Drone technologies, also known as autonomous aircraft, are being developed for many different purposes. This week an important milestone has been announced concerning the use of autonomous, electric, aerial sprayers for pest management in the banana industry. A startup company named Pyka has been working with the major fruit and vegetable company, Dole, to evaluate these drones for making the fungicide applications that are critical to that production system, and phase I results are very promising.
Bananas are a very tasty, convenient, nutritious component of the modern diet. They are the third most available fruit crop in the US and the number one fruit in terms of fresh consumption (see graph below).
Bananas are counter-top storable, very kid-friendly, and an excellent source of potassium. They can only be grown in the tropics, but they can be transported to markets like the US using highly efficient ocean transportation which has a low carbon footprint, generates additional income through the “back haul,” and helps to make them very affordable for consumers. All of this is possible because of a finely tuned system based on the Cavendish variety that saved the industry when the previous banana of commerce was being wiped out by a soil-born fungal pathogen that caused Panama Disease back in the 1950s. Yes, this is a “monoculture,” but there are good reasons that this is necessary for this crop. For this system, Cavendish bananas are harvested at just the right stage of still-green maturity, held at very specific temperatures on the ship, and exposed to the right amount of the natural plant hormone ethylene in “ripening rooms” close to the final retail destination. This only works if the growing bananas are protected from a fungal disease called Banana Sigatoka.
The Sigatoka fungus does not directly infect the fruit, but if there is too much infection of the leaves of a given tree, the fruit harvested from that tree will start ripening on the ship and that entire container will arrive in our ports in the blackened, “over-the-hill” state that we have all observed if we leave the fruit too long on the counter.
To keep the disease in check, the trees must be treated with fungicides on an almost weekly basis, and those sprays are mostly applied using airplanes. The fungicides that are used have very little toxicity to people or animals, but this process is challenging and somewhat dangerous for the pilots, and it is very hard to avoid having some missed areas, spray overlaps, and at least some off-site drift. Organic banana production isn’t a solution because it is only possible in the limited tropical regions that are dry enough to make it feasible to control Sigatoka disease when limited to the organic pesticide options of extensive sprays of mineral oil and the one plant extract which is approved for use on organic (although that product has more eye and skin irritation issues and more aquatic invertebrate effects than many of the conventional fungicide options).
Bananas are unusually difficult to breed, and although biotech solutions such as moving resistance genes from wild bananas are a theoretical solution, that approach is effectively “off the table” because of anti-GMO influence. Fungicide sprays are the only viable alternative. That is why the banana industry is very interested in the potential for doing the spraying with autonomous drones.
Pyka was founded in 2017 by an entrepreneur named Michael Norcia who followed a life-long passion for aviation, sought training in physics and computer science, and who initially worked with companies seeking to develop autonomous aircraft for human passenger transport. Seeing that such a technology could take decades to develop, Norcia chose to focus on more realistic nearer term applications for cargo and agriculture.
They have developed electric powered, lightweight carbon fiber drones with the capacity to do the spraying. Pyka and Dole have been doing the initial “real world” testing with Pelican Spray aircraft on banana plantations in Honduras. The drones they tested have a 38 foot wingspan but only weigh 1300 pounds, about half of which is the batteries. The drone can travel at 80 miles per hour at 9 feet above the tree canopy. This is a larger capacity unit than most existing agricultural drones.
The Pyka drones can spray for about 15 minutes at a time after which the batteries are swapped by one staff member while the other refills the fungicide spray tank. That is about the same level of staffing as for a manned aerial application, but the roles are much less stressful or dangerous. There are 4 batteries per drone with 3 charging from the grid at any one time. They don’t draw a great deal of power – about the same as for typical water pumps in those settings. They don’t require a runway like a fixed wing spray plane, and they can do a much more precise job of fungicide application because they are guided by RTK systems – a sort of super GPS with spatial accuracy down to the 1cm level. The drone is equipped with a way to measure wind speed and direction with extreme accuracy and compensate as needed. The rotors that fly the drone are sufficiently above the spray nozzles to avoid any interference with the spray pattern.
The horticultural experts at Dole are very satisfied with the disease control in the drone-applied test plots and the company is moving into phase II trials which will evaluate the cost savings potential of the more accurate spray pattern. Pyka is expanding its development to other crops as the overall regulatory climate for agricultural drone usage is progressing rapidly across regions – particularly in Brazil but also now in the US where the Pyka technology has recently been approved by the FAA.
So the good news is that we will continue to have an abundant, affordable supply of bananas and the job of making that possible may become more efficient. Drones will also become a more common technology for agriculture in general.
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