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Agronomic Crops Network

Ohio State University Extension


Drones for Spraying Pesticides- Part 2: Opportunities and Challenges

Photo by Erdal Ozkan, The Ohio State University.

Currently, there is tremendous interest in using drones to spray crop-protection products. Drones are now a viable option when choosing equipment to spray pesticides, and the number of companies offering drone spraying services is rapidly increasing in Ohio and other places in the United States. A variety of names and the acronyms are associated with remotely piloted aircraft. Most used ones are: Unmanned Aerial Vehicle (UAV) and Unmanned Aerial System (UAS). However, the name used most commonly by the general public is “drone”. So, I chose the same name as I refer to this type of aircraft.

An article appeared in an earlier edition of this newsletter ( gave a brief overview of different types of drones used for spraying pesticides, including the major components of a spray drone, as well as operating characteristics of spray drones. This time, I will focus on the opportunities spray drones bring us as well as their limitations, and the challenges facing drone sprayer operators.

As I mentioned in the previous article, a rapid proliferation of lighter, easy-to-operate drones for spraying pesticides is currently underway. They are lightweight but powerful enough to lift a 10–15-gallon tank. Most commercial spray drones today are the multi-rotor type shown in the picture below:

Commercial spray droneOpportunities spray drones provide us:

Using drones to spray pesticides is becoming an attractive option to many mainly for the six opportunities they provide: 1) The topography do not allow the use of traditional ground sprayers or conventional agricultural aircraft, 2) when airplanes and helicopters are not available or are too expensive to use, 3) drones more efficiently spray small, irregular-shaped fields, 4) when portions of a field cannot be reached by large, heavy ground sprayers because the soil is too wet, which happens frequently in some parts of Ohio, 5) drone spraying may be the best choice to avoid soil compaction and crop damage caused by ground equipment traffic when spraying fields with established crop canopies. Even after the wet ground dries enough to allow the large ground sprayer to get in the field, the sprayer is likely to cause a significant level of soil compaction resulting in reduced crop yield, and 6) drones significantly reduce the risk of applicators being contaminated by the pesticides. There are also emerging problems, such as tar spot on corn, which may increase the need for aerial pesticide application by drones.

Unanswered questions about spray drones:

There are many types of drones used for spraying pesticides. They all have similar components, but unfortunately no standards exist for the most optimum spray drone design, especially related to the location and configuration of nozzles on the drone. As a result, drone purchasers are faced with a number of unanswered questions:

  • Is it better to have a drone with a boom under the rotors, or is it better to have nozzles directly under each rotor?
  • If a boom is better, what should the boom width and its distance from the rotors be?
  • If having nozzles at the end of a drop-down hose under each rotor is a better option, what should be the length of the hose?
  • What are the best type of nozzles to put on drones for different spraying jobs?
  • Is there an optimum distance between nozzles?
  • Should there be one nozzle at the end of the drop hose, or multiple nozzles?

So far, drone configurations do not have the standardization seen in conventional, piloted aerial aircraft. This is because no well-designed experiments have been conducted, or models developed, to determine the most optimum drone design parameters to minimize spray drift and to maximize deposition and spray coverage on the target.

Limitations of spray drones and obstacles to their adoption

Acceptance of spray drones by individual farmers has been slow for several reasons:

  • Not enough research data comparing drone performance (e.g., efficacy and spray drift) to ground sprayers and conventional aircraft is available. The limited published data on performance of spray drones may not be usable and can be contradictory because of the wide variation of design parameters among drones being tested.
  • Fewer acres are covered per hour of operation compared to airplane and ground sprayers.
  • The battery powering the drone lasts a short time (5–15 minutes with a full tank) and requires recharging between tank refills. Having three charged batteries per drone and fast charging at 240v eliminates long interruptions in spraying to charge the drone’s battery. Maintaining three charged batteries allows replacement of a discharged battery while refilling the spray tank. The spent battery can then be recharged and ready for the next refilling.
  • The FAA imposes several operational restrictions on drones, such as: a drone must weigh 55 pounds or less including its payload, the pilot flying the drone must maintain a visual line of sight with the drone, permission must be obtained when flying in restricted air space, and drones can be flown only from 30 minutes before sunrise to 30 minutes after sunset. Perhaps the most severe restriction is that an operator can fly only one drone at a time. However, swarm spraying is practiced legally and successfully in other parts of the world, especially in southeast Asia, mainly China, South Korea, and Japan. Fortunately, the FAA allows pilots to apply for waivers for several of these limitations, such as the 55 lb maximum weight of the drone sprayer, night spraying, and maintaining a line of sight.
  • Chemical product labels do not provide clear information related to drone spraying. Some labels do not allow aerial application of any form. Some labels allow aerial application of the product, but don’t specify the type of aircraft that can be used. Currently, no pesticide label provides specific instructions on how the product can be sprayed using a drone. It is anticipated that pesticide labels will eventually refer to drone spraying. The EPA allows drone use for spraying if the pesticide is already labeled for conventional aerial application and if FAA rules for operating drones are followed.

Future of Spray Drones

 Drone sprayers will never replace ground or conventional aerial application technology, but they may complement existing spray practices because of the opportunities they provide as mentioned earlier in this article. The future of drone spraying will be mainly affected by the economics, timeliness of crop protection (i.e., which option may get the job done in the shortest time), the type of spraying to be done (broadcast vs. targeted), and availability of local companies offering drone spraying. Although drone spraying does not seem to be a viable option to compete with ground sprayers with wide booms and conventional, piloted aircraft in the application of pesticides to large fields, some companies offering drone spraying indicate that their rates are competitive with or even more economical than the cost of spraying done by ground equipment and conventional aircraft.

Acceptance and adoption rate of spray drones by individual farmers is likely to increase in the near future due to following changes in regulations and technological upgrades:

  • FAA regulations and restrictions on use of drones may be eased, especially restrictions on “swarming,” in which multiple drones are operated by one pilot or autonomously.
  • Improved design and manufacturing may result in longer lasting batteries, wider spray width, higher flow rates, and faster operational speeds.
  • Larger drones with larger sprayer tanks may be designed and possibly approved by the FAA.
  • Upgrades to drone technology may result in improved variable-rate application, precision spot spraying and route planning, and better obstacle avoidance.

Additional information is in new OSU Extension Publication

An important topic that is not covered in this article in detail is the Federal (FAA) and State regulations related to using drones to spray pesticides. Two certificates must be obtained from FAA to spray using drones: an FAA “Part 107 Certificate” to fly a drone, and a “Part 137 Certificate” to apply pesticides using drones, or to apply pesticides using drones while under the direct supervision of a person who holds this certificate. However, spraying pesticides in Ohio requires more than these two FAA certificates. An applicator must also complete the Ohio Commercial Pesticide Category 1 training course, which covers “the application of pesticides, except fumigants, by aircraft.”  Detailed information on how to obtain these licenses and links to some resources on this topic are given in a new Ohio State University Extension Publication FABE-540 entitled “Drones for Spraying Pesticides— Opportunities and Challenges. The link to access this publication is: The PDF version of the publication is also available at:


Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.