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The Plant Health Instructor

Volume: 2022 |
Year: 2022
Article Type: Case Studies

​​Drift Away: Sprayer Technology Meets Apple Pest Management

​Olivia Meyer and Mark Gleason

Iowa State University - Horticulture, 006 Horticulture Hall, Ames, Iowa 50010, United States​

Date Accepted: 28 Nov 2022
 Date Published: 20 Dec 2022

Keywords: Disease Control, Pest Management


"Drift Away: Sprayer Technology Meets Apple Pest Management" is a case study designed for undergraduate students studying plant pathology, horticulture, entomology, sustainable agriculture, integrated pest management, and related subjects. The case draws on a simulated real-life scenario in which students place themselves in the role of the owners of a commercial apple orchard faced with a crisis involving adverse public reaction to drifting of pesticide sprays from the orchard to a nearby housing development. Students are asked to identify key considerations growers would need to address in solving this crisis and sustaining their business.

Among the available options are buying costly new sprayer technology that claims to reduce spray drift, developing a communication plan to mitigate neighbors' concerns, and taking no direct action and hoping for the best.

Kaelani and Terrel Davis are a mother and son who jointly own and manage their orchard apple orchard. Soon after the Davises had taken out a bank loan to expand their orchard to 20 acres, a housing development was built close to their home. A homeowner expressed concern on social media about the use of pesticides for orchard management so close to their home. Kaelani and Terrel are afraid that this social media post, which has now gone viral, will ruin their business. A friend mentioned a new sprayer technology that has the potential to minimize spray drift and lower the cost of pesticides by using less spray volume. They would be pioneers in their industry as one of the first growers to test the new technology, but the upfront costs are high, which would require an application for another substantial loan.

As students work through the case, they are presented with the challenges of determining how to handle public concerns about pesticide use as a small-scale grower in a smaller town that is seeing an increase in the number of people living there. They are also introduced to the role pesticides play in orchard pest and disease management strategies and the obstacles growers face in sustaining their farm enterprises.

Potential advantages for growers could be lower pesticide costs and fewer complaints from neighbors. However, the technology is still so new that few growers have experience with it. Should the Davises take the technology plunge? Meanwhile, how can they calm the social media storm?

Classroom Management/Suggestions on How to Use This Case

The discussion of this case study can be completed in a single class period with a class size of 5 to 40 students. A PowerPoint presentation can be used at the start of the class period to reinforce the class' prereading of the case by introducing the Intelligent Sprayer technology, the role of pesticide sprays in growing apples, public concerns about pesticide use, and how the new technology influences pest and disease management.

After the introduction (about 5–10 min), the class can be divided into groups to discuss how they would try to resolve the Davises' crisis, what kind of information the Davises would need to gather to help them decide what to do, and what their first actions should be.


This case study was tested in a 50-min introductory plant pathology class at Iowa State University. In postclass survey replies, most said that the activity was fun and engaging. They enjoyed learning about the new sprayer technology, the social media angle, and the importance of pesticides in apple production. They also appreciated the relatability of the Davises' story.

A common suggestion from students was the inclusion of some type of economic analysis to determine whether the investment in the new technology would be worth it. In response to this feedback, we added a mock quote of the cost of retrofitting the Intelligent Sprayer kit to Davises' conventional airblast sprayer. The exclusion of a detailed cost and benefit analysis allows the students to be more imaginative and explorative in their decision-making. In addition, an infographic and a link to a YouTube video have been added, addressing the components of the sprayer. Finally, several students would have liked to see alternatives in pest and disease management strategies aside from relying on pesticides. We have added additional information in the case study's background section that mentions alternative forms of pest management in apple orchards.​​


Learning Outcomes

  • Recognize how pesticide drift can impact commercial apple growers, their neighbors, and the environment
  • Explain how apple growers weigh risks and benefits when considering adopting new technology
  • Validate why effective pest and disease control is critically important in apple orchards
  • Devise ways to proactively communicate grower practices with neighbors and consumers​

Cast of Characters

  • Kaelani Davis (apple grower)
  • Terrel Davis (Kaelani's son)
  • Jojo Omeasoo (fellow apple grower)
  • @_safetyinsuburbia (person who recently moved into a nearby housing development)
  • Dr. Xin Hu (extension specialist and plant pathologist at research station experimenting with new sprayer technology)​​

The Case​

Figure 1. Paradise apple (Malus pumila) tree(s) in a commercial apple orchard in the U.S. Midwest. (Photograph by T. Davis Sy​dnor, The Ohio State University,, 2016)

Figure 2. Houses near an established apple orchard. (Photograph by Jonathan Billinger,, 2007)

Figure 3. Intelligent Sprayer technology (LiDAR sensor and GPS/flow controller) retrofitted onto an airblast sprayer.

Kaelani Davis grew up helping her p​arents take care of their small (5 acre) apple orchard next to their house located on the fringes of a city in the Midwestern United States. The demand for local produce in the city has skyrocketed since her parents operated the orchard. Kaelani, the only apple grower in a 50-mile radius, wanted to expand her business along with the city's growth. In the past four years, Kaelani and her son, Terrel, have increased the orchard's size to 20 acres and planted two new apple varieties (Figure 1). However, the city's expansion included developing a new housing complex directly across the road from her orchard (Figure 2).

One morning, Kaelani went out to apply an early-season pesticide spray. When she finished the spray and cleaned up the equipment, she went back to the house to take a shower and have lunch. As Kaelani walked through the back door, her son called her into the kitchen, sounding agitated.

"Someone on Twitter just called you out, Mom!" Terrel shouted. Kaelani looked puzzled and asked Terrel to explain.

"Someone called @_safetyinsuburbia just blasted you for using pesticides! She said she's worried about what our spray drift will do to her and her family. She's calling us out, Mom! This is going to ruin our business!"

Both Kaelani and Terrel knew that apples need protection from many damaging insect pests and diseases. Managing those threats required spraying an array of different pesticides throughout the growing season. At the same time, Kaelani was also aware that exposure to pesticides can harm people and the environment. She often worried that pesticide "drift"—wind-aided movement of pesticide spray away from the targeted apple trees—could land on her orchard workers and even her neighbors in the new housing development just across the road from the orchard. She always checked and rechecked weather conditions, such as the speed and direction of the wind before she sprayed. However, she had never anticipated that all those houses would pop up so close to her orchard.

Kaelani quickly called up her friend, Jojo Omeasoo, who also grows apples in the Midwest and had run into a similar issue with his neighbors. She asked him for advice on how to quickly resolve this escalating situation. Jojo told Kaelani about a new technology called the Intelligent Sprayer (Figure 3), which he'd seen at a grower conference last year. He said that this new technology could be retrofitted onto her existing sprayer. In experimental trials in apple orchards, the Intelligent Sprayer was much more accurate than a traditional "airblast" sprayer like the one Kaelani has always used. This meant that less spray was wasted as drift because more of it landed on the apple leaves and fruit. This new device's upsides were intriguing: she could save on spray costs by minimizing wasted spray and hopefully cut down on her spray-drift problem.

Jojo gave her the email address of the agricultural engineer at a nearby state university who had developed the Intelligent Sprayer and wished her luck.

Kaelani immediately contacted the engineer, Dr. Xin Hu:

Subject: New Sprayer Technology Q's

Hi Dr. Xin Hu,

My name is Kaelani Davis, and I am a local commercial apple grower. I have run into some issues with my neighbors, who recently moved into new homes adjacent to my orchard. They are telling me they can smell the pesticides from their property when I spray. They are concerned about their safety. I heard about some new technology on the market called Intelligent Sprayer that could fit onto my current airblast sprayer and improve the accuracy of my spraying. How does the technology work? How much does it cost? My orchard size is 20 acres. Do you think this new sprayer would be worth it for me in the long run?

Thank you for your time, ​

Kaelani Davis

The same day, a reply came back from Dr. Hu:

Subject: New Sprayer Technology Q's​

Hello Kaelani,

Thank you for your questions! The Intelligent Sprayer uses Light Detection and Ranging, or LiDAR, technology to "see" the apple tree. It can pick up on the tree's characteristics, like how dense the foliage is in the canopy and exactly where it is located. It can also tell if trees are missing in the row you are spraying. The sprayer's nozzles each turn on only when and where they are needed, so more of the spray hits the trees and less goes to waste.

In comparison, your current airblast sprayer is spraying without sensing where the apple trees are or how they look. As a result, the rate at which you apply pesticides is determined only by how fast you travel up and down the rows.

In our field trials, the Intelligent Sprayer cut the amount of pesticide spray by about one-third. Even with these savings, it provided good coverage of the trees and controlled insect pests and diseases just as well as a standard airblast sprayer. Less drift should mean fewer problems with your neighbors.

However, Intelligent Sprayer technology doesn't come cheap. A company that licensed the technology can overhaul your current airblast sprayer. But given the size of your orchard, the return on investment in the Intelligent Sprayer may take a little longer compared to a larger orchard. This technology is still very new, so there isn't much research on how well it works in Midwest apple orchards. If you invested in this technology, you would be a pioneer! On the other hand, the few growers who have converted to it have been pleased so far.

If you have any other questions, please don't hesitate to send me another email.


Xin Hu​

​Kaelani is torn. On the one hand, this new technology sounds like an attractive investment based on what Xin Hu claims it can do. On the other hand, she and Terrel recently took out a large bank loan to expand their orchard to its present size. Although she sells her produce primarily to the local co-op and does not run on a 'pick-your-own' style orchard, she's afraid that the recent event of being condemned on social media will cripple her business and prevent her from paying the mortgage on the orchard. She's worried that she'll lose not only her orchard but her home.


Outline an action plan that Kaelani and Terrel should use to meet these challenges. Explain your reasoning for each action.

  • What actions (if any) should they take?
  • What short-term and long-term factors should they consider before deciding whether to invest in the new sprayer technology?
  • How should they deal with their neighbors' perception of her orchard practices, whether or not they choose to purchase the new technology?
  • How could cancel culture associated with social media effect growers and influence grower practices in an industry designed to feed the world?​​


Sprayer Technology

The Intelligent Sprayer is a spray control system that uses light detection and ranging (LiDAR) technology to more accurately and uniformly apply pesticides to target crops. LiDAR technology uses data collected from reflected laser beams to map tree height, tree canopy width, and foliage density. In other words, this target-oriented technology can help the sprayer "see" the tree it is spraying and respond by spraying only what it sees. Growers can retrofit a simple add-on kit made up of several components (listed below) onto their conventional airblast sprayer (as opposed to buying an entirely new sprayer with new technology).

The kit is made up of the following items:

  • Laser sensor—Measures the shape and structure of each individual tree
  • Wi-Fi router—Helps transfer data from what the sensor has picked up to the tablet the operator controls from the cab of the tractor
  • GPS—Detects speed and position of the tractor during operation
  • Pulse-width modulated solenoid valves—Valves use electricity to regulate the flow of fluid
  • Flow controller—Used to activate the opening and closing of the valves
  • Tablet—Digital device used to allow the operator to control the spray system via Bluetooth

Field trials on apples have shown that this new spray technology—a type of precision agriculture that can control insect pests and diseases as well as conventional sprayers—uses 40–60% less pesticide by maximizing spray accuracy and minimizing off-target drift.

An infographic that provides more detail about the Intelligent Sprayer system and its technology is shown in the Appendix.

There is also a YouTube video that provides a short introduction and demonstration of the Intelligent Sprayer system that may be shown during the class period as a visual aid.​

Pesticide Exposure

Pesticides (fungicides, bactericides, insecticides, and herbicides) are widely used for managing pests, diseases, and weeds in many crops. However, improper use and application of pesticides can harm people and the environment. Pesticide exposure can happen when farmworkers mix pesticides before applying them, during spraying, and when spray drift lands on nearby workers, family members, or neighbors. Pesticides can also contaminate the air, water, and soil unless proper precautions are taken. In the United States, state agencies require pesticide-safety training and recommend using personal protective equipment to minimize the health and environmental hazards of pesticides.​


Spray drift is commonly associated with applying liquid pesticides in aerosol (droplet) form. The Intelligent Sprayer uses technology to 'see' trees to avoid wasting spray and improve targeting accuracy. In addition to the new technology, there are long-standing techniques for minimizing pesticide drift:

  • Wind can carry spray droplets off-site during an application. When applying pesticides, it is important to check the wind speed and direction to minimize the risk of off-target pesticide movement. Spraying during periods of moderate- to high-speed wind is not recommended.
  • The nozzles used on sprayers also impact the potential for spray drift. Nozzles can control the size of the spray droplets during pesticide application. Larger droplets are heavier, so they tend to be less affected by the wind than smaller droplets. However, using larger droplet sizes may lessen spray coverage and, thereby, reduce the effectiveness of the pesticide.​

Figure 4. Apple scab, a fungal disease caused by Venturia inaequalis. (Photograph by Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo,, 2021.)

Figure 5. The larva of a codling moth (Cydia pomonella). (Photograph by Whitney Cranshaw, Colorado State University,, 2018.)​​​​

Pest and Disease Control in Apples

Apples are one of the most economically valuable fruit crops per acre or hectare, but numerous pests and diseases attack this crop. The specific complex of pests and diseases that growers face is influenced by the geographic region where their orchards are located. Among the most widespread and serious diseases of apples in the United States are apple scab (Figure 4), fire blight, rusts, and powdery mildew. In addition, fruit rots and the sooty blotch and flyspeck complex damage the fruit. Major pest-insect concerns include codling moth (Figure 5), oriental fruit moth, European red mite, plum curculio, and many others. To meet the exacting market standards for blemish-free fruit, apple growers use pesticides as part of a diverse array of strategies that includes cultural controls, disease-resistant varieties, and biological controls.​

Background Questions

  1. How can spray drift affect humans and the environment?
  2. What meteorological conditions affect spray drift?
  3. What are the major differences between a conventional airblast sprayer and the Intelligent Sprayer?​​


  • Light Detection and Ranging (LiDAR) Technology: A method of remote sensing using light in the form of pulsing lasers that measure the distance between a source (the Intelligent Sprayer in this case) and the target.



Boatwright, H., Zhu, H., Clark, A., and Schnabel, G. 2020. Evaluation of the Intelligent Sprayer system in peach production. Plant Dis. 104:3207-3212.

Chen, L., Wallhead, M., Reding, M., Horst, L., and Zhu, H. 2020. Control of insect pests and diseases in an Ohio fruit farm with a laser-guided Intelligent Sprayer. HortTechnology 30:168-175.

Chen, Y., Zhu, H., Ozkan, H. E. 2011. Development of LiDAR-guided sprayer to synchronize spray outputs with canopy structures. Soc. Agric. Bio. Eng. 1110496.

Fox, R. D., Derksen, R. C., Zhu, H., Brazee, R. D., and Svensson, S. A. 2020. A history of air-blast sprayer development and future prospects. Transact. ASABE 51:405-410.

Kaine, G., and Bewsell, D. 2008. Adoption of integrated pest management by apple growers: The role of context. Int. J. Pest Manage. 53:255-265.

Mahmood, I., Imadi, S. R., Shazadi, K., Gul, A., and Hakeem, K. R. 2016. Effects of pesticides on environment​. Pages 253-269 in: Plant, Soil and Microbes. K. Hakeem, M. Akhtar, and S. Abdullah, eds. Springer International Publishing, Cham, Switzerland.

Salcedo, R., Zhu, H., Zhang, Z., Wei, Z., Chen, L., Ozkan, E., and Falchieri, D. 2020. Foliar deposition and coverage on young apple trees with PWM-controlled spray systems. Comput. Electron. Agric. 178:105794.