Using Pesticides Safely

By Mongi Zekri

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. A minimum score of 70% is required to receive credit.

Pesticides should not be considered the first line of defense against pests. Use cultural, mechanical or biological controls first, before using pesticides.

INTEGRATED PEST MANAGEMENT

Integrated pest management (IPM) incorporates cultural, mechanical, biological and chemical control methods in a common-sense approach to pest management. IPM emphasizes establishing and maintaining healthy plants. Healthy, unstressed plants are better able to resist insects and diseases and compete with weeds.

Follow these steps for IPM:

• Learn about plants and their pests.
• Inspect plants regularly.
• Identify damage and the pest.
• Determine if control measures are needed.
• Evaluate your control measures to determine what worked best and what did not.

Pesticides should be considered as one of a few options for managing a pest outbreak. Often, nonchemical control methods work just as well or better to prevent or manage a pest outbreak. Many pesticides target only certain types of pests. Thus, accurate identification of the problem is the critical first step in the process of selecting one or more appropriate control strategies.

THE LABEL

When the use of a pesticide is appropriate, there is one simple rule that must be followed: The label is the law. It is against the law to use a pesticide in a manner not dictated by its label. Therefore, careful reading of the label is the first important step in pesticide usage.

Check product labels to see if your pest and crop are listed. Never assume that a product will control a pest that is not listed on its label. If the label does not name the pest you wish to control, the risk of a control failure falls upon you and not the manufacturer of the product.

In many instances, you may have more than one product choice to control your problem. If so, do not choose on the basis of cost alone. Consider products that may be more friendly to the environment, softer on beneficial organisms and perhaps easier and safer to use.

PESTICIDE TOXICITY

All pesticides are poisonous, some more so than others. Their relative toxicity, and hence the danger they pose to warm-blooded animals, is expressed in a measure known as LD50, which stands for lethal dose, 50%. The LD50 is the amount of a pesticide that resulted in the death of 50% of a test animal population. It is based on milligrams of active ingredient per kilogram of body weight. Thus, the less the LD50, the more toxic a pesticide is to people.

A pesticide label contains one of three signal words to indicate the product’s relative toxicity to humans:

• Danger applies to those pesticides with an LD50 of less than 50. These are highly toxic pesticides that require special certification to buy and use.
• Warning refers to pesticides that are only moderately toxic. The LD50 range for these pesticides is between 50 and 500.
• Caution is applied to pesticides with low to very low human toxicity. The LD50 for this group is more than 500. Most of the pesticides available to the homeowner contain the caution signal word on their labels.

Regardless of the signal word on a pesticide label, remember that every pesticide is toxic and has the potential to poison. Therefore, always read and follow all the directions on the label each time you use a pesticide.

NATURAL PEST CONTROL

Numerous organisms feed upon or infest insect pests. Natural enemies including predators, parasites and pathogens combat insect pests. Microbial insecticides containing the soilborne bacterium Bacillus thuringiensis are popular for the control of a variety of insects.

GENERAL GUIDELINES FOR PESTICIDE USE

Once you have correctly identified the pest causing unacceptable damage, and other control measures have proven impractical or have failed, the careful selection of a pesticide may be a viable alternative. Follow these guidelines for using pesticides:

• Read the label carefully. It tells you when, where and how to use a product.
• Apply only the amount specified on the label and apply only to plants and areas listed on it. Overapplication wastes money and increases environmental hazards.
• Wear protective clothing listed on the label. Do not wash clothing contaminated with pesticides with other clothing.
• Make sure the pest you wish to control is listed on the label. Do not mix different pesticides unless instructed by the product’s label directions.
• Keep pesticides out of the reach of children and pets, and in their original containers with labels attached.
• Check the weather prior to application. Some pesticides are not effective if washed off foliage, while others may need to be watered into the soil for best results. Never spray pesticides on windy days. Spray drift poses serious health risks for nontarget plants and animals.

Many pesticides are available in more concentrated formulations and sold under different brand names for agricultural and industrial uses. Generally, most of these concentrated products are not approved for use by unlicensed people. They are only available to licensed pest control professionals because of toxicity and environmental concerns.

Use the products in a responsible way. Store all pesticides out of reach of children and in their original containers. Pesticides stored in food or soft drink containers invite accidents that can turn tragic. Such misuse of a pesticide is illegal and can expose you to serious liability problems.

APPLY THE CORRECT AMOUNT

Strive for judicious use, guided by the directions on the label. Pesticides are generally not cheap. Using them at high rates of application represents wasted money, time and energy. Extra products can also pose storage and disposal problems. Excessive use increases the potential for environmental harm, making it more likely that pesticides will run off into surface water or leach into groundwater. Overapplication increases the chances that pesticides will damage desirable plants and beneficial organisms and lead to the buildup of resistance in target pests. Moreover, applying pesticides at excessive rates beyond label directions is illegal.

PREVENT EXPOSURE

Pesticides can enter the body in several ways: ingestion, inhalation or contact with the skin. The minimum personal protective equipment (PPE) that must be used when mixing and applying the product is listed on the label. Note that using more than the minimum required PPE is perfectly fine and legal.

The most important PPE to wear is gloves. Some labels will specify waterproof or chemical-resistant gloves. Keep in mind that waterproof does not necessarily mean chemical resistant. Avoid gloves made of cotton or leather when handling pesticides, as these materials tend to absorb and hold residues in contact with the skin.

Eye protection, such as face shields, protective goggles or safety glasses, may also be necessary when using some products, particularly during the mixing process. Regular eyeglasses for correcting vision do not provide adequate protection against pesticide exposure.

When the pesticide application tasks have been completed, follow proper procedures for discarding pesticide containers and for cleaning reusable protective gear with soapy water. Rinse, dry and store protective gear that can be reused in an appropriate location.

Clothing that has been worn while handling pesticides should be laundered separately and then line dried. If the clothing has been heavily contaminated during pesticide application, it should be discarded.

PREPARE FOR AN EMERGENCY

Even when proper precautions are taken, accidents sometimes happen. What do you do if you or someone else experiences dizziness, headache or nausea that you suspect is related to pesticide exposure? In these situations, do not take any chances; contact a medical professional and be ready to take the pesticide label with you if you need to go to a hospital.

The label contains specific information about remedial treatment that medical professionals can follow. In some cases, recommended treatments should start at the spray location before you can reach medical help. However, if someone has collapsed or is not breathing, first call 911.

PROTECT SENSITIVE ENVIRONMENTAL AREAS

To protect yourself and your neighbors, and to help avoid legal liability, read pesticide labels for any recommended or required limits on usage. Especially avoid applying chemicals when it is windy or when a significant rainfall event is forecast. Such weather conditions set the stage for chemicals to move off-site beyond the target area, a situation that can result in fines or lawsuits.

If pesticides are going to be applied to vegetable or fruit crops, be certain to check the product label for the preharvest interval, that is, the amount of time that should elapse between application of the pesticide and harvesting of the vegetable or fruit.

Maintain accurate records. Commercial pesticide applicators are required by law to keep records.

STORE AND DISPOSE OF PESTICIDES PROPERLY

The best way to avoid the need to store excess pesticides is to buy only the amount needed to do the job. Immediate and complete use of every pesticide product may not always be practical, however. When it is necessary to store a pesticide, be sure to store it in its original container away from food, feed, fertilizers and water. The storage location should be locked and well out of the reach of children and pets.

Long-term storage brings additional concerns, mainly about temperature and moisture requirements. Temperature extremes can cause chemical changes in a product’s ingredients and can render them ineffective. Temperature extremes can also cause some products to undergo physical changes that cause their ingredients to form crystalline or gelatinous masses and their components to separate. Dry products, such as granular formulations, can better tolerate temperature extremes but can be ruined by moisture. These formulations have a high affinity for moisture, and once they have absorbed any available moisture, they can quickly form a hard, insoluble mass.

There are several options for proper disposal of pesticides. The best one is to use all the pesticide by applying it to an approved site for an approved use. If you don’t have an immediate use for a product, there is a chance that someone you know may be able to use it. Another option is to store the product only until it can be taken to a hazardous waste collection site for disposal.

Do not pour or flush pesticides down drains, toilets or sewers, and do not leave them on the ground. Do not put unused pesticides in the trash. Pesticide containers must be disposed of in an approved way. Most states prohibit burning any pesticide container.

Under no circumstances should you reuse a pesticide container to carry or store any other substance than the original product. Mixing chemicals, sometimes even in small amounts, can cause unexpected reactions or increased toxicity that could harm humans, pets, wildlife or the surrounding environment. As emphasized throughout this article, read the pesticide label. In addition to the information already mentioned, the label will describe appropriate disposal options for the product and its container.

Once a pesticide container is empty, make sure it is thoroughly cleaned. With liquid formulations, the recommended way to prevent residues is to triple-rinse the container and then to add the water you use for rinsing (called rinsate) directly back into the sprayer as makeup solution. For bags and containers of dry formulations, thoroughly shake these directly onto the site or into the spreader.

For up-to-date information on safe and legal disposal of pesticides and pesticide containers, check the website of your agriculture department or natural resource agency. Alternatively, find the nearest hazardous waste collection facility and deliver it as required by their guidelines, or keep the product securely stored until the next hazardous waste collection event in your area.

Acknowledgments: Original authors include David Trinklein, Extension state specialist, Division of Plants Sciences and Technology, University of Missouri (MU); Mary Kroening, horticulture specialist, MU; and Fred Fishel, professor (retired), University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Department of Agronomy and former director of the UF/IFAS Pesticide Information Office.

Mongi Zekri is a UF/IFAS multi-county citrus Extension agent in LaBelle.

To request a hard copy of the article and test, or if you have questions regarding this article, test or CEUs, contact the author at maz@ufl.edu or 863-674-4092. Please allow two weeks to process your CEU request.