mixing and loading

Proper Mixing and Loading of Pesticides

Daniel CooperCEU

mixing and loading
UF/IFAS photo

By Amir Rezazadeh

Editor’s note: This article grants one continuing education unit (CEU) in the Core category toward the renewal of a Florida Department of Agriculture and Consumer Services restricted-use pesticide license when the accompanying test is submitted and approved.

The primary pesticide handling tasks are mixing and loading. These are also the most harmful aspects of pesticide application. Because of the concentrations and amounts of pesticides involved, unintentional leaks at a mixing and loading site form a significant danger of ground and surface water pollution.

Mixing and loading pesticides exposes handlers to the products’ highest concentration and increases the risk of contact. To prevent contamination and protect human health, pesticide mixing and loading, as well as equipment washing and rinsing, should be done in a safe and environmentally responsible manner. All workers who handle, mix or load pesticides must be trained as handlers or hold a pesticide license.


When mixing and loading pesticides, as well as cleaning equipment and pesticide containers, avoid contaminating water sources. Pesticides should not be mixed or loaded near any private or public drinking water supply or surface water.

It is essential to have a back siphon prevention mechanism in place before filling any pesticide application equipment or mix tank directly from a water source. Prevent the back-siphoning of pesticides into surface water impoundments or wells.

For all mixing and loading operations, a discharge containment surface that has been appropriately designed should be utilized. Ensure that no point pollution occurs due to pesticide concentrates, mixtures or residues; safeguard all resources. Disconnecting hoses from injection ports on chemigation systems requires extreme caution to prevent pesticide leakage.

When adding water to the device, take extreme caution to prevent overflow. Never leave equipment alone when it is being filled.

Open pesticide canisters with caution. To open paper items, use a knife (designed specifically for pesticide usage) rather than tearing them open. To avoid exposing your face to liquid, keep the container below eye level when pouring. Use a pump to extract the concentrate from a big container. Immediately put partially filled containers back into storage after closing them. After emptying a container, wash it under running water and transfer the watery residue to the tank for application.


Select the pesticide mixing and loading area with caution. The location should be outdoors or in a well-ventilated area, ensuring a safe distance from individuals, animals, food, other pesticides and potentially contaminated objects. Select a location with adequate light, particularly if working at night. Exercise caution when handling insecticides indoors, ensuring that appropriate lighting and ventilation are present to prevent any potential mixing or loading accidents.


All personnel engaged in mixing and loading activities must wear personal protective equipment (PPE). Put on the proper PPE before opening a pesticide container. It is required by law to wear all items of PPE specified on the pesticide label for loaders and mixers. In some loading and mixing situations, think about wearing extra PPE. Protective eyewear (goggles, glasses or a face shield), chemically resistant headgear, aprons, gloves, shoes, long-sleeved coveralls, socks, a first-aid kit and respirators should all be readily available outside the storage area. Having access to an eyewash station that can flush the eyes for 15 minutes is also important.

Due to the hazardous nature of pesticides, do not work alone. If you splash or drop pesticides on your clothes, stop working immediately and remove the contaminated clothing. Wash the clothes thoroughly with soap and water separately from other clothes. This is necessary to prevent contaminating other clothes.


Prepare for handling unexpected situations. Your emergency-response plan should include:

  • A complete inventory of all pesticides currently in use or stored, including their names and amounts
  • Detailed directions to the site of the project on a map
  • Important personnel and owner contact information (name, address and phone number)
  • The facility plan should include pesticide sites, flammable products, electrical service, water supply, fuel storage tanks, fire hydrants, storm drains and nearby wetlands, ponds and streams.
  • Location of emergency equipment supplies, such as breathing apparatus and protective equipment

The purpose of the mixing and loading pad is to capture any leaks or spills that may occur because of inadvertent spills or overflows from application equipment. While spray solutions are being moved to or from the batch mixing equipment, car and pesticide or fertilizer storage area, they are parked on the mixing and loading pad.

Make sure you select a mixing and loading pad that is designed appropriately. There are a variety of pads to choose from, such as concrete pads, tarps or portable rubber pads. Based on your specific circumstances and requirements, pick the one that best suits you.


The dilution and mixing of chemicals might vary depending on the mode of application and the formulations of the products. It is advisable to mix the ingredients in the subsequent order of importance:  1) water, 2) pesticides, 3) additional substances and 4) the remaining water. Before adding anything else, dissolve any suspending agents in the water and agitate the mixture for 15 minutes. When it comes to aerial applications, the person in charge is responsible for the task of combining and loading chemicals.

For chemigation, it is not advisable to inject liquid pesticides into the irrigation system directly from the container. To ensure that the pesticide is delivered uniformly to the irrigation system, keep the chemical tank agitated continuously. Agitation (shaking with a stick paddle) is especially critical for materials with low solubility, such as chlorothalonil.

  • Use personal protective equipment.
  • If feasible, work in pairs. The ability to communicate via radio is an advantage.
  • Before you start to mix, make sure the pump is working.
  • Mix in a place with good air flow.
  • Make sure you have good lighting.
  • When mixing, be sure of your balance.
  • When pouring, move the jug to the side to reduce stuttering delivery.
  • Pour pesticide down the tank’s inside side to reduce splashing.
  • Do not immerse the water supply hose in the pesticide solution.
  • A check valve is legally mandated to prevent backflow from occurring in water supply hoses.
  • Transfer the rinse water to the bog by placing the measuring cups, jugs and mixing stick into the tank.
  • Make sure to wash your gloves before removing them.

Sources: Mixing, Loading, and Application of Pesticides and Pesticide Mixing and Loading  

Amir Rezazadeh is a multi-county fruit and field crops Extension agent at the University of Florida Institute of Food and Agricultural Sciences St. Lucie County Extension office in Fort Pierce.

To request a hard copy of the article and test, or if you have questions regarding this article, test or CEUs, contact Amir Rezazadeh at amir2558@ufl.edu or call (772) 462-1628. Please allow two weeks to process your CEU request.