Not all insects in your garden are harmful. In fact, many are beneficial insects which pollinate flowers and/or reduce insect pests. Before you instinctively reach for and apply an insecticide, that may kill the beneficial insects in your garden as well as the pests, determine if there are any non-chemical methods you may use to solve the problem. Integrated Pest Management (IPM) is an approach to dealing with garden pests that does not rely exclusively on chemicals.
A pesticide is any chemical substance that is designed to kill or control a pest. Many people think only of insecticides or herbicides when considering pesticides, but there are a whole range of pesticides, each one designed to control a specific type of pest. Here are a few of the many types of pesticides:
|Pesticide Type||Pest Controlled|
|Herbicides||Weeds and other plants|
Surprisingly, some common household chemicals are also technically pesticides, for they are designed to kill or control pests: bug repellants, household disinfectants, and pool chemicals. All pesticides must be registered with the Federal EPA and Washington State before they may be sold or applied.
Advantages/Disadvantages of Pesticides
Pesticides are powerful chemicals which may have a significant impact on the environment, in either a positive or negative way.
Some of the advantages of pesticides are that they are fast-acting, may be the only remedy that works against a specific pest, can control large infestations, easy to obtain and apply, may increase crop production by reducing crop losses, and their use against pests may significantly improve human health.
Some of the disadvantages of pesticides are that they may damage and/or accumulate within the environment, may kill non-target species, they may be dangerous to users/pets/native species, and can drift from their original point of application.
Remember that not all problems call for the use of powerful chemical pesticides. You should consider non-chemical measures first (for example, mechanical exclusion, sanitation, cultural practices, biologic controls, and planting resistant varieties) before turning to the use of pesticides. This is the philosophy behind Integrated Pest Management (IPM). Explore non-chemical pest control methods first, turning to chemical control only when other measures have not worked and some action must be taken.
Common Types of Garden Pesticides
Herbicides are designed to kill weeds and undesirable plants. They are the most common type of pesticide used in the United States.
- Pre-emergent herbicides prevent seed germination, while post-emergent herbicides kill growing plants.
- Contact herbicides affect only the part of the plant it contacts, while systemic herbicides affect the entire plant.
- Selective herbicides kill only a specific type of plant, while non-specific herbicides kill all plants it comes into contact with.
Insecticides are designed to kill insects. They are the second most common type of pesticide used in the United States.
- Systemic insecticides kill insects, which eat any part of the plant, while non-systemic only kill the insects that eat the treated part of the plant.
- Stomach insecticides must be ingested by the insect to kill, while contact insecticides will kill insects on contact, even if it is not consumed.
- Insecticides kill only insects, but not mites, while miticides kill only mites, not insects.
Fungicides are designed to kill fungi.
- Systemic fungicides are absorbed into and protect the entire plant, while contact fungicides must come into direct contact with the fungus to kill it.
- Protectant fungicides are applied to prevent an infection, while eradication fungicides are applied after an infection has taken place.
- Fungicides kill only fungi, but not bacteria, while bactericides kill only bacteria, not fungus.
Pesticide Physical Forms
Pesticides may be supplied or applied in several physical states: solids, liquids, or gases.
- Dusts, granules, cakes, and baits.
- Advantages: Solid pesticides are easy to apply, don’t drift to another area, and allow for selective site placement.
- Disadvantages: The solid forms of pesticides tend to be expensive and may be eaten by pets.
- Prepared liquids or concentrates/powders which are mixed into a liquid (usually water).
- Advantages: Liquid concentrated pesticides tend to be economical and allow one to only mix what is needed.
- Disadvantages: The user must handle the pesticide and equipment while mixing, there is the danger of pesticide drift, and any unused pesticide mix must be disposed of properly.
- Aerosol or thermal “bombs”, candles, and no-pest strips.
- Advantages: These may cover a large area and penetrate into hidden spaces.
- Disadvantages: The gases may drift or be dispersed by the wind.
How Are Pesticides Applied?
The application method for pesticides varies with the type of pesticide, its physical form, and the location in which it is used. Common application methods include:
- Hand-powered applicators (atomizers and pressurized sprayers).
- Hose-end sprayers.
- Bait traps.
- Dusters and foggers.
- Rotary and drop spreaders.
- Hand distribution.
Homeowners may use any application method except introducing pesticides through an irrigation system. This is prohibited so that pesticides may not be accidentally mixed in with potable water. Look to the pesticide label for guidance.
Often surfactants, additives or adjuvants are used to make pesticides more effective. These may help reduce the tendency of water molecules to form drops and not penetrate into materials, help hold wettable powders in suspension so they may be sprayed, or help the pesticide to stick to the target surface. Using additives increases the efficiency of the pesticide, so less of the chemical needs to be used. Their use should be guided by the specific pesticide label.
The Pesticide Label
Every pesticide has a label which provides valuable information on proper handling, the type of pest it will target, where it may be used, detailed directions for use, protective equipment needed, environmental and health concerns, first-aid information, how the pesticide may be stored or disposed of, and other important information.
The label is the law! Federal law requires that you must read and follow all label instructions exactly.
The only deviations from the pesticide label that are allowed are:
- You may apply a pesticide at a lower rate, concentration or amount than that shown on the label.
- Any application method may be used except introducing pesticides through an irrigation system.
- You may mix with other pesticides unless prohibited by the label.
Signal Words are found on the pesticide label, giving a general indication of the pesticide toxicity from a single exposure. The signal words (going from the least dangerous at the top to the most dangerous at the bottom) are:
- CAUTION: The least dangerous category. Products are slightly toxic and may cause slight skin or eye irritation.
- WARNING: Moderately toxic and may cause moderate skin or eye irritation.
- DANGER: Not toxic, but may cause irreversible eye damage or severe skin injury.
- DANGER-POISON: The most dangerous category. Highly toxic and potentially deadly at low doses. The DANGER-POISON signal words have red lettering and are accompanied with a skull and crossbones symbol.
Which Pesticide Should You Use?
It is impossible to provide blanket guidelines for which pesticide should be used in a specific situation. Since there are thousands of registered pesticides on the market, each homeowner’s situation and pest problem is slightly different, and new research is constantly being done to improve pesticide application recommendations.
To obtain pesticide recommendations for your personal situation, you should either contact your local Extension Office or the Master Gardeners, who will have access to the latest pesticide information.
Pesticides are powerful chemicals, which may cause personal injury, environmental damage, or economic loss. To reduce the chance of unintended adverse consequences, the list below provides some tips on pesticide safety:
- Explore non-chemical pest control options prior to turning to chemical control.
- You must identify the pest involved. Applying a fungicide to a bacterial problem, or a miticide to an insect problem, will not solve your pest problem.
- Use the least toxic pesticide that will work and apply it correctly.
- Follow all label instructions exactly!
- Reduce your exposure to chemicals by wearing and using the proper clothing and equipment. Be careful when mixing chemicals!
- Do not use pesticide measuring cups and containers for any other purpose. Buy measuring cups and containers that are only for pesticide use.
- Due to their toxicity and potential environmental danger, some pesticides are restricted for use only by licensed and trained professionals. The homeowner should never use these chemicals!
- Protect desirable plants, insects, soil, and the water table from exposure and contamination. Avoid pesticide drift and runoff.
- Monitor your children and pets so they are not exposed to the pesticide. Secure your pesticides so that children and others will not have access to them.
- Properly clean all equipment when finished applying pesticides. You may want to have separate fertilizer and pesticide applicators to prevent residual contamination.
- Dispose of pesticides and pesticide containers as directed by the label.
WSU Extension has collected several excellent online references to assist you in identifying and correcting garden and general pest problems.
- Hortsense provides the home gardener fact sheets for managing plant problems with IPM, along with information on cultural controls and Washington-registered pesticides. Hortsense also provides access to several WSU Home and Garden Fact Sheets covering pesticide use and safety.
- Pestsense provides the home gardener fact sheets for managing common indoor pest problems with IPM, along with information on cultural controls and Washington-registered pesticides.
- Urban IPM. The WSU Urban IPM and Pesticide Safety Education Program. Provides education with an emphasis on personal safety, environmental protection, and effective integrated pest management.
- Pesticide Information Center On-Line Washington State University’s Pesticide Label and Tolerance Databases.
- Pesticides Learning About Labels FSIPM001E. WSU publication FSIPM001.
- Pesticides: Safe Handling. WSU publication FSIPM002E.
- Pesticides and Fertilizers. Washington State Department of Agriculture. Extensive information on pesticides used in Washington State and their regulation.
- Washington Poison Center. Provides statewide, 24 hour telephone information to the public and health care providers regarding poisonings and suspected poisonings. New National toll-free telephone number: 1-800-222-1222. Also has information on poisoning prevention.
- National Pesticide Information Center. NPIC is a cooperative effort of Oregon State University and the U.S. EPA. Provides extensive information on pesticides.
- EPA Pesticide Program. United States Environmental Protection Agency. Information on pesticides and their uses/dangers.
- Pesticide Active Ingredient Information. Cornell University. These pesticide profiles include the Extoxnet Pesticide Information Profiles as well as information taken from other sources, such as the EPA and the Federal Register. Pesticides are organized by type of pesticide and active ingredient.