Mixing, Loading, and Application Copy


Learning Objectives:

Learn how to protect water sources near mixing sites. Know what kind of protection you need for loading and mixing. Name types of empty pesticide containers and what to do with them, i.e. can they be rinsed and re-used? Learn how to decide if pesticides can be mixed together safely. Understand when you may need more personal protective equipment. Know what to do when you are done mixing, loading and applying pesticides. Describe personal cleanup and what do with rinsates from equipment cleanup. Understand when pesticide collection systems are necessary and what the advantages are of them. Be able to describe, “closed system mixing and loading” vs. “enclosed application systems.”

For pesticide applicators, the most dangerous part of the job is mixing, loading and applying chemicals. Though you may know a chemical well, never assume that every job is the same or will require the same precautions. In fact, you should always read labels, even on a product you have purchased before as safety precautions are constantly being updated.

Applicators are usually exposed to harmful levels of pesticide while they mix and load concentrates. It presents a great risk of poisoning. If you take time for safety, you will reduce this risk.

Before you begin, always choose a well-lit and well-ventilated area. Your mixing location should also be far from any people, animals, food or other pesticides that could be contaminated.

Also before mixing, ensure that you have set up your mixing area to prevent contaminating water sources. Keep any pipe or hose you may use above the level of the pesticide mixture to keep them from contamination if there is any back siphoning. When you have to pump water into a tank for mixing, use an anti-siphoning device, backflow preventer, or a check valve. Law may sometimes require this.

Do not mix or load where spills or leaks could overflow into a water source. If you have to use water from any water system, including ponds, streams, wells or faucets, extra safety measures are essential. Mixing equipment has to be kept where spills and leaks will not reach the water supply. If you know you will be mixing at the site often, install a collection tray, grade the soil, or install dikes.

Before you even open a pesticide container, be sure you have on the appropriate amount of protective equipment. It is required by law that you wear what a pesticide label instructs you to wear. Many times you will want to wear more protective gear than what is recommended.

Aprons are excellent protective gear if you may be splashed during handling activities. They are effective if you will be leaning on or against any mixing containers. Choose aprons made of nitrile, butyl, or foil-laminated materials. Aprons can keep pesticides off the front of your clothing, are cooler than chemical-resistant suits, and are easily removed.

Face shields are appropriate when splashing of liquid pesticides is possible or when dry formulations could send dust into your face and mouth. When you choose a respirator, safety goggles are more appropriate.

A dust/mist filtering respirator is necessary when working for long periods with dusts that can waft easily. Be sure to use those approved by NIOSH/MSHA and use them with goggles to protect your eyes.

A vapor-removing respirator (approved by NIOSH/MSHA) is needed with any chemicals that produce vapors harmful to your nose, throat, and mouth.

Always open cardboard containers with a sharp knife that you only use for this purpose. Clean it each time. Open containers only on a level, stable surface and prevent the container from tipping or leaning to avoid spills.

If you have to pour a pesticide, keep the containers below face level to avoid splashes into your eyes or mouth. When working outside, particularly with dusts, stay out of strong currents. For siphoning, never start the siphon with your mouth.

Avoid spills by always closing pesticide containers tightly after each use, even if you will use it again soon. While filling, never leave a tank unattended. If you do spill pesticide, stop what you are doing and remove contaminated clothing and protective equipment. Wash yourself with mild detergent and water quickly. Only clean the spill after you are clean and have on clean protective equipment.

Once you have emptied a pesticide container, it will still contain enough remnants of pesticide to be dangerous to you or others. For this reason, never leave empty containers on site or give them to anyone for any reason. If you can rinse them, do so as soon as possible. Return them to your storage site. If they cannot be refilled, recycled, etc., crush them and dispose of them according to the law.

If for any reason the container cannot be rinsed, empty them as best you can. For liquid concentrates, tap the container while allowing it to drain for at least 30 more seconds. Return these containers to the manufacturer, if recommended.

When you are diluting a pesticide, rinse the containers (unless labeling advises against it). The sooner you rinse the containers, the easier it is to remove all of the residue. This is also a money-saving technique as the residue can be added to your mixture.

Once containers have been thoroughly rinsed, they can be disposed of as nonhazardous waste. Be sure to mark them as such. All containers that can be rinsed should be pressure rinsed or triple rinsed. The best liquid for this is the diluent used according to the label.

Some pesticide equipment allows you to pressure rinse the container by inserting high-pressure nozzles into the container and rotating it to rinse for 30 seconds or more. It will also allow you to drain any remaining mix into the mix tank. Some systems work by puncturing the container to insert the hose while others just use the container’s opening.

In order to save time, money, and fuel, applicators often mix more than one pesticide for application. Occasionally manufacturers will pre-mix them. It is legal to mix them yourself, unless labels specifically instruct you not to mix a particular chemical. The chemicals being mixed must be compatible to prevent undesired effects like loss of effectiveness or chemical reactions that will damage surfaces or equipment. Charts that tell the compatibility of chemicals are available in pesticide trade publications, through the Cooperative Extension service, and industry recommendations.

If chemicals are not compatible, they can form lumps, gels or even separate. Any of these circumstances negatively affects your ability to apply the pesticide. Other effects are those you cannot see but will result in increased toxicity, loss of effectiveness against the pest or injury to a surface.

If you are unable to find whether two chemicals are compatible, mix a small amount first to use as a test. Before you proceed, be sure to put on enough personal protective equipment, including gloves, eyewear and apron. Use a clean, clear glass container and be sure to use the same diluents and amounts as will be used later. Unless there are other directions from the label, use the W-A-L-E plan.

  1. First add some diluent.
  2. Next add Wettable and other powders or Water-dispersible granules.
  3. Thoroughly Agitate and add any more diluent.
  4. Add the Liquid products.
  5. Finally add Emulsifiable concentrates.

Shake the jar after adding all the ingredients and feel the sides to see if a chemical reaction is causing it to produce heat. If so, they probably should not be combined. Check the mixture 15 minutes later for heat.

If the mixture forms clumps or develops surface scum or solids settle out, these chemicals should probably not be mixed. If there are no signs of problems, test the mixture on the target area.

When you apply pesticides, it is your responsibility to protect yourself, others, and the environment as well as apply the pesticide correctly.

Remember, it is the law to wear equipment consistent with what is recommended on the label. Survey the situation to decide if you need more than what is recommended.

For hand-held applicators like shake cans, there is a chance of direct exposure through dripping or clogged nozzles or unfastened caps. Protect the area of your body in contact with the equipment.

When carrying equipment on the front of your body, use an apron. If the equipment goes on your back, consider a cape. If you carry only the nozzle, use something to cover your arms and hands. Each of these pieces of protective equipment can protect you from leaking or drippy equipment.

Any time it is possible, do not walk or drive into a treated area. You should always back into an area, away from where the pesticide is released. If you are unable to, wear protective footgear, like shin or knee-high boots as well as chemical-resistant pants. It is also helpful to cover your clothing with a spray starch or fabric stain remover to provide an extra barrier. This will also make cleanup easier.

In a vehicle, be sure you are in front of and above the area where the pesticide is released. If you have to enter the area where it is still suspended in the air, consider a rain suit or apron as well as respirator and goggles.

At certain times you can be exposed to pesticide fallout. During these circumstances, it is possible to be completely drenched and engulfed. This will result in large amounts of residue on skin and clothing and will pose a serious hazard. This can happen when you are doing a mist blower or air blast application, applications with high-pressure sprayers and power dusters, aerosol and fog applications, applications to trees, roof eaves and canopies, and aerial applications. For these situations, wear more protective gear than is recommended. Chemical-resistant suits with hoods, gloves, footwear and full-face respirators are essential to fully protect you during these high-exposure scenarios.

Some situations may require the use of a respirator when you would not normally wear one. If you are performing an application in enclosed spaces like truck cargo areas, elevators, and grain storage units and so forth, a respirator may be your only protection against inhalation injury.

Other application situations require specific care for your protection:

  • If it is necessary to adjust your equipment during application, consider extra protective gear.
  • When using application techniques that require hand and arm submersion into liquids or dusts, wear a sleeved apron as well as protective footwear and a facemask.
  • If you are applying into a wind current, be sure to use extra protective equipment, including eyewear and a respirator.
  • While mixing, loading and applying ultra-low-volume concentrates and fumigant formulations, wear extra gear, as the active ingredients are high and toxic.


Each time you begin a pesticide application, follow these specific steps to ensure your safety.

  1. Be sure the pesticide reaches its target. If it does not, it can be harmful, as well as a waste.
  2. Check the delivery rate. Watch for puddles or dry spots in the application area. Concentrate on areas where you change directions or pause. Check your work early on so that you can adjust your equipment to the correct proportion, if necessary.
  3. Consider the appearance of the pesticide. Does it look like it should? Powders will have a white appearance while granules should look dry and emulsifiable concentrates look milky. Make sure your mixture is blended correctly. Also be sure the surface material is not reacting to the pesticide.
  4. Watch out for nontarget organisms. Make sure all people and animals are offsite before you begin. (This is the law!) Check labels to see how long before people and animals can return. If there is no indication, be sure they wait at least an hour.
  5. Stay away from nontarget surfaces. If it is possible, remove any items that can be contaminated during treatment. For those that cannot, be sure to cover them sufficiently. It is important to cover or remove any food or utensils, pet food, water supplies, toys and bedding.
  6. Use your equipment safely. If you have to pause or stop for any reason, turn off your equipment. Be sure to release pressure on any pressurized tanks. Keep people and animals away from the equipment. Be sure to check all equipment parts occasionally and keep yourself protected while checking equipment.

After you have completed mixing, loading, and application, take time to finish the right way. This means washing your equipment and yourself. Store equipment and all materials used safely and appropriately. Make sure your work site is clean and free from any residue or debris. Don’t leave the site unattended and be sure to accurately record what you applied and the conditions during application.

When a job is complete, proper equipment cleaning is necessary and should be done as soon as possible. Try not to always clean equipment in the same location, as it is easy to have a buildup of pesticide residue that can increase chances of harmful effects to handlers and others in that area. Only adequately trained workers should clean equipment as it is essential to do it right to prevent contamination. Protective gear is necessary for cleanup, just as it is for mixing and handling.

Cleaning correctly is safe and it will also keep your equipment functioning properly for longer periods of time. Any unused pesticide should not be stored for extended periods in your applicators. They will separate, corrode or clog your hoses and reduce their effectiveness. This will result in more money spent for equipment repair or replacement.

When equipment is cleaned, use cleaning agents, water or the diluent used in the mixture. Make sure you collect the resulting liquid (rinsate) from the cleaning procedure. You will want this amount to be as limited as possible to prevent unnecessary disposal. Wash any vehicles that carry pesticides, particularly those that will be used to transport family or others who are unprotected. It is possible to be poisoned from residue on such vehicles.

Any rinsates created during cleaning procedures can harm people and animals. They are also extremely harmful to water supplies like lakes, streams, wells, etc.

Rinsates can be used as a diluent for future mixtures if,

  • Pesticide contained in the rinsate can be used on the new target site.
  • The new pesticide product and the amount of pesticide in the rinsate do not exceed label recommendations.
  • The rinsate is used as a diluent with a compatible pesticide
  • You comply with any label specifications on new pesticides.

You cannot add a rinsate to a mixture if,

  • It is not listed as an acceptable diluent on the label
  • It contains strong cleaning agents that can harm application surfaces, plants or animals.
  • The rinsate would alter the pesticide mixture.

When it is time for you to clean up after application, take extra precaution. Before removing any equipment, wash the outside of your gloves. Next, carefully remove any protective gear and try to keep residue away from your skin. Take a shower! If you are unable to do so immediately, wash your arms, face, hands and any other exposed areas. As soon as possible, shower and wash your hair thoroughly. Finally, keep family members and pets away from contaminated clothing until they can be cleaned appropriately.

Keep in mind that keeping adequate records will save you time and money as well as make you a more efficient applicator. Record keeping allows you to see patterns of pesticides and how they work in different situations. It helps you pinpoint problems and protect yourself against accusations of misuse. They will help you purchase only what you need and what is most effective for your business.

Establish early all of the necessary information you would like to track. The more specific information you collect, the more effective it will be. Come up with a standard form you can use in all situations. Be sure you have plenty of copies handy. Some information you will want is: names of anyone involved in the application, time and day of application, location and description of site and conditions, surface that was treated, target pest, equipment used, pesticide used including brand and common name, formulation, active ingredient percentage and EPA registration number, amount used, diluent amount, rate of application and size of treated area.

Include space for notes on that particular job. Take note of anything unusual or anything you may need to know for future applications. Keep notes on any monitoring and what is and isn’t successful.

Sometimes the state or local authorities require that you keep records. When this is the case, be sure you are aware of what they require. It may be necessary for you to show your records at a later date.

Safety systems like closed mixing and loading systems, enclosed application systems and pesticide containment systems, are investments that pesticide handlers should consider. They are excellent for handlers who handle large amounts of pesticides or who handle pesticides that are dangerous. Occasionally these will be required, not optional.

Some products will require the use of a closed mixing and loading system. These are designed to keep pesticide from coming in contact with handlers during these processes. This is the case with pesticides that can cause acute and delayed effects. Labeling will warn you of these situations. Sometimes a state will require their use.

There are two types of the closed mixing and loading systems: those that use mechanical devices to move the pesticide from container to equipment and those that use soluble packaging.

A mechanical system uses equipment that can remove the pesticide from its container, transfer it, rinse the container, and put it into the application equipment. Generally they are for use only with liquid formulations. They are often custom made and use commercial parts. Unfortunately, they cannot be used with all pesticide containers due to the variance of shape and size.

Mechanical closed mixing and loading systems move the concentrate either by gravity or by suction. Sometimes gravity systems are referred to as “punch and drain systems.” In a gravity system, an unopened container is placed inside of a chamber and is then sealed inside. The material is drained into the mixing tank once a punch has cut a hole in the pesticide container. A nozzle that is attached to the punch can then rinse the interior of the container. This allows the rinse to flow into the mix tank as well. The pesticide container can then be disposed of. You can only use this type of system with a full container. It can be used with dry concentrates as well.

A hose and pipe combination are used to move pesticides in a suction system. Some pesticide containers have a built-in probe that is inserted. These can also rinse the container and transfer system and rinse water will be mixed in as well. If you are not going to use all of the pesticide in the container, the system must have a way to measure the amount that is suctioned. Some of these systems will not allow you to reseal the container and they are also difficult to use if the solution is highly viscous.

Soluble packaging allows the handler to just place the entire package into the mixing tank where the container will dissolve. The negatives include accidental pesticide release if the package is exposed to water and a high risk of splashing when adding the package to the tank.

Closed systems may allow for less protective gear during activities. Substitution of long-sleeved shirts and pants for personal protective equipment may be possible. Chemical-resistant gloves and aprons may be necessary if the closed system is used for concentrated pesticides. Eyewear may be needed if the system is being used under pressure.

Even if you choose closed systems, you should keep protective gear available at the site. This is in case of a mechanical breakdown or spill.

An excellent way to reduce exposure during some application is by the use of an enclosed application system. These involve an enclosure that completely surrounds you and prevents contact with the pesticide. These systems include, an enclosed cab, enclosed cabs with air filtering ventilation systems, enclosed cabs with vapor-removing ventilation systems and enclosed cockpits. Each of these may allow you to wear less personal protective gear. However, you should have the gear with you in the enclosed system. You may have to get out during application and the gear would be necessary. If you get out during application, be sure to remove the gear before you get back in. It should then be stored either outside of the cab or in a tightly sealed container that you can take with you.

If you know you will usually be mixing and loading at one site, it is good to invest in a pesticide collection pad or tray. They can catch any overflow, spills, leaks, etc. You can wash them with water and recover the lost pesticide for re use or disposal. Some of these are small enough to be portable while others are larger and require installation. In the long run they will save money and help protect the environment. They reduce waste and protect the mixing and loading area more efficiently.

Sites where only a small amount of pesticide is mixed and loaded are good candidates for a collection tray. It should be made of chemical-resistant rubber or plastic. It should also have a rim to collect the leaks and spills, as well as a spout to pour out contents. Trays are smaller and more portable.

Collection pads are better or sites where large quantities of pesticide are handled. Often this will be outdoors or in a large, open building. The pad has to be made of waterproof material. Porous surfaces are unacceptable. The pad should also be concave and have enough room to handle a large amount from spills or leaks. An automatic sump system or manual pump are also essential to recover the lost material. This pad should be placed out of the way of irrigation or rainwater to prevent overflow. It would also have to be washed out every day after use.