CropLife America Drones Working Group Information Hub

Disclaimer

Welcome to CropLife America Drones Working Group (CLA DWG)’s Information Hub for the United States Drone Applicator Community. This hub is NOT intended to replace label language and/or federal, state, tribal, and/or local regulatory guidance, but rather intends to serve as a central source of information that the regulated pesticide community (i.e. CropLife America and RISE) feels is important to be made readily available to drone researchers, applicators, operators, and/or companies utilizing drones to apply pesticides.

Pesticide Application via UASS

Pesticide applications made by Uncrewed Aerial Spray Systems (UASS), or drones, are an emerging practice that current regulatory frameworks should work to fully incorporate. CLA supports the US Environmental Protection Agency (EPA or the Agency)’s position to enable these technologies’ commercial use for products registered for manned aerial application since, in general, the anticipated UASS use pattern is covered by existing risk assessments, knowing that potential further data generation will facilitate their fit into the regulatory risk assessment process.

    • Unmanned Aerial Vehicles (UAVs), also known as drones, are aircraft that operate without a human pilot on board the aircraft. They can be remotely controlled or can fly autonomously based on pre-programmed flight plans or more complex dynamic automation systems which do rely on human intervention from a distance. UAVs have a wide range of applications, including agriculture, real estate, aerial photography, surveying, military and defense, and various commercial and recreational uses.

    • Uncrewed Aerial Spray Systems (UASS) are a specific type of UAV designed for agricultural purposes. These systems are equipped with spraying equipment to apply fertilizers, pesticides, or other agricultural chemicals to crops. UASS can offer benefits over traditional applications in certain scenarios and can overall be seen as complimentary alongside conventional spray technology

    • Other terms for UASS are: Unmanned Aerial Spray System (UASS), Remotely Piloted Aerial Application System (RPAAS), Unmanned Aerial Application Systems (UAAS), spray drones, aerial spraying UAVs, agricultural drones, aerial application drones, crop spraying drones, etc.

    • Other terms for UAV are Unoccupied Aerial Vehicle (UAV), Unmanned Aerial System (UAS), Remotely Piloted Aerial System(s) and Remotely Piloted Aircraft System(s) (RPAS), Remotely Piloted Aircraft (RPA), Remotely Piloted Vehicle (RPV), Unmanned Vehicle System (UVS), etc.

    • At CropLife America, we elect to use the term Uncrewed Aerial Spray Systems (UASS).

  • The potential benefits of drone technology in the U.S. can be categorized into several areas including Flexibility, Cost, Worker Exposure, Innovation, and Environment & Sustainability. While this is an exciting space, it should also be noted that in many geographies, UASS represent a complementary application technique to existing methods, and an additional skill and technique to manage and maintain. Further understanding of their unique value and best local practices will help position their use appropriately and more effectively. These are examples of potential benefits and will depend on the farm operation and use. Comparison of incorporating UASS technology into current practices and evaluating benefits will need to be done on a case-by-case basis.

    • Flexibility:

      • Amenable technology for hard-to-access locations: Drones can easily reach areas that are difficult and unsafe for traditional equipment to access such as muddy fields, areas below power lines, near wind turbines, and irregularly shaped fields

      • A complementary spray solution alongside traditional application technologies such as tractors and conventional aircraft

      • Larger areas can be treated precisely with multiple coordinated drones (called swarms)

    • Cost:

      • Relatively less expensive technology compared to more expensive and larger equipment (e.g., large ground sprayers)

      • Decreased application costs due to optimized and targeted applications and potential reduction of chemicals needed compared to broadcast applications

      • Decreased crop damage due to minimizing ground-based sprayer field tracks

    • Innovation:

      • Enabling the future of digital and precision tools including targeted and optimized applications

      • Positive industry disruption, including attracting a diverse and technology-advanced workforce, creating new business models such as spray-as-a-service, and engaging technology partners not historically associated with agriculture

      • Uses beyond agriculture that support public and environmental health (mosquito applications, dam and railway maintenance, forestry, rights-of-way maintenance, land, invasive species, etc.)

    Environment & Sustainability:

    • Input reduction via customized rates, optimal timing, and targeted placement: Drones can apply inputs such as fertilizers and pesticides more efficiently

    • Emissions reduction: Using drones, which primarily rely on battery power, can lower the carbon footprint compared to traditional machinery if they utilize solar power

    • Reduced water consumption due to lower required water volumes than ground application

    • Soil health improvement due to less soil compaction than with conventional ground equipment

    Smaller scale aerial drone application enables specialty crop care in small acreages, orchards, and vineyards

  • As the field of drone technology grows, coordination among stakeholders is crucial for its effective and efficient implementation. The Organization for Economic Cooperation and Development (OECD) Working Party on Pesticide Drone/UASS Subgroup, of which the EPA is a participant, has reviewed information gaps and recommended steps for incorporating drone technology into regulatory risk assessments. The resulting document, “Report on the State of the Knowledge – Literature Review on Unmanned Aerial Spray Systems in Agriculture,” was released by (Australian Pesticides and Veterinary Medicines Authority) APVMA in 2021 and is available on the OECD website:

    https://one.oecd.org/document/ENV/CBC/MONO(2021)39/En/pdf

    The CLA DWG will contribute perspectives on regulatory considerations for UASS, focusing on the main regulatory gaps highlighted in this OECD report: spray drift (off-site movement), crop residue, operator exposure, and registration/label language. Further information can be found on the status of these regulatory gaps in the 2021 CLA DWG white paper:

  • The application of pesticide products requires expertise and stewardship in the proper use and safe handling of products with specific BMPs, especially with a new technology like UASS. BMPs increase the likelihood of environment and operator protection while considering economic factors, availability, technical feasibility, and effectiveness. As such, risk mitigation measures and regulatory requirements need to be established for UASS as they have been for other pesticide application techniques. This will help to encourage the safe and reliable use of UASS for pesticide applications.

    BMPs are intended to supplement information on the product label and the registered and current product label should ultimately be followed above any other source of information. Readers should therefore ensure that BMP guidance is adapted or supplemented by other country/state/region specific needs, conditions, laws, and regulations, as relevant, including official and required UAV pilot training, to ensure safe operations, which may not be explicitly mentioned on labels. There are on-going initiatives to establish BMPs for UASS and we’ve listed the resources we’re aware of below as of August 2024:

    Unmanned Aerial Pesticide Application System Task Force (UAPASTF) Best Management Practices: https://uapastf.com/wp-content/uploads/2024/09/MASTER-UAPASTF-BMP-final-Sept-2024.pdf

General Pesticide Information

  • Pesticides are important for helping farmers grow more food on less land by protecting crops from pests, diseases, and weeds as well as raising productivity. Without pesticides, more than half of our crops would be lost to pests and diseases. 

    Pesticides are any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest, intended for use as a plant regulator, defoliant, or desiccant, or any nitrogen stabilizer.

    Pesticides are used in agriculture to control weeds, insect infestation, and diseases. Pesticides are also used to control various pests and disease carriers, such as mosquitoes, ticks, rats, and mice. There are many different types of pesticides; each is meant to be effective against specific pests. Some examples include:

    • Algaecides to kill and/or slow the growth of algae

    • Antimicrobials to control germs and microbes such as bacteria and viruses

    • Disinfectants to control germs and microbes such as bacteria and viruses

    • Fungicides to control fungal problems like molds, mildew, and rust

    • Herbicides to kill or inhibit the growth of unwanted plants, also known as weeds

    • Insecticides to control insects

    • Biopesticides, which are types of ingredients derived from certain natural materials

    • Insect Growth Regulators to disrupt the growth and reproduction of insects

    • Rodenticides to kill rodents like mice, rats, and gophers

    • Wood Preservatives to make wood resistant to insects, fungi, and other pests

    More information on pesticides can be found at many websites including:

    Read more

  • READ THE LABEL BEFORE USE.

    Always read and follow label directions before buying or using a pesticide. Follow all appropriate federal, state, tribal and local regulations. The label is enforceable by law and every applicator has the legal responsibility to follow it. NOTE: Even if two products contain the same active ingredient, the label instructions, including safe handling information, could be different.

    A product label defines what crops the product is approved for use on, how the product may be applied, what protective clothing or equipment the applicator must use, including personal protective equipment (PPE), required buffer zones, precautions, potential impact on non-target organisms such as pollinators, along with other limits and restrictions. Additionally, best practices should be followed such as washing work clothing separately from household clothing.

    All pesticide products contain labels that must be approved by EPA. Each label must include:

    • Where the product can and cannot be applied

    • Necessary application equipment and safety instructions

    • Relevant restrictions for use

    • How much of the product to use and when to apply it

    • Where and how to store the product

    • How to rinse and dispose of the empty product container

  • Similar to the process for approving vaccines, and medicines, EPA reviews hundreds of studies conducted for each pesticide by manufacturers and third parties in the U.S. and around the world. These studies provide data and results related to impacts on non-target species and the environment, and risks to human health, just to name a few. Studies assess one-time exposure as well as “prolonged and repeated exposure” in order to determine risks of developing certain diseases over time. Studies must be conducted consistent with international scientific standards, such as Good Laboratory Practices, ensuring that even studies conducted by manufacturers can be relied-upon.

    By law, the EPA may request whatever data they need to ensure the safety of a pesticide product. EPA’s in-house, career scientific staff experts are themselves advised by renowned independent experts, including the National Academy of Sciences, and many have worked over decades under multiple Administrations to help ensure that pesticides are safe for the public and environment when used accordingly. The deliberately long and demanding scientific study requirements are the primary reason only about one in 10,000 discoveries will make the long (more than 12 years) and costly journey from the lab to the farmer’s field.

    The strict and often lengthy regulatory process helps to ensure that pesticide products meet the high safety standards for approval. Even updating label language for an existing and approved pesticide product can take months to years. Once federally approved, a pesticide must then undergo state review and approval which is another process that adds time to the registration process and depends on the state process.

    For more information on pesticide registration, see the EPA website:

    The pesticide industry spends $71 million on safety tests for every pesticide brought to market and it takes more than ~12 years to develop a new product from discovery to commercialization.

  • The EPA classifies pesticides as either general use or restricted use (RUP). General use pesticides can be purchased and used by the general public without a license. RUPs, however, are not available for purchase or use by the general public and any person who applies or supervises the use of RUPs needs to be certified in accordance with EPA regulations and state, territorial, and tribal laws.

    RUPs will state “restricted use” on the product label. Federal law and regulations require any person who applies or supervises the use of RUPs be certified as a private or commercial applicator. If you apply pesticides for the production of an agricultural commodity on land you or your employer owns or rents, you are a private applicator, otherwise you are a commercial applicator.

    More information here:

    https://www.epa.gov/pesticide-worker-safety/how-get-certified-pesticide-applicator

  • Always read and follow label directions before buying or using a pesticide. Follow all appropriate federal, state, tribal and local regulations. The label is enforceable by law and every applicator has the legal responsibility to follow it.

    Safety Precautions

    • Always wear appropriate PPE when handling pesticides and their containers.

    • Avoid contaminating water sources during the rinsing process.

    • Ensure that rinse water is used in a manner consistent with the pesticide label instructions.

    Environmental Considerations

    • Proper disposal of pesticide containers helps prevent soil and water contamination.

    • Recycling helps reduce waste and supports environmental sustainability.

    Managing and disposing of empty pesticide containers must be done with care to avoid environmental contamination and ensure public safety. It’s important to check and comply with specific local regulations, which may vary. Consult this website for more information on your local requirements:

    Common Steps for Managing and Disposing of Empty Pesticide Containers

    • Triple Rinse or Pressure Rinse

      • Fill the empty container about 1/4 full with clean water.

      • Replace the cap and shake the container vigorously.

      • Pour the rinse water into the spray tank and allow it to drain for 30 seconds.

      • Repeat this process two more times.

      Pressure Rinse

      • Use a pressure rinse nozzle.

      • Insert the nozzle into the container and rinse for at least 30 seconds, ensuring the rinse water is also added to the spray tank.

      Drain and Dry

      • Ensure that all rinse water is added to the spray solution to be used on the target area.

      • Allow the container to drain and dry completely.

      Disposal

      • Puncture or Crush: Once the container is empty and rinsed, puncture or crush it to prevent reuse.

      • Recycle: Participate in a pesticide container recycling program if available in your area.

      • Landfill: If recycling is not an option, dispose of the container in a sanitary landfill. Confirm with local waste management authorities about the acceptability and specific requirements for disposal.

      Label and Documentation

      • Keep records of the disposal process as required by local regulations.

      • Remove or deface the label to indicate that the container is empty and has been rinsed.

      Local Guidelines

      • Check with local agricultural extension offices, environmental agencies, or waste management authorities for specific guidelines and programs.

      • Follow any additional local requirements for disposal.

  • Always read and follow label directions on storage and transportation before buying or using a pesticide. Follow all appropriate federal, state, tribal and local regulations. The label is enforceable by law and every applicator has the legal responsibility to follow it.

    Proper storage and transportation practices for pesticide products are crucial for ensuring safety, preventing environmental contamination, and complying with legal regulations. Follow all storage instructions on the pesticide label. Here are examples of key practices and their importance:

    Proper Storage Practices

    Dedicated Storage Area

    • Store pesticides in a well-ventilated, cool, dry, and secure area away from living spaces and people that should not have access to the pesticides.

    • The area should be labeled and restricted to authorized personnel only.

    • Never store pesticides in cabinets with or near food, animal feed, or medical supplies.

    • Store flammable liquids outside your living area and far away from an ignition source such as a furnace, car, grill, or lawn mower.

    • Do not store pesticides in places where flooding is possible or where they might spill or leak into wells, drains, ground water, or surface water.

    Temperature Control

    • Maintain temperatures as recommended by the pesticide label to prevent degradation or chemical reactions.

    • Avoid storing pesticides in areas subject to extreme temperatures.

    Shelving and Containment

    • Use non-absorbent shelving materials, such as metal or plastic.

    • Store liquids below powders and granules to prevent contamination in case of leaks.

    • Contain potential spills with trays or secondary containment units.

    Proper Labelling and Segregation

    • Always store pesticides in their original containers with the label, which lists directions for use, ingredients, and first aid steps in case of accidental poisoning.

    • Never transfer pesticides to soft drink bottles or other containers. Children or others may mistake them for something to eat or drink. Use child-resistant packaging correctly.

    • Child resistant does not mean child-proof, so close the container tightly and keep it out of children’s reach.

    • Segregate different types of pesticides (e.g., herbicides, insecticides, fungicides) to avoid cross-contamination.

    Access Control

    • Lock storage areas to prevent unauthorized access.

    • Maintain an inventory log and regularly inspect the storage area for leaks or damage.

    Emergency Preparedness

    • Keep spill kits, fire extinguishers, and first aid supplies nearby.

    • Post emergency contact numbers and procedures in a visible location.

    Proper Transportation Practices

    Secure Loading

    • Secure pesticide containers upright to prevent tipping, spills, or leaks during transport.

    • Use suitable vehicles that can be easily cleaned in case of spills.

    Labeling and Documentation

    • Ensure that containers are properly labeled, and that transport documentation complies with local and national regulations.

    Separation from People and Animals

    • Do not transport pesticides in the passenger compartment of vehicles.

    • Keep pesticides away from food, feed, and other consumables.

    Environmental Protection

    • Avoid transporting pesticides in open vehicles during inclement weather to prevent exposure to rain or extreme temperatures.

    Spill Preparedness

    • Carry a spill kit and know how to use it in case of an accident.

    • Have emergency contact information readily available.

Rules and Regulations for Applying Pesticides with UASS

  • UASS flight operations and UASS pesticide applications are covered by different regulatory bodies for aviation and pesticide use, respectively, at the federal, state, and local levels. Pesticide applications with UASS must comply with all regulations required and the onus is on the applicator to know which regulations they need abide by.

    At the federal level, the Federal Aviation Administration (FAA), which is part of the Department of Transportation, regulates the aerial flight operations of UASS and there are specific requirements to be allowed to fly a UASS in the US. More information can be found on the FAA’s website and is listed below.

    At the federal level, CLA supports the EPA’s position to enable these technologies’ commercial use for products registered for manned aerial application since, in general, the anticipated UASS use pattern is covered by existing risk assessments, knowing that potential further data generation will facilitate their fit into the regulatory risk assessment process.

    As of August 2024, the EPA does not have an official policy for applying pesticides with UASS but allows for this use given that the product is registered for manned aerial application and all label language is followed for this application type and is not specifically prohibited. Additionally, the state needs to also allow for UASS pesticide application and any local requirements (e.g., government and tribal lands, county requirements, and other local laws) need to additionally be followed. Further information on EPA’s certification standards for pesticide applicators can be found here:

    Additionally, states are beginning to publish guidance and we’ve listed the resources we’re aware of below as of August 2024:

  • Check airspace and make sure you have authorization to fly and comply with any reporting needed to local authorities.

    Survey the field/site to be treated prior to the application to identify sensitive areas, including waterways, natural habitats, livestock, pollinators, adjacent crops, roads, obstacles such as power lines, no-fly zones (including where overlap with other-application types, such as manned aerial applications could potentially occur), etc. If possible and appropriate, do this by air and by ground.

    Clearly map obstacles on the remote control or using drone software before the flight to prevent drone crashes. Stay away from sensitive areas such as schools, airports, tall buildings, dense crowds, and do not fly above people. Additionally, ensure potential bystanders that might not realize spraying is going on such as hikers, children, walkers, bicyclists, agricultural workers, neighboring farmers, etc., are identified ahead of time.

    Notify bystanders of proper safety distances to be followed per local requirements and ensure the area to be applied is adequately marked to indicate an active spraying operation and exclude non-involved people.

Equipment

  • When considering drone equipment for pesticide applications, it is important to ensure that the drones are capable of performing the tasks efficiently and safely. Here are key considerations around safety, efficiency, accuracy, and reliability:

    • Data Collection and Analysis: Drones equipped with sensors and cameras can collect data on crop health and pest infestations, aiding in targeted and efficient pesticide applications.

    • Safety Features: Look for drones with built-in safety features such as fail-safes, emergency landing capabilities, and remote monitoring to enhance operational safety. Robust safety features and compliance with regulations protect operators, the environment, and surrounding communities from potential hazards.

    • Regulatory Compliance: Ensure the drone and its operation comply with local aviation and pesticide application regulations, including any requirements for pilot certification and drone registration.

    • Payload Capacity: Ensure the drone has sufficient payload capacity to carry the required amount of pesticide without compromising flight stability.

    • Spray System: The drone should be equipped with an advanced spray system that provides uniform coverage and allows for precise control over droplet size and spray rate. Ensuring the drone has the right capabilities improves the efficiency of pesticide application, reducing waste and operational costs.

    • Flight Time and Battery Life: Consider drones with long flight times and efficient battery management systems to maximize operational efficiency.

    • Navigation and GPS: High-precision GPS and navigation systems are crucial for accurate mapping, route planning, and ensuring precise application of pesticides. Advanced navigation and spray systems ensure pesticides are applied precisely where needed, improving crop protection and reducing environmental impact.

    • Obstacle Avoidance: Drones should have robust obstacle detection and avoidance systems to navigate safely around trees, buildings, and other obstacles.

    • Weather Resistance: Choose drones that can operate in various weather conditions, including wind, rain, and high humidity, to ensure reliability and safety during pesticide applications. Choosing drones with good weather resistance and easy maintenance ensures consistent performance and minimizes downtime.

    • Ease of Maintenance: select drones with easily replaceable parts and accessible maintenance features to minimize downtime and ensure consistent operation.

  • The uniformity/quality of application is critical in achieving the best performance possible while minimizing off-site movement (drift), including nozzle/droplet selection and effective swath, which is directly linked to how the equipment is calibrated. The calibration procedure is an important step in minimizing variability, ensuring the best pesticide deposition, and reducing drift so the proper dose is delivered to the target insect pest, disease, or weed while minimizing off-site movement.

  • The manufacturer’s recommendations should be followed. At a minimum, calibration should be conducted at the start of the season, prior to starting a new job that requires a different equipment set up (different crop, pest, product, etc.) and when changes or repairs to the equipment are made (boom configuration changes, nozzles replaced, new pump, etc.). Additionally, calibration could be recommended by the manufacturer after a specific distance of travel, and anytime any major fixtures or settings are changed on the drone.

  • Effective Swath Width (ESW) drives application rate, how long it will take to complete your application, and overall effectiveness of the application. The manufacturer’s statement can differ from the actual ESW (for example because of real-time environmental conditions) so it’s important to do so in the field.

    ESW is measured by spray deposition along the swath to ensure good calibration and determine the application volume rate. It is a fraction of the total swath width, which is the linear distance of the spray footprint during a single pass.

    Factors Affecting Swath Width:

    • Nozzle type and pressure

    • Nozzle position and orientation

    • Spray release height

    • Flight speed

    • Rotor downwash vortices and aircraft wake

    • Environmental conditions like wind direction and speed

    • Adjuvants such as drift reduction agents and deposition aids can also impact ESW.

    Measuring ESW:

    • Use media like water-sensitive cards or dye-stained samplers placed across the flight path

    • Capture images with a digital camera or scanner and analyze coverage data using computer programs or mobile apps

    Calculating ESW:

    • Determine coverage as a function of distance to the centerline

    • Calculate the coefficient of variation (CV) from multiple swaths

    • ESW is typically the largest swath where CV is 25-30% or lower

    Equipment and Expertise: The process can be complex and may require specialized equipment and professional help.

    Further information can be found at sources like:

  • Proper tank cleaning is crucial to prevent contamination of subsequent sprays, potential crop damage, and issues with tank mix compatibility or product safety. Label language should be followed, and instructions can be found in the storage and disposal part of the label.

    Operators must be cautious of interactions with the UASS, including filling, battery changes, minor repairs, and transportation. These activities involve risks from machinery components like electricity and propellers. Proper procedures and PPE, like gloves and protective clothing, are essential to minimize exposure, especially when dealing with nozzle blockages, which often require direct contact with the UASS. Regular training and adherence to safety protocols are crucial for safe and effective drone pesticide applications.

    After each use, drone application equipment must be thoroughly cleaned to remove residues internally and externally. At the end of each day, flush the spraying system with appropriate cleaning agents: water and detergent for water-based sprays or solvents for oil-based sprays. Cleaning procedures can be product-specific or drone manufacturer-specific, so it’s essential to follow specific guidance.

    The typical cleaning method involves a triple-rinse procedure, where the spray tank is partially filled with clean water, shaken, and emptied into a designated disposal area. This process should be repeated three times. Similar cleaning protocols apply to spray nozzles, pumps, and tubes, and fixed-tank drones can follow a similar triple-rinse method, ensuring no water is forced into electronic parts to avoid malfunction. Dispose of the rinsate properly and in accordance with the label (such as spraying back over the application site) and not in waterways or near ditches.

    Additionally, care must be taken when handling wettable powders to prevent residue buildup in spray lines and filter housings. PPE, as specified by product labels or regional regulations, should be worn, cleaned, dried, and stored properly.

  • Label PPE language should be followed, which often includes the use of gloves and protective clothing, and potentially unique areas of drone applications compared to other conventional applications should be taken into consideration. This includes the presence of residues on UASS equipment, including batteries and the water that batteries may have been cooled in, which if the batteries have residues on them, this water is considered chemical waste and should be properly handled along with container rinsate at the end of a job (see cleaning and maintenance section).

    Batteries rely on a power source that stores a high amount of energy in a small space (i.e., high energy/density). Lithium cells provide sustained power and often have the capability to recharge. When designed, manufactured, and used properly (such as keeping cool), lithium batteries are a safe, high energy density power source for devices in the workplace. While lithium batteries are normally safe, they may cause injury if they have design defects, are made of low-quality materials, are assembled incorrectly, are used or recharged improperly, or are damaged.

    It is important to ensure that workers who use or handle lithium-powered devices, cells, or batteries in the workplace receive training associated with these products. In cases where batteries are cooled in a water tank, consider residual pesticide spray being on the batteries from the prior flight and is now in the cooling tank. Dispose of this water as instructed by the label for pesticide contaminated water. Additionally, and specific to batteries, there could potentially be additional safety precautions to observe (for example in the USA, these are outlined by OSHA).

Efficacy Considerations

  • A certified pesticide applicator and/or local extension and/or state agent will have guidance on the options to be used to treat pests, diseases, and/or weeds, including if the issue is being identified properly, present at potentially damaging levels, and at a stage able to be controlled. It needs to be ensured that the labeled uses on the pesticide to be utilized matches with the pest and use site. Select the appropriate product(s), use rate(s), application volume rate, and timing based on crop and pest/disease/weed stage. If mixing multiple products, conduct a compatibility test prior to mixing as low water volume mixtures used in UASS application may magnify any incompatibilities between products.

  • In addition to the factors above, including following all label instructions and local regulations, and assuming proper calibration and ESW, monitor the weather conditions expected at (and during) the application, avoid spraying if wind speed is under 3 mph/5 kph or over 10 mph/16 kph, local surface temperature inversions exist or if rain is approaching. Do not spray if wind speeds exceed flight parameters for the UASS. High temperatures and/or low humidity may require increases in application volume rates, increases in target droplet size or use of adjuvant to reduce evaporation.

    Choose the application volume rate, nozzle type, and other spray parameters such as aircraft height and nozzle/ atomizer positions that deliver the product to the target while minimizing off-target movement (drift). While for UASS, best practices for minimizing drift are still being developed, there are general guidelines that can be followed such as not flying too high above the target application area, using nozzles that give coarser droplets, not applying during high wind situations, and using a quality, calibrated UASS. Avoiding applications under local surface temperature inversion conditions is also important. Modeling efforts specifically for UASS are underway and it will be possible in the future to more specifically characterize the parameters that affect spray deposition and thus to provide more precise recommendations.

    Please see section on environmental and application equipment variables to better understand how decisions on spray set up selection can help you reduce drift while maximizing control.

    • The basic need for adjuvants does not change between ground, aerial, and UASS applications.

      • This includes the use of water conditioners, pH modifiers, compatibility aids, surfactants, and drift reduction agents.

      • High Surfactant Oils (HSOC and HSMSO) may be better suited than traditional MSO and COC based on the limited liquid carrier volumes being used.

    • Adjuvant selection should be based on the pesticide product label(s) recommendation(s) and formulation type(s).

      • Knowing your Effective Swath Width is extremely important, particularly when using a drift reduction agent, to prevent skips and streaking.

      • Influence of nozzle type/design and pesticide formulation type, on the desired droplet spectra should also be considered when selecting and using a drift reduction agent.

    • Pay special attention to Mixing and Loading procedures!

      • The lower water volume used in drone applications can lead to lack of compatibility, as there is just less water to solubilize the pesticides.

      • Agitation is extremely important in keeping anything other than soluble liquids in suspension.

        • Mixing a large volume of complex tank mixes should be avoided unless constant agitation and or recirculation is available.

        • Lack of agitation will lead to product separation, crop injury, reduced efficacy and plugged screens and nozzles. Sloshing during transport is not the same as agitation.

        • Mix only what is needed for the immediate application, or what can be sprayed within 30 minutes of mixing if agitation and recirculation are unavailable.

        • Use of a compatibility aid is highly recommended, but it does not replace the need for agitation and proper mixing order.

Environmental Variables

  • Applicators must follow product label instructions, observe buffer zones, and consider additional weather factors like precipitation and target pest activity for effective and safe applications.

    Successful UASS pesticide applications require consideration of environmental factors such as wind speed, temperature, and humidity, along with adherence to product labels and local laws to minimize off-target exposure.

    Wind speeds below 3 mph or above 10 mph increase drift potential, necessitating adjustments like larger droplet size and drift-reducing agents. High winds can also destabilize UASS, compromising spray accuracy and safety. Measurements should align with international standards, and spraying should avoid high winds, especially towards sensitive areas. Optimal environmental conditions, including appropriate wind speeds and directions, are crucial for effective on-target spraying.

    Hot, dry conditions increase drift risk due to evaporation, requiring larger droplets and higher application volumes. Spraying during cooler times can help, but care is needed to avoid thermal inversions, which trap warm air and increase drift. Adjuvants can reduce evaporation, and local experts and product labels should guide their use. Surface temperature inversions, indicated by mist or fog, should be avoided as they cause lateral movement of spray droplets.