By Vicky Boyd
While drones have made inroads into aerially mapping farm fields and even applying beneficial insects, they have yet to gain the same traction spraying pesticides and other crop production materials.
Limited by payload size, battery life and pesticide labels, drone application so far has been mostly relegated to hard-to-reach areas, spraying high-value winegrapes in hilly terrain or spot spraying specialty crops. In the meantime, a number of companies continue to develop and test larger craft with bigger payloads.
San Joaquin Farm Bureau Second Vice President James Chinchiolo, who farms cherries and walnuts with his father near Lodi and Linden, respectively, has already taken to the sky. He’s used his own drone to fly their walnut orchards to map for stress and also hired a drone company to fly in cherry orchards looking for stress.
Viewing the technology also as a time-saver, Chinchiolo said he’s used it to check the progress of pruning crews.
“It’s going to take me 20 minutes to walk it or I can just send my drone to go over and get an aerial record in a few minutes,” he said.
While Chinchiolo admits he doesn’t have a sense of where drone technology is heading, he said he could ultimately envision “dronification” of heavier aircraft application equipment. By this, he meant converting full-sized fixed-wing airplanes or helicopters into autonomous spray craft.
Not only would it mean they could apply the higher volumes of materials that many growers want or that product labels require, but Chinchiolo said it also would improve safety by removing the pilot from the cockpit.
“If we do ever get to that point where some of these drones are much, much bigger, then all of a sudden they’re taking up 200, 300 or 400 gallons of material. That would be a game-changer,” he said.
The industry isn’t there yet. But a partnership inked in 2022 between Wilbur Ellis and Guardian Agriculture is inching closer with a U.S.-built electric autonomous vertical take-off drone, the SC1. Powered by a 40-horsepower drive train and four 6-foot propellers, the craft is touted as having a 20-gallon payload. It is equipped with a 16-foot spray boom and is advertised as having an application rate of 40 acres per hour, including tank refill and supercharging.
The Federal Aviation Administration and California approved use of the SC1 drone earlier this year, and it’s scheduled to be deployed initially in the Salinas Valley. Woburn, Massachusetts-based Guardian also has begun taking orders for the drone, which starts at $119,000.
Applying beneficials by air
Hardly a newcomer to unmanned aerial vehicles — as drones are also called — Salinas-based Parabug has used them to carry patented dispensers to apply beneficial insects to orchards, vineyards and row crops since 2016. Now with customers in California, elsewhere in the United States and Australia, the company uses both in-house pilots and a network of service providers that meet its strict requirements, said Parabug general manager Jaclyn Bennett.
In addition, all pilots must have appropriate FAA and state licensing and undergo extensive training on topic, such beneficial insect care and handling and quality control.
Parabug just provides drone application and is insectary agnostic, leaving the choice of insect-rearing facilities up to the customer. Once the pest and related beneficial control are identified, customers go online to create a digital application map in a matter of minutes. They review the map, order the beneficials and schedule an application. Depending on proximity between ranches and weather conditions, an operator can typically cover 300-500 acres per day.
The Lodi Winegrape Commission and Parabug held a family field day at Lodi’s Michael David Winery in 2019 to show off the technology and educate entire families about biological control.
Parabug went on to conduct trials with the commission that year and continues to work with a number of San Joaquin County growers, said Bennett, also a licensed pest control advisor. The trials were part of a larger demonstration project where the commission looked at pheromone mating disruption and beneficial insects to control vine mealybug, which spreads leafroll virus. At the time, the project involved releasing Cryptolaemus montrouzieri, a predatory beetle also known as the mealybug destroyer, and a minute parasitic Anagyrus wasp. And interest in harnessing beneficial insects to control pests has only grown, Bennett said.
“Beyond just Cryptolaemus and Anagyrus, we’re seeing grape growers using lacewing for leafhopper and as a generalist predator as well as predatory mites for spider mites,” she said. “There’s been an increase in interest in predatory mites in walnuts along with other San Joaquin County crops that struggle with spider mites such as almonds, beans and melons.”
Bennett said drones have gained on ground application using an ATV and blower for a number of beneficial insects.
“In all cases, we can expect applications to be faster and more uniform,” she said of drones. “Additionally, since we’re applying from above, we’re putting those insects right where growers need them — into the canopy. In orchards, particularly, placement in a large canopy such as walnuts is important.
“With ATVs, there’s always a concern about damage when they’re blown out. When we’re applying them, the bugs don’t have any force on them, which is a significant benefit.”
In addition, she said ATVs typically skip rows, applying the insects to every third or fifth row, for example. But the drones dispense the beneficials uniformly over the top of the entire the block.
The California Alliance with Family Farmers has been working with drone-application of predatory mites as part of its Biologically Integrated Orchard Systems on-farm demonstration projects since 2022. One cooperating walnut operation was near Stockton.
Hanna Kahl, CAFF’s ecological pest management specialist, said drone technology holds promise. But it comes with several caveats, including application rates, appropriateness of the beneficial to the pest and how widely beneficials will disperse.
And drone application may not fit every operation, particularly smaller-scale ones that don’t have the acres over which to spread the cost to make it economical.
“I really think every farmer has to figure out what works the best for them, and the answer isn’t going to be the same for each one,” she said.
While drones may save labor, Kahn said there are benefits to having someone walk the orchard to apply predatory mites manually as CAFF did in some of its trials. They have boots on the ground and can scout for pests or other issues at the same time.