Using Pesticides

Table of Contents

What are pesticides?Are pesticides safe?How do you use pesticides appropriately?Preventing Pesticide Resistance Resources

What are pesticides?

The term “pesticide” is a generic term for any substance that is used to control, prevent, kill, suppress or repel pests. There are many different types of pesticides including herbicides, insecticides, rodenticides, fungicides, and others.

In the United States, the distribution, sale, and use of pesticides are regulated under a federal law known as the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and any pesticide that is distributed or sold in the US must be registered by the Environmental Protection Agency (EPA).

At Teton County Weed & Pest, we use two types of pesticides (herbicides and insecticides) in our programs, and we sell select herbicides to the public.

Are pesticides safe?

Pesticides are neither inherently safe nor inherently dangerous. Like all chemicals, the risk associated with a pesticide is dependent on the toxicity and the amount of exposure. This applies to both synthetic and organic pesticides.

Did you know?
Risk = Toxicity X Exposure

Acute toxicity of a pesticide is indicated on the label using a signal word (Caution, Warning, Danger, or Danger-Poison) that is required by the EPA. Each pesticide undergoes testing to study impacts of oral exposure, inhalation exposure, and dermal exposure, and for skin and eye irritation, and additional testing is done to determine impacts from chronic exposure. Chronic toxicity is dependent on both the pesticide and amount of exposure. Additional toxicological impacts and any chronic toxicity information are listed in Section 11 of each pesticide’s Safety Data Sheet.

Pesticide exposure occurs when a pesticide is ingested, inhaled, or comes into contact with skin or eyes. Exposure can be reduced by using pesticides appropriately and following label directions.

Visit the National Pesticide Information Center for more information on Pesticide Risk

How do you use pesticides appropriately?

Read the label!

Remove children, toys and pets from the area.

Follow label recommendations for reentry into the area.
Follow label recommendations for any livestock exclusions.

Correctly identify the target species.

Make sure the pesticide you are using is labeled for the area you are treating.

Herbicides are approved for use in different areas such as lawn/turf, pastures, natural areas, aquatic, and industrial sites. Lawn herbicides, for example, are safe for sensitive turfgrass species.
Insecticides are approved for a variety of areas such as indoors, standing water, intermittent water, lawn/turf, vegetable gardens, ornamental plants, and different cropping systems.

Wear Personal Protective Equipment (PPE) required by the label.

Most of the herbicides that TCWP carries require, at a minimum, a long-sleeved shirt and long pants, shoes plus socks, chemical resistant gloves, and protective eyewear, but some herbicides, including organics, require additional PPE including goggles, chemical resistant aprons, or ventilators.
Minimum PPE requirements for insecticides vary widely by product and formulation including those readily available for at home use. Always read the label before using an insecticide.

Ensure climatic conditions are appropriate.

Do not apply pesticides at times when they can be transported off the target area. This includes when winds are above 10 mph, during fog events, and immediately before a rain event. Some herbicides have a maximum temperature to prevent volatilizing and damaging other vegetation. Some pesticides require a light wind (like mosquito adulticides applied by ULV sprayers), and some require a rain or snow event within a few days or weeks of application (like preemergent herbicides used for cheatgrass).

Calibrate your equipment.

Before you can calculate how much pesticide to add to a sprayer, you have to know how much volume the sprayer is putting out. Luckily, it’s relatively easy to do so. The University of Wyoming recommends the 1/128th method for calibrating equipment. Contact us if you need additional assistance calibrating your sprayer.
Ultra-low volume (ULV) sprayers require calibration by a specialist. Each spring, TCWP coordinates with a specialist to calibrate our ULV sprayers. If you have a ULV sprayer that needs to be calibrated, please contact us to be put on our annual call list.
1/128th Calibration Method

Ensure you are using the correct amount of pesticide.

Using either too much or too little pesticide for the target species can have lasting ecological impacts. Make sure you are adding the appropriate amount to your sprayer. Pesticide labels include tables of recommended rates by species.
University of Nebraska example of pesticide use calculation.
If you need additional assistance calculating the amount of pesticide needed, contact TCWP using the chat.

Use a surfactant or other adjuvant if needed.

“Surfactant” is short for “surface-active agent”. Sometimes referred to as “stickers and spreaders” because of how they impact spray mixtures, surfactants aid in the penetration of surfaces. Other types of adjuvants include defoamers, pH correcting products, and indicator dyes.
Each pesticide label will indicate what type of surfactant, if any, is needed and how much to use.

Mix according to label instructions.

Different product formulations (granules, liquid, etc.) may have different mixing instructions and some do not need mixing at all. Product specific instructions are included on the pesticide label.
For herbicides, generally, add ⅓ to ½ of the amount of water needed, add the correct amount of herbicide, add a surfactant, top off with the remaining water needed, and mix or agitate. ALWAYS READ LABEL INSTRUCTIONS BEFORE MIXING.

Clean and dispose of PPE appropriately.

Follow label instructions.
Wash clothing separately from general household clothing.

Store and dispose of pesticide appropriately.

Always store pesticides out of reach of children and pets.
Never dispose of a pesticide down the drain.
Store pesticides away from excessive heat and extreme cold.
Follow label instructions for proper disposal.
Schedule a Household Hazardous Waste Collection appointment with Teton County Integrated Solid Waste & Recycling.

Preventing Pesticide Resistance

Pesticide resistance occurs when a population of a pest (insect, weed, etc.) that was once susceptible or controlled by a specific pesticide or pesticide mode of action is no longer susceptible to that pesticide or mode of action. To be considered pesticide resistance, this change in susceptibility must be heritable by the pest’s offspring and future generations. Pesticide resistance may be identified in the field, but it is confirmed through laboratory testing.

Variability in genetic makeup is helpful for the survival of a species. In the case of pesticide resistance, naturally occurring genetic mutations may allow a pest to be less susceptible to a pesticide. If that pest survives to reproduce, it may pass on that genetic trait. Repeated applications of the same pesticide will not control offspring with that genetic trait allowing that biotype to be widespread.