is generally added before liquid formulations that may interfere with this process.

For more information about powder and granule formulation differences, you can also review our guide on WP vs WDG pesticide formulations.

How Do SC Formulations Behave?

SC means Suspension Concentrate.

An SC contains fine solid active ingredient particles already dispersed in a liquid carrier.

After dilution, the formulation needs to maintain uniform particle distribution.

The key performance factors include:

• Suspensibility

• Particle dispersion

• Redispersibility

• Storage stability

• Pourability

SC products are not dissolved solutions.

They rely on controlled suspension technology.

Poor compatibility during tank mixing may cause:

• Particle aggregation

• Faster settling

• Reduced spray uniformity

For a deeper explanation of suspension systems, see our article on SC vs EC pesticide formulations.

How Do EC Formulations Behave?

EC means Emulsifiable Concentrate.

Unlike SC, EC products contain active ingredients dissolved in organic solvents.

When added to water, the formulation must form a stable emulsion.

The process is:

Oil phase

↓

Water addition

↓

Emulsion formation

↓

Uniform spray mixture

EC performance depends on:

• Emulsifier system

• Water quality

• Agitation

• Compatibility with other products

Adding EC too early may sometimes interfere with the wetting and dispersion of dry formulations.

This is why EC products are commonly added after dry formulations have been properly dispersed.

How Do SL Formulations Behave?

SL means Soluble Liquid.

These products contain active ingredients that dissolve in water.

Compared with WP, WDG, and SC, SL formulations are generally easier to incorporate because they do not rely on particle dispersion.

The process is:

Liquid concentrate

↓

Dilution

↓

Solution formation

However, SL products can still interact with:

• Water pH

• Salts

• Other tank-mix products

• Fertilizers

• Adjuvants

Therefore, easy mixing does not always mean unlimited compatibility.

What Is the Correct Pesticide Tank Mix Order?

A commonly used general sequence is:

This sequence is a practical guideline, not an absolute rule.

The final mixing order should always follow:

1. Product label instructions

2. Manufacturer recommendations

3. Compatibility information

4. Local application requirements

Different formulations within the same category can behave differently.

Should WDG Always Be Added Before EC?

In many situations, yes.

The reason is physical behavior.

WDG needs time to absorb water and break apart into smaller particles.

EC needs to form a stable emulsion.

If EC is added too early, the oil-based phase may affect how dry particles interact with water.

Potential problems include:

• Slower wetting

• Poor dispersion

• Uneven suspension

However, this should still be confirmed by the product label and compatibility testing.

The correct principle is:

Add the formulation that requires hydration and dispersion before formulations that rely on emulsification or dissolution.

Why Are Dry Formulations Usually Added Before Liquid Formulations?

Dry formulations such as:

• WDG

• WP

need direct contact with water to begin their physical transformation.

They must:

• Wet

• Break apart

• Disperse

If another formulation changes the water environment first, the process may become less predictable.

Liquid formulations often have different requirements.

For example:

SC requires suspension stability.

EC requires emulsion stability.

SL requires dissolution.

The reason for the mixing order is therefore not simply “powder first, liquid second.”

It is:

Each formulation needs the correct environment to complete its designed physical process.

Does Water Quality Affect Tank Mixing?

Yes.

Water is not only a carrier.

It can influence pesticide behavior.

Important water factors include:

• pH

• Hardness

• Alkalinity

• Dissolved minerals

• Suspended solids

For example:

• High pH water may accelerate degradation of some active ingredients.

• Calcium and magnesium may reduce performance of some herbicides.

• Suspended solids may affect formulation stability.

Before adjusting water conditions, it is important to understand the specific pesticide chemistry.

Our guide on spray-water quality and pesticide performance explains why water pH, hardness, and alkalinity should be evaluated separately.

Can Products With the Same Active Ingredient Be Mixed the Same Way?

No.

This is a common misunderstanding.

The same active ingredient can exist in different formulations.

For example:

An active ingredient may be available as:

• FS

• SC

• WG

• WDG

• EC

These products may have different:

• Co-formulants

• Particle systems

• Solvents

• Surfactants

• Application purposes

A seed-treatment FS product and a foliar SC product containing the same active ingredient are not automatically interchangeable.

The formulation determines how the product behaves in the spray or treatment system.

This is why professional pesticide suppliers evaluate the complete formulation rather than only the active ingredient.

For example, Thiamethoxam formulations may include different formulation types designed for different application strategies. The active ingredient is the same, but the formulation purpose and handling requirements can differ.

What Is a Jar Test and When Should You Use It?

A jar test is a small-scale compatibility test performed before large-volume tank mixing.

It can help identify visible physical problems such as:

• Separation

• Precipitation

• Flakes

• Gel formation

• Excessive sediment

A typical jar test may involve:

1. Using the same water source as the spray operation

2. Adding products in the intended mixing order

3. Observing the mixture after standing

However, a jar test has limitations.

It can show physical incompatibility.

It cannot confirm:

• Chemical degradation

• Biological efficacy

• Long-term storage stability

A mixture that looks acceptable may still have chemical problems.

Common Pesticide Tank Mixing Mistakes

Adding All Products at the Same Time

This may save a few minutes but can create unpredictable interactions.

Different formulations need different physical processes.

Adding EC Before Dry Formulations

Oil-based formulations may interfere with the wetting process of powders and granules.

Ignoring Water Quality

A compatible pesticide combination in one water source may behave differently in another.

Assuming All SC Products Behave the Same

Two SC products may contain different:

• Dispersants

• Rheology modifiers

• Particle systems

Their mixing behavior may not be identical.

Leaving Tank Mixtures Overnight

Some pesticides may lose stability after extended time in diluted form.

Mixing Without Checking Labels

The label remains the final reference for approved combinations and application instructions.

What Should Importers Consider When Building Tank-Mix Product Programs?

For pesticide distributors and private-label brands, tank compatibility is not only a field-use issue.

It also affects product portfolio planning.

Before adding products into a market program, buyers should consider:

A supplier providing multiple formulation options should understand not only active ingredients but also how finished products behave in practical use conditions.

How Should You Build a Reliable Tank-Mixing Strategy?

A practical approach is:

Step 1: Identify the Target

Understand:

• Crop

• Pest

• Disease

• Weed

• Growth stage

Step 2: Check Product Formulations

Determine whether products are:

• WDG

• WP

• SC

• EC

• SL

Step 3: Review Water Conditions

Check:

• pH

• Hardness

• Alkalinity

Step 4: Confirm Compatibility

Use:

• Label information

• Manufacturer guidance

• Jar testing when needed

Step 5: Mix According to Formulation Behavior

Allow each formulation to complete its required physical process.

The goal is not only to combine products.

The goal is to maintain a stable and effective spray mixture until application.

Frequently Asked Questions

What pesticide should be added first in a tank mix?

In many cases, water conditioners are added first, followed by dry formulations such as WDG and WP, then suspension concentrates, emulsifiable concentrates, soluble liquids, and finally adjuvants. Always follow product-specific instructions.

Should WDG always go before EC?

Usually, WDG is added before EC because granules need time to wet and disperse. However, the final sequence depends on the specific products being mixed.

Can SC and EC be mixed together?

Yes, many SC and EC products can be mixed when they are compatible. However, compatibility should be confirmed because different formulations may interact differently.

Do pesticide formulations dissolve or disperse?

It depends on the formulation. SL products dissolve, while WDG, WP, and SC products generally disperse particles in water.

Can a jar test confirm pesticide compatibility?

A jar test can identify many physical compatibility problems, but it cannot confirm chemical stability or field performance.

Mix According to Formulation Science, Not Guesswork

Pesticide tank mixing is more than adding products into a spray tank.

WDG, WP, SC, EC, and SL formulations are engineered differently, and each requires suitable conditions to perform correctly.

Understanding formulation behavior helps reduce:

• Mixing failures

• Compatibility problems

• Spray-quality issues

• Product performance losses

For pesticide buyers, distributors, and users, the most important principle is:

The correct tank mix order follows formulation behavior, not simply the order of products on a quotation sheet.