Unit 4. Pesticide Formulations

Question 1

A pesticide formulation is a combination of ingredients that form an end-use pesticide product. What do we call the component that affects or controls the target pest?

Answer 1

Active Ingredients (a.i.).

Question 2

Some ingredients are added to the pestcide formulation to …
* Improve efficacy (effectivness).
* Dilute the pesticide.
* Make end-use products safer and/or more convenient to handle and store.
* Make them easier to measure, mix, and apply.

What do we call these ingredients?

Answer 2

Inert Ingredients

Question 3

Most pesticides are available in several different formulations and concentrations. When choosing a pesticide formulation, what question should you ask yourself?
1. Do I have the necessary application equipment (ex. a broadcast sprayer)?
2. Is the formulation safe to apply under the conditions in the application area?
3. Will the formulation reach the target and stay in place long enough to control the pest?
4. Is the formulation likely to harm the surface that I plan to treat?
5. Which formulation is most effective?
6. Which formulation is least hazardous to handle, apply and store?
7. All of the above.

Answer 3

7. All of the above.

When choosing between different formulations with the same active ingredient, you ask yourself all of these questions before choosing a formulation. For instance, choosing a formulation that requires equipment that you do not have, makes little sense.

Question 4

What do we call a mixture that has the following properties?
* It does not “settle out” and therefore, does not require agitation.
* It is transparent.

Answer 4

A solution.

Question 5

What do we call a mixture that has the following properties?
* It is formed by dispersing very small particles in a liquid carrier.
* The solid particles do not dissolve in the liquid carrier.
* Particles “settle out” or float on top and therefore, these require agitation.
* Most are cloudy or opaque (cannot be seen through).

Answer 5

A suspension.

Question 6

What do we call a mixture that has the following properties?
* It is formulated by suspending droplets of one liquid in another liquid.
* The active ingredient is dissolved in an oil-based solvent before being further diluted with water.
* Some agitation is necessary to keep it from separating.
* Most have a milky appearance.

Answer 6

An emulsion.

Question 7

Emulsifiable concentrates (EC or E) are a mixture of oil-soluble active ingredient, one or more petroleum-based solvents, and a mixing agent. They are widely used to manage pests for agriculture, nursery, turf, forestry, structural, food processing and public health.

Name two advantages of emulsifiable concentrates.

Answer 7

Advantages:
* Relatively easy to handle, transport and store.
* Easy to pour and measure.
* Little agitation required; will not settle out or separate when equipment is running.
* Not abrasive.
* Does not usually clog screens or nozzles.
* Little visible residue on treated surfaces.

Question 8

Emulsifiable concentrates (EC or E) are a mixture of oil-soluble active ingredient, one or more petroleum-based solvents, and a mixing agent. They are widely used to manage pests for agriculture, nursery, turf, forestry, structural, food processing and public health.

Name two disadvantages of emulsifiable concentrates.

Answer 8

Disadvantages:
* High concentration of active ingredient makes it easy to overdose or underdose due to mixing or calibration errors.
* May damage plants or treated surfaces.
* Easily absorbed through skin of humans or animals.
* Spills are difficult to clean up.
* Many have a strong odor.
* Solvents cause deterioration of rubber and plastic.
* Flammable
* May be corrosive.

Question 9

What do we call liquid or dry pesticide products that are formulated to be used without further dilution?

Answer 9

Ready-to-Use (RTU)

Question 10

Name one advantage and one disadvantage of ready-to-use (RTU) products?

Answer 10

Advantages:
* Convenient to use; no mixing required.
* Some are packaged with an application device.
* Less personal exposure risk due to reduced toxicity and handling.

Disadvantages:
* Limited availability; many active ingredients are not formulated as RTU.
* High cost per unit of active ingredient.

Question 11

What is the term for a formulation that is applied at something close to a 100% concentration of active ingredient (a.i.)?

Answer 11

Ultra-Low Volume (ULV)

Question 12

Name the two classes of aerosol (A) formulations?

Answer 12

Two types of aerosols (A):
* Ready-to-use aerosols usually sold in pressurized, sealed application devices.
* Those sold in unpressurized containers and meant for use in smoke or fog generators.

Question 13

What type of formulation consists of a water-soluble pesticide dispersed in an oil carrier and which typically looks like mayonnaise?

Answer 13

Invert Emulsion

Question 14

Name at least one advantage and one disadvantage of dust (D) formulations.

Answer 14

Advantages:
* Usually ready-to-use (RTU).
* Good when moisture from a spray mix could cause damage.
* Requires only simple application equipment.
* Effective in hard-to-reach indoor areas.

Disadvantages:
* Drift can be a problem.
* May not stick well to treated surfaces.
* May cause irritation to eyes, nose, throat, lungs and skin.
* May clump or clog equipment when damp.
* Some application devices are hard to calibrate.
* Difficult to apply evenly to treatment area.

Question 15

Name at least one advantage and one disadvantage of granule (G) or pellet (P) formulations.

Answer 15

Advantages:
* Ready-to-use - no mixing.
* Low potential for drift due to weight of granule/pellet.
* Lower risk to applicator – no spray, little dust.
* For soil-applied products, weight carries them through foliage to soil surface.
* Applied with simple application equipment.
* Time-release coatings can provide pest control for longer periods.

Disadvantages:
* Application equipment needs frequent calibration.
* Calibration more difficult because released particles are measured by weight (must be collected and weighed).
* Uniform application is sometimes a problem.
* Granules and pellets cannot be used to treat foliage or vertical surfaces.
* May need to be incorporated into soil.
* Generally needs moisture to release the active ingredient so may be less effective during dry periods.
* Pose a hazard to waterfowl and birds who mistake pellets/granules for food.
* Bulky. Low percentage of active ingredient (high percentage of inert ingredients).

Question 16

Wettable powders (WP) are widely-used pesticide formulations with many advantages. Name two of those advantages.

Answer 16

Advantages of wettable powders (WP):
* Effective for most pest problems.
* Can be used in most spray equipment where agitation is supplied.
* Have excellent residual activity (long-lasting control).
* Easy to store, transport and handle.
* Less likely than emulsifiable concentrates (EC) to harm plants, animals, and surfaces.
* Not usually phytotoxic.
* Less risk of skin and eye absorption than ECs and other liquid formulations.

Question 17

List at least two disadvantages of wettable powders (WP).

Answer 17

1. Not easy to measure. Must be carefully weighed out.
2. Not easy to mix.
3. Inhalation hazard when measuring and mixing the concentrated powder.
4. Suspended particles require constant and vigorous agitation during mixing and application.
5. Do not mix well in very hard or very alkaline water.
6. Clog nozzles and screens, suction filters, hoses, and pumps.
7. Residues are visible on treated surfaces.

Question 18

When a wettable powder (WP) is compressed into granule-sized particles, what do we call it?

Answer 18

Dry flowable (DF) or water-dispersible granules (WDG).

Question 19

What is the term for a pesticide that is formulated with food or other attractive substances and left for the pest to find?

Answer 19

Bait (B).

Question 20

What is the name for a pesticide that forms poisonous gases when applied?

Answer 20

Fumigants form poisonous gases when applied and are highly toxic and dangerous to work with. Most require the use of respirators and special equipment to apply and contain the fumigant.

Question 21

Microencapsulated Pesticides (M) are dry particles or liquid droplets surrounded by an engineered coating of plastic, starch, or other material, and once mixed with water, they are applied as a spray.

List advantages and disadvantages?

Answer 21

Advantages:
* Coatings make them safer to handle and apply.
* Easy to mix, load and apply.
* Timed release of active ingredient prolongs effectiveness, reduces number of applications.
* Reduced volatility.
* Reduced risk of odor, staining to treated surface, or plant phytotoxicity.

Disadvantages:
* May require constant agitation in spray tank.
* Risk to bees if microencapsulated product is collected and returned to hive.
* Long restricted-entry interval or preharvest interval due to timed release.

Question 22

Based on exposure risk, in which situation would the handler likely need to use more PPE?

1. Loading/filling granular application equipment.
2. Mixing/diluting liquid concentrate and filling a sprayer.

Answer 22

Most likely number 2 would require more PPE: Mixing/diluting liquid concentrate and filling a sprayer.

Liquid concentrates are usually more toxic than granular formulations of the same active ingredient.
* More handling is required to mix and load the liquid concentrate.
* Granules are ready-to-use and generally have a lower percentage of active ingredient.

Question 23

Sometimes it may be desirable to mix two or more crop production products (pesticides, pesticides/fertilizers) together in a practice known as tank mixing. While this can save time and money, we need to be concerned with compatibility because not all pesticides and pesticide/fertilizer mixes work well together.

List some signs of incompatibility.

Answer 23

• The mix gets hot.
• The mix changes color.
• The mix forms gases or precipitates.
• The mix forms a soapy scum at the surface.
• The mix forms a gel or a sludge.

Question 24

If you have read the labels of the products you plan to tank mix and they provide no guidance on product compatibility, what should you do to test for product compatibility?

Answer 24

To test for tank mix compatibility:
1. Put on PPE. Consult the label for PPE recommendations and always use the strictest recommendations.
2. Use a large, clean, clear jar to contain the test mix.
3. Add water and each of the products in the same proportions as you expect to use in the tank mix.
4. Use the W-A-L-E jar test mixing order.
5. Add diluent (ex. water) first.
6. Add Wettable powders, other powders, or dry-flowables first to form a slurry.
7. Agitate well.
8. Add water-based Liquids.
9. Add Emulsifiable concentrates (EC).
10. Add any other non-aqueous components such as crop-oil, oil-based anti-foaming or drift control agents.
11. Shake for 10 minutes and let stand for 15 - 30 minutes.
12. If you see signs of incompatibility, redo the test and try adding a compatibility agent in the step where you first add water to the jar.

Question 25

A product label bears the name Alpha 40 WP. What can you tell about the product?

Answer 25

“Alpha 40 WP” is a wettable powder (WP) and is 40% active ingredient.

Question 26

A product label bears the name Beta 80 DF. What can you tell about the product?

Answer 26

“Beta 80 DF” is a dry flowable (DF) and is 80% active ingredient.

Question 27

An adjuvant is a chemical that is added to the tank mix, usually to make the pesticide work more safely or effectively.

Which of the following is a type of adjuvant?
1. Wetting agents.
2. Drift control additives.
3. Safeners.
4. Stickers.
5. All of the above.

Answer 27

5. All of the above.

There are many types of adjuvants. All of those listed are commonly used.

1. Wetting agents. These are added to wettable powders (WP) to cause the powder to be more easily mixed with water.
2. Drift control additives. These increase droplet size and thus, help reduce drift.
3. Safeners. These reduce the toxicity of a pesticide formulation making it easier to handle or less likely to damage the treated surface.
4. Stickers. These allow the pesticide to stick to the treated surface.

A list of common adjuvant types is found on pages 4-20 and 4-21 of the Core Manual.

Question 28

What is a surfactant?

Answer 28

A surfactant is a type of adjuvant that alters the way that a spray droplet interacts with a treated surface. Typically, that treated surface is a leaf surface. Since leaf surfaces often have a waxy coating, spray droplets are not able to make close contact with the leaf surface. By changing the way that the spray droplet interacts with the leaf surface, the pesticide can act more effectively.