10 Pesticide Management
Pesticide use should be part of an overall IPM strategy that includes biological controls, cultural methods, pest monitoring, and other applicable practices, as discussed in the “Integrated Pest Management” chapter of this document. When a pesticide application is deemed necessary, product selection should be based on effectiveness, toxicity to humans and non-target species, cost, site characteristics, and persistence and other factors that may impact the environment.
Storage and handling of pesticides in their concentrated form poses the highest potential risk to groundwater or surface water. For this reason, it is essential that, in addition to compliance with state and federal laws, careful consideration be given to site selection, design, construction and operation of facilities and areas used for storing and handling pesticides be properly, designed, constructed, and operated in accordance with federal and Delaware regulations.
10.1 Regulatory Considerations
Pesticides contain active ingredients, which target the pest, and inert ingredients, such as solvents, surfactants, and carriers. Both active and inert ingredients are regulated by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), as well as by state and local laws, due to environmental and health concerns. The DDA Pesticide Regulation Section is designated as the lead agency for enforcement of the Delaware Pesticide Law. As such, DDA is responsible for:
- Regulating the use, sale, storage, and disposal of pesticides.
- Certifying pesticide applicators.
- Ensuring that pesticides are applied by competent individuals.
- Establishing guidelines for the application of pesticides.
In addition to federal registration as required under FIFRA, all pesticide products distributed, sold, or transported in Delaware must be registered with the Pesticides Section of the DDA. The Delaware Pesticide Registration and Labeling Law requires a distributor of a pesticide product to register every pesticide product each year with the DDA before that product can be sold or distributed in the state. The DDA maintains a database of pesticides registered in the state which can be searched on line.
In Delaware, pesticide storage areas must meet federal minimum requirements set by United States Environmental Protection Agency:
- The storage area must be secured or locked to prevent unauthorized access.
- Pesticides must be stored in a separate building or, at a minimum, must be separated by a physical barrier from living and working areas and from food, feed, fertilizer, seed, and safety equipment.
- A warning sign approved by DDA must be placed on the exterior of the storage area.
- Pesticides must be stored in a dry, ventilated area.
- The pesticide storage area must be kept clean.
- A supply of absorbent material sufficient enough to absorb a spill equivalent to the capacity of the largest container in storage must be kept in the storage area.
- The storage area must contain only pesticide containers that are properly labeled and are free of leaks.
- The storage area must have an appropriate fire extinguisher available.
- Pesticides must be stored in an area located at least 50 feet from any water well or stored in secondary containment approved by DDA.
The use of aquatic pesticides is subject to a recent court decision, which mandated that USEPA and all state environmental agencies permit pesticide applications in/near water. In Delaware, this requirement is regulated under the National Pollutant Discharge Elimination System (NPDES) program administered through DNREC. As a result, DNREC’s Secretary signed a Secretary’s Order to adopt emergency regulations, Regulations Governing the Discharges from the Application of Pesticides to Waters of the State. For more information, see the FAQ published by DNREC and the Aquatic Pesticides Section of DNREC.
10.2 Human Health Risks
Pesticide chemical classifications that vary greatly in their toxicity to human health, non-target organisms, and the environment. This is true with pesticides that are considered conventional and organic. The human health risk associated with any pesticide use is related to both pesticide toxicity and level of exposure. Immediate attention, and specific care and treatment depends on the type of pesticide and the route of exposure. The pesticide label provides information on personal protective equipment (PPE) required to minimize exposure, and first aid information specific to the product. Therefore, applicators should always read and follow the label before using a pesticide in addition to following standard safe practices.
Safety Data Sheets (SDS) (formerly Material Safety Data Sheets [MSDS]) also provide important information on hazardous chemicals. Using SDS in conjunction with the product label will provide not only a good description of the potential risks, but also appropriate and required exposure minimization measures that will help reduce any such risks.
For more information, see the following publications:
- Pesticide Information Leaflet No. 11: Practices for Safe Use. 2013. University of Maryland Extension.
- Pesticide Information Leaflet No. 28: How to Read a Pesticide Label. 2013. University of Maryland Extension.
- Pesticide Information Leaflet No. 29: How to Read a Material Safety Data Sheet (MSDS). 2013. University of Maryland Extension.
- Pesticide Information Leaflet No. 46: First Aid for Pesticide Emergencies. 2013. University of Maryland Extension.
10.3 Personal Protective Equipment
Exposure to pesticides can be mitigated by practicing good work habits and using pesticide mix/load equipment (e.g., closed loading) that reduce potential exposure. PPE, such as specific types of clothing, goggles, respirators, etc., protects workers from one or more of the following routes of exposure: skin, eyes, oral ingestion, or respiratory tract (Figure 22).
Pesticide labels list legal requirements for specific required. However, as a habit, minimum PPE should be gloves, long sleeve shirt and pants (or similar coverall), socks, and shoes. SDS also provide information on appropriate PPE to wear while handling the product as formulated. To avoid contamination, PPE should not be stored in a pesticide storage area. For more information, see the Personal Protective Equipment information on the Pesticide Environmental Stewardship website.
10.4 Environmental Fate and Transport
Potential environmental impact of a pesticide can often be determined by the environmental hazards statement found on product label. The environmental hazards statement (referred to as “Environmental Hazards” on the label and found under the general heading “Precautionary Statements”) provides the precautionary language advising the user of product specific concerns. Potential environmental impacts include contamination of surface water or groundwater and toxicity to non-target organisms, especially aquatic species.
The key to preventing pesticide impacts on the environment is an understanding of the physical and chemical characteristics that determine a pesticide’s interaction with the environment: solubility, adsorption, persistence, and volatilization. These characteristics influence the potential for pesticide runoff, leaching, or drift. Once applied, pesticides can move off-site in several ways: in water, in air, attached to soil particles, and on or in objects, plants, or animals.
To prevent the off-site movement of pesticides, site-specific characteristics and prevailing conditions should be evaluated, and taken into consideration to ensure selection of the appropriate pesticide. Site-specific characteristics, such as soil type, leaching potential of the chemical, depth to the water table, geology, and proximity to surface water should all be considered before selecting and applying pesticides. For example, highly permeable materials such as gravel deposits or the sandy soils characteristic of much of Delaware allow water and dissolved compounds to freely percolate down to groundwater.
In addition to site characteristics, prevailing weather conditions, such as chance of precipitation, prevailing wind, temperature humidity, etc., should be evaluated with respect to the timing of pesticide applications. For example, if rainfall is high and soils are permeable, water that carries dissolved pesticides may take only a few days to percolate downward to the groundwater.
10.4.1 Leaching and Runoff
Most pesticide movement in water is either by surface movement off the treated site (runoff) or by downward movement through the soil (leaching). Runoff and leaching may occur when:
- Too much pesticide is applied or spilled onto a surface.
- Too much rainwater or irrigation water moves pesticide through the soil off-site or into groundwater.
- Highly water-soluble or persistent pesticides are used.
- Soil structure.
The mobility of a substance in soil is referred to as a Soil Adsorption Coefficient (Kd/Koc). Weakly sorbed pesticides (compounds with small Koc values) are more likely to leach through the soil and reach groundwater. Just the opposite is the case with strongly sorbed pesticides (compounds with large Koc values) which are more likely to remain near the soil surface, reducing the likelihood of leaching but increasing the chances of being carried to surface water via runoff or soil erosion.
Pesticide movement away from the application site by wind or air currents is called drift. Pesticides may be carried off-site in the air as spray droplets, vapors, or solid particles, even on blowing soil particles.
Air drift: Air drift is a function of droplet size. Small, fine drops with diameters of 100 microns or less tend to drift away from targeted areas.
Vapor Drift: Volatile pesticides can change readily from a solid or liquid form into a gas under the right conditions (i.e., high temperatures) and cause vapor drift.
Particle drift: Particle drift is the movement of solid particles from the target area by air during or just after an application. These solid particles may include pesticides formulated as dust or soil particles to which pesticides are attached.
Application techniques, the type of equipment used, and nozzle size, greatly influence the amount of drift that may occur. Nozzle selection and coverage, in particular, is important in the control of drift. The type of nozzle, nozzle orifice size, sprayer pressure, and the height or distance of the nozzles from the target affect the potential for off-site movement of pesticides. A nozzle that primarily produces coarse droplets is usually selected to minimize off-target drift. The pesticide label should be reviewed for specific information on drift reduction techniques or requirements.
Environmental fate- and transport-related topics are covered in greater detail in the following publications:
- Chapter 7 “Pesticides in the Environment” of the Maryland Pesticide Applicator Core Manual.
- Pesticide Information Leaflet No. 8: Factors Affecting Groundwater Contamination. 2012. University of Maryland Extension.
- Pesticide Information Leaflet No. 9: Protecting Groundwater from Pesticides. 2012. University of Maryland Extension.
10.5 Application Equipment and Calibration
Application equipment must ensure that the pesticide reaches the intended target at the proper rate. Information on the label specifies the legal application rate and sometimes suggests the appropriate equipment for use with the product. While different kinds of application equipment are available, nearly 90% of all pesticides are formulated for spraying. The size of the equipment (tank size, boom width, etc.) should be matched to the scale of the facility and areas of application.
To apply pesticides at the proper rate, properly calibrated application equipment is essential. These practices help mitigate environmental and human health concerns, reduce the chances of over- or under-applying pesticides and optimize pesticide efficacy. Equipment should also be checked frequently for leaks and malfunctions and repaired promptly.
For more information on pesticide application equipment and calibration, see Chapter 11 “Pesticide Application Procedures” in the Maryland Pesticide Applicator Core Manual.
10.6 Pesticide Record Keeping
Maintaining accurate records of pesticide-related activities (for example, purchasing, storage, inventory, applications, etc.) is essential to an effective pest management program. Delaware pesticide regulations require records of Restricted Use Pesticides applications must be kept and retained for two years. The following information must be documented:
- name of applicator and certification #
- date and time of application
- location of application
- area treated and number of acres
- pest and type of plant
- product name, active ingredient, and EPA registration number of pesticides used
- rate of concentration of pesticide used
- total amount of pesticide used
- restricted entry interval, re-entry date/time
- posting requirements and information
- wind direction/speed
- frelative humidity
DDA provides a pesticide application recommended form that provides compliance guidance for the keeping of pesticide application records in accordance with state and federal regulations.
10.7 Pesticide Transportation, Storage, and Handling
Storage and handling of pesticides in their concentrated form poses the highest potential risk to groundwater or surface waters. For this reason, it is essential that facilities for storing and handling these products be properly sited, designed, constructed, and operated. In addition, storing large quantities of pesticides for long periods of time should be avoided. Adopting a “first in-first out” management system for pesticide purchase and storage helps to avoid a buildup of large quantities of chemicals.
At a minimum, Delaware regulations require that pesticide storage areas must meet requirements as described previously under Regulatory Considerations section of this chapter. For more information on pesticide storage recommendations, see the following:
- Pesticide Storage Facilities. 2004. Rutgers University.
- Store Pesticides Safely. 2016. Clemson University.
- Pesticide Storage, Pesticide Environmental Stewardship website.
- Pesticide Information Leaflet No. 39: Pesticide Storage and Security. 2012. University of Maryland.
10.8 Mixing/Washing Station
Proper cleaning of equipment helps prevent residues from reaching surface waters, groundwater, drainage pipes, or storm sewers. The residues from washing equipment include grass clippings, soil, soaps, oil, fertilizers, and pesticides. Therefore, equipment washing should be conducted under controlled conditions in an appropriate contained area with minimal risk to the environment and to prevent adverse washwater and stormwater runoff impacts. Equipment washing guidelines and restrictions should be established that reduce the potential for pollutants to reach stormwater runoff, surface water or groundwater.
For equipment with pesticide residues, BMPs should be followed to ensure that washwater does not become pollution source. Captured washwater can be used as a dilute pesticide per label, or it may be pumped into a rinsate storage tank for use in the next application and used as a dilute pesticide per the label.
For more information on pesticide equipment cleaning, see the following publications:
- Cleaning Your Sprayer. 2012. Cornell University.
- Maintenance, Cleaning and Storage of Ground Sprayers. 2017. Montana State University.
- Sprayer Clean-Out Guidelines. 2012. University of Delaware Cooperative Extension.
- Cleaning Pesticide Application Equipment. 2018. University of Nebraska Extension.
There is usually no safe and legal way to dispose of leftover pesticide from professional applications and therefore all of the chemical must be used according to directions on the label. This includes wash water from pesticide equipment washing, which must be used in accordance with the label instructions.
Often pesticide storage facilities accumulate unusable or unwanted pesticide products. They can accumulate for a variety of reasons, e.g. mistakes made in calculating the amount of product needed or the launch of new product chemistries that may be more effective at controlling target pests. Disposing of these stockpiles properly may be challenging. Simply keeping them in storage eventually becomes problematic when packaging inevitably deteriorates or corrodes and creates a hazard. The DDA’s Environmental Sweep Program offers environmentally responsible disposal of unwanted, outdated or cancelled pesticides to qualifying individuals and businesses, including golf courses. This program offers free removal of up to 500 pounds or 50 gallons of pesticides, picked up by a waste disposal contractor.
10.10 Pesticide Container Management
Handling of empty pesticide containers must be done in accordance with label directions as well as with all federal, state, and local laws and regulations. Under the federal Resource Conservation and Recovery Act, a pesticide container is not empty until it has been properly rinsed. However, pesticide containers that have been properly rinsed can be handled and disposed of as non-hazardous solid waste. Federal law (FIFRA) and state law requires pesticide applicators to rinse all empty pesticide containers before taking other container disposal steps. For more information on proper pesticide container disposal procedures, see Pesticide Information Leaflet No. 13: Disposal of Pesticide Containers. 2012. University of Maryland.
After following proper procedures (such as pressure rinsing, triple rinsing, puncturing, etc.), pesticide containers be either recycled through an approved program or disposed of by depositing them in a licensed sanitary landfill. DDA’s Pesticide Section, in cooperation with the Ag Container Recycling Council (ACRC), provides an empty pesticide container recycling program in the State of Delaware. For more information, see the DDA’s Pesticide Calendar of Events web page.
10.11 Pesticide Management Best Management Practices
Human Health Risks Best Management Practices
- Select the least toxic pesticide with the lowest exposure potential.
- Read the pesticide label before mixing or applying a pesticide.
- Use appropriate PPE as per the pesticide label.
- Follow standard safe practices for the use of pesticides.
- In case of exposure, refer to the pesticide label and SDS for more information.
PPE Best Management Practices
- Provide adequate PPE for all employees who work with pesticides (including equipment technicians who service pesticide application equipment).
- Ensure that PPE is sized appropriately for each person using it.
- Make certain that PPE meets the minimum requirements listed on the pesticide label.
- Ensure that PPE meets rigorous testing standards and is not just the least expensive.
- Store PPE where it is easily accessible, but not in the pesticide storage area.
- Forbid employees who apply pesticides from wearing facility uniforms home.
- Wear gloves with sleeves out over the top of the glove to avoid the potential for pesticides to get inside the glove and expose skin. For overhead applications, gloves should be worn over the top of the sleeves and cuffed to catch any potential pesticide residue
- Meet requirements for the Occupational Safety and Health Administration (OSHA) 1910.134 Respiratory Protection Program. The major purpose of this federal law requires medical evaluation and fit testing of workers who are applying pesticides with a label requirement requiring tight-fitting respirators. Employers are required to provide these services for workers.
Environmental Fate and Transport Best Management Practices
- Use drift retardants when needed which will reduce spray drift by hindering formation of small, drift-prone droplets.
- Consider pesticide sorption principles in selecting pesticides.
- Understand site characteristics that are prone to leaching losses (e.g., sand-based putting greens, coarse-textured soils, and shallow water tables) and select pesticides for these areas that have a low leaching potential.
- Understand site characteristics that are prone to runoff losses (such as steep slopes) and select pesticides for these areas with a reduced runoff potential.
- Select pesticides with reduced impact on pollinators.
- Select pesticides that, when applied according to the label, have no known effect on listed species or species of concern present on the facility.
- Time product applications for favorable prevailing conditions.
- Do not make applications during windy conditions or during temperature inversions.
- Avoid using volatile pesticides. If used, follow precautionary statements on the label and do not apply during high temperatures.
- Apply pesticides at the appropriate rate and prevent unintended releases.
- Exercise caution when using spray adjuvants that may facilitate off-target movement.
- Schedule the timing and amount of irrigation needed to water in products (unless otherwise indicated on label) without over-irrigating.
- Select spray nozzle sizes and types that produce droplets that are less likely to drift off target.
Application Equipment Best Management Practices
- Use appropriately sized application equipment for the size of area being treated.
- Ensure the spray technician is experienced, properly trained, and preferably certified as a pesticide applicator.
- Minimize off-target movement by using properly configured application equipment with nozzles selected to ensure coverage while minimizing drift.
- Properly calibrate all application equipment at the beginning of each season (at a minimum) or after equipment modifications.
- Check equipment daily when in use.
- Use recommended spray volumes for the targeted pest to maximize efficacy.
- Calibration of walk-behind applicators or backpack sprayers should be conducted for each person making the application to take into consideration their walking speed, etc.
Pesticide Record Keeping Best Management Practices
- Keep and maintain records of pesticides used in order to meet legal (federal, state, and local) reporting requirements.
- Records should be completed as soon as possible after the application is completed.
- Use records to monitor pest control efforts and to plan future management actions.
- Use electronic or hard-copy forms and software tools to properly track pesticide inventory and use.
- Develop and implement a pesticide drift management plan.
- Keep a backup set of records in a safe but separate storage area.
Pesticide Transport, Storage, and Handling Best Management Practices
- Maintain an up-to-date inventory of all pesticides purchased, including date of purchase and current quantity in inventory, and the SDS for each chemical.
- Avoid purchasing large quantities of pesticides that require storage for greater than six months.
- Adopt the “first in–first out” principle, using the oldest products first to ensure that the product shelf life does not expire.
- Store, mix, and load pesticides away from sites that directly link to surface water or groundwater.
- Store pesticides in a lockable concrete or metal building that is separate from other buildings.
- Clearly identify the building as a pesticide storage area.
- Locate pesticide storage facilities away from other structures to allow fire department access.
- Storage facility floors should be impervious and sealed with a chemical-resistant paint.
- Floors should have a continuous sill to retain spilled materials and no drains, although a sump may be included.
- Sloped ramps should be provided at the entrance to allow the use of wheeled handcarts for moving material in and out of the storage area safely.