Pesticides: Basic Information

The purpose of this information is to advise property owners on how to safely and effectively use herbicides and pesticides to control pests near waterbodies as part of a sustainable weed management plan for their properties. Bodies of water are particular sensitive to herbicide and pesticide pollution, so the decision to apply them in the vicinity must be taken with great care. Landholders should always consider non-chemical solutions as a preferred option before deciding to use herbicides and pesticides. Herbicides are designed to control pest plants and are useful in many situations for effective eradication. It is important to realize, however, that many herbicides and pesticides are toxic in aquatic ecosystems. Plants, invertebrates, amphibians and fish may be harmed when the herbicide or pesticide moves into the body of water. Remember that herbicides can enter bodies of water either directly through spray or spray drift, or they can move into water via surface water runoff or leaching and sub surface draining.

Integrated Pest Management

IPM is a combination of common sense and scientific principles. It’s a way of thinking about pest management that values:

  • Using knowledge about the pest’s habits, life cycle, needs and dislikes
  • Using the least toxic methods first, up to and including pesticides
  • Monitoring the pest’s activity and adjusting methods over time
  • Tolerating harmless pests
  • Setting a threshold to decide when it’s time to act

These actions are important parts of any IPM endeavor:

  • Identify the pest in the most specific terms possible
  • Learn about the pest’s biology (habits, life cycle, needs and dislikes)
  • Take steps to exclude the pest from the area, if possible
  • Try to remove the pest’s food, water and shelter
  • Determine the pest’s travel patterns and find their home-base
  • Identify all of your control options (the “tools in the toolbox”) before acting

Always read the warning label and safety data sheet before applying or using any pesticide.

What are Pesticides?
Pesticide is a broad name for several different types of substances that are designed to eliminate some type of pest. The term pesticides includes the list below:

  • Herbicides – Products designed to eliminate weeds, brush, foliage
  • Disinfectants are applied to the surface of non-living objects to destroy microorganisms that are living on the objects
  • Fungicides – used to kill parasitic fungi or their spores
  • Insecticides – used to kill insects
  • Natural and Biological Pesticides made of living things, come from living things, or they are found in nature.-
  • Repellents – deters insects or other pests from approaching or settling
  • Rodenticides – designed to kill rodents

Pesticide Information
Consumer grade pesticides that are sold at retail stores are designed to be used by home and property owners to eliminate some type of pests. These products may be premixed by manufacturer for easy application or are mixed with water by the property owner.
Commercial grade pesticides are sold to licensed and trained applicators. These should never be used by consumers without a current applicator license.
EPA requires that all pesticides containers labels includes a signal word to warn consumers of possible health effects if an exposure occurs.

Signal Words
Signal words are found on pesticide product labels, and they describe the acute (short-term) toxicity of the formulated pesticide product. The signal word can be either: DANGER, WARNING or CAUTION. Products with the DANGER signal word are the most toxic. Products with the signal word CAUTION are lower in toxicity.1 The U.S. Environmental Protection Agency (EPA) requires a signal word on most pesticide product labels. They also require it to be printed on the front panel, in all capital letters, to make it easy for users to find.
The only pesticide products that are not required to display a signal word are those that fall into the lowest toxicity category by all routes of exposure (oral, dermal, inhalation, and other effects like eye and skin irritation).
CAUTION means the pesticide product is slightly toxic if eaten, absorbed through the skin, inhaled, or it causes slight eye or skin irritation.
WARNING indicates the pesticide product is moderately toxic if eaten, absorbed through the skin, inhaled, or it causes moderate eye or skin irritation.
DANGER means that the pesticide product is highly toxic by at least one route of exposure. It may be corrosive, causing irreversible damage to the skin or eyes. Alternatively, it may be highly toxic if eaten, absorbed through the skin, or inhaled. If this is the case, then the word “POISON” must also be included in red letters on the front panel of the product label.

Pesticide products include both active ingredients and inert (other) ingredients. Active ingredients are used to kill, control or repel the pest. Other ingredients may do a variety of jobs, like attracting the pest, spreading the active ingredients around, and/or reducing drift.

Active Ingredients
Active ingredients are the chemicals in a pesticide product that act to control the pests. Active ingredients must be identified by name on the pesticide product’s label together with its percentage by weight. There are several categories of active ingredients:

  • Conventional – are all ingredients other than biological pesticides and antimicrobial pesticides
  • Antimicrob – are substances or mixtures of substances used to destroy or suppress the growth of harmful microorganisms whether bacteria, viruses, or fungi on inanimate objects and surfaces
  • Biopesticides – are types of ingredients derived from certain natural materials

Inert Ingredients
Pesticide products contain at least one active ingredient and other intentionally added inert ingredients. Called “inert ingredients” by the federal law, they are combined with active ingredients to make a pesticide product. Inerts are chemicals, compounds, and other substances, including common food commodities (e.g., certain edible oils, spices, herbs) and some natural materials (e.g., beeswax, cellulose).

The name “inert” does not mean non-toxic. All inert ingredients must be approved by EPA before they can be included in a pesticide. We review safety information about each inert ingredient before approval. If the pesticide will be applied to food or animal feed, a food tolerance is required for each inert ingredient in the product, and we may limit the amount of each inert ingredient in the product.
Inert ingredients play key roles in pesticide effectiveness and product performance.

Examples of functions inert ingredients serve include:

  • Act as a solvent to help the active ingredient penetrate a plant’s leaf surface.
  • Improve the ease of application by preventing caking or foaming
  • Extend the product’s shelf-life.
  • Improve safety for the applicator.
  • Protect the pesticide from degradation due to exposure to sunlight.

Under federal law, the identity of inert ingredients is confidential business information. The law does not require manufacturers to identify inert ingredients by name or percentage on product labels.
In general, only the total percentage of all inert ingredients is required to be on the pesticide product label.

Pesticide Application

Spray Drift
What is spray drift: Spray drift is the airborne movement of chemicals away from the target area, during or shortly after its application. Spray drift can be in the form of droplets, particles (dusts) and vapor, and becomes an issue when it has the potential to impact human health, trade and the environment. When using pesticides around water please keep these tips in mind:

  • Always read and follow the label directions: some pesticides are specially formulated for use in and around waterways.
  • Pesticide use directions may vary between marine and fresh water environments. Buffer zones may be required.
  • Permits or licenses may be required for any chemical application to water. Check with your state pesticide regulatory office.
  • Avoid small droplet sizes when spraying. They are more likely to drift or volatilize.
  • Always clean pesticide application equipment in a location where rinse water cannot enter storm drains or waterways.
  • Consider an Integrated Pest Management (IPM) approach that is designed to have less impact on the environment.
  • Consider the weather conditions during the pesticide application and up to 48 hours afterward.
  • Rain can wash the pesticide off the application site into drains or waterways.
  • Fog and humidity can prolong drying times and increase potential for runoff.
  • High temperatures can increase the likelihood of volatilization of the pesticide, which can then be moved through the air and deposited off-site.
  • Excessive wind can lead to the pesticide drifting off site.
  • Floods and other natural disasters can move pesticides into waterways.

Pesticide References:
Safe and effective Herbicide use; a handbook for near-water applications,
National Pesticide Information Center —