You have a pest problem in your garden – maybe it is hungry insects feeding on your vegetables, or stubborn weeds taking over your flower patch, or fungal diseases killing your lawn. You might consider using pesticides (which include insecticides, herbicides, and fungicides), especially if the problem seems widespread or severe. How do you choose the right pesticides and apply them correctly to support a healthy and thriving garden? How do you ensure your food plants remain safe for consumption and adverse impacts on beneficial species and soil health remain minimal?
Choosing the right pesticide
Home gardeners can generally choose between two types of pesticides: general use pesticides and minimum risk pesticides. Both pesticide types come with labels that explain how to safely handle, use, and dispose of the products. The labels of general use pesticides are reviewed by the Environmental Protection Agency (EPA) and will have an EPA registration number (highlighted by the blue rectangle on Figure 1), typically on the back panel. The labels of minimum risk pesticides are less extensive and are not reviewed by the EPA as they pose minimal risks to humans and the environment. Since these labels lack an EPA registration number, you can verify the product’s authenticity by contacting the Maryland Department of Agriculture’s State Chemist Section (410-841-2721). Alternatively, you can check out this list of approved minimum risk pesticide substances (PDF).
Regardless of the pesticide type, it is important to select a pesticide that has a narrow activity range. If your pest is an insect, you would ideally want a pesticide that targets insects. It would be even better if you could narrow down your insect pest – is it a caterpillar, beetle, or aphid? Some pesticides are more effective against certain pest insects (for example, see the product in Figure 2) and are therefore less likely to harm non-target insects. If you are unable to identify your pest, you can submit questions and photos to the University of Maryland’s Ask Extension service. Ask Extension will help identify the pest and recommend a course of action.
Another important criterion for pesticide selection is human safety, which can be determined from the signal words on the front panel of the label (see the purple rectangle highlighted in Figure 2). Danger signifies high toxicity, warning signifies moderate toxicity, and caution signifies low toxicity. A pesticide that is virtually non-toxic may have no signal word. Ease of use and application frequency can also help make your choice, as it may not always be feasible to measure and mix or frequently apply the product. This information is typically part of the section on directions for use, often found by peeling open the entire label (see the black rectangle highlighted in Figure 1).
What else to look for on the pesticide label
Labels also include the following information on the front panel (see Figure 2): product brand name, ingredients, and the statement “Keep out of reach of children”. Other information found typically on the back panel (see Figure 1, which includes the label peel) are precautionary and other hazard statements, first aid, and storage and disposal sections. It is important to read all these sections properly, including the entirety of the directions for use, prior to the use of the pesticide.
- The precautionary statement typically includes personal protective equipment that needs to be worn during pesticide applications (for example, full-length clothes, gloves, and eye protection) and informs the period of time during which one must not enter or come into contact with the treated area. The signal words are repeated in this section.
- Hazard statements warn of potential hazards to the environment, including soil, water, air, wildlife, and nontarget plants. An example warning statement is “This product is highly toxic to bees”. This section may also include possible fire, chemical, or explosion hazards posed by the product.
- First aid section recommends steps to be taken in case of accidental exposure or poisoning. The instructions vary in accordance with the route of pesticide exposure (swallowing, inhaling, contact, and eye), and include statements like “sip a glass of water if able to swallow”, and “take off contaminated clothing and rinse skin with water for 15-20 minutes”. Often, there is information on who to contact in case of a medical emergency. If you need to visit an emergency health provider, remember to take the pesticide label with you.
- Storage and disposal section provides information on how to store the product (for example, “store in the original container in a cool and dry place” and “protect from freezing”) and dispose of it (for example, “triple rinse the empty container” or “place the empty container in the trash”). The Maryland Department of Agriculture has often had an annual program where one could recycle an empty pesticide container for free. If you would like to dispose of unused pesticides, follow the instructions in the disposal section. Never dispose of pesticides down any indoor or outdoor drain. Many Maryland counties offer options to safely recycle or dispose of household hazardous waste, including lawn and garden pesticides. Current or retired farmers and producers can also avail of a free pesticide disposal program offered by the Maryland Department of Agriculture.
- Directions of use section instructs how to properly use the product. This section typically includes a description of intended uses, mixing and application methods, use rates, and sites where the product may be used. It can also include application restrictions – this consists of statements like “do not apply if rain is predicted within the next 48 hours” or “do not apply when bees are actively foraging”. In many labels, application restrictions are also found within the hazard statements section.
Why is it important to follow the label?
A pesticide is any substance that prevents, destroys, repels, or mitigates pests. Thus, by nature, pesticides negatively impact living organisms. Federal law states that the EPA must ensure that pesticides entering the marketplace do not cause “unreasonable adverse effects to humans or the environment”. To carry out this mandate, the EPA assesses a variety of factors, including data on the pesticide’s chemistry, human health effects, environmental effects, etc. These data help inform the label language ̶ if the label is appropriately followed, the pesticide product should not cause unreasonable adverse effects to humans or the environment. For example, if a pesticide is highly toxic to fish, the hazard statement of the label would include a sentence like “Do not allow pesticide to enter or run off into storm drains, drainage ditches, gutters, or surface waters”. Applicators can be protected from unreasonable adverse effects by complying with precautionary statements like “Avoid contact with eyes” and “Wear chemical-resistant gloves”. Pesticide use/application rates are set to prevent hazardous quantities from entering the environment, including the infested plants you would like to consume.
Given the label’s critical role in minimizing a pesticide’s negative impacts, it is little wonder that the label is the law. Remember, if you use pesticides improperly, you are legally responsible for any consequences that may occur!
U.S. Environmental Protection Agency. Label Review Manual. https://www.epa.gov/pesticide-registration/label-review-manual
American Association of Pesticide Control Officials. FIFRA Minimum Risk Pesticides – 25(b) Product Label Guidance. https://aapco.files.wordpress.com/2018/03/fifra-minimum-risk-pesticides-label-guidance-3-12.pdf
By Niranjana Krishnan, Assistant Professor, Department of Entomology, and Maryland Pesticide Safety Education Program Coordinator