OAKVILLE — For two years, a different kind of visitor has shown up around a few Napa Valley vineyards – one equipped not with cash and a thirst for fine wines, but an ability to tend grapevines from above.
Now, the team that has tested unmanned aerial vehicles for pesticide and fertilizer spraying says a future of drone-aided agriculture is within sight.
On Wednesday, representatives of Yamaha Motor Corp. USA and the University of California, Davis, showed their handiwork, test-flying the Yamaha RMAX, a remote-controlled helicopter equipped with a sprayer at the university’s experimental Upvalley vineyard. Its designers hope to bring the technology to vintners and orchard farmers as early as next year, pending federal approval for commercial flights.
“There’s a number of areas to explore, but this is a good first step,” said Steve Markofski, a Yamaha spokesman attending the test flight. “The size of the plots, the high value of the wine-grape crop, those make Napa a good test bed.”
The flight demonstration, which was arranged by the Association for Unmanned Vehicle Systems International trade group, was the culmination of testing that began in August 2012 at the UC Davis experimental station in Oakville, as well as the nearby Robert Mondavi and Harlan Estate wineries, according to Ken Giles, a professor in the school’s biological and agricultural engineering department.
Yamaha has applied to the Federal Aviation Administration to clear its drone for commercial use, and hopes to begin leasing the helicopter to farmers as early as next year, said Markofski.
Fed by a gasoline-and-oil mix similar to weed trimmer fuel, the Yamaha RMAX clattered to life as a pilot fired its two-cylinder engine from a radio controller. Then the 9-foot-long, 220-pound chopper rose 10 feet from the Oakville station’s lawn before making repeated passes up and down nearby vine rows, smoothly heading back toward its pilot tail-first. Repeated passes produced a nearly identical path, which Markofski said results from the aircraft’s on-board GPS navigation system.
Hovering over a stand of vines, the drone emitted a fine water mist from its twin sprayers – nozzles that on a working aircraft can spread up to 61 pounds of seed, fertilizer, pest killers or other materials from a pair of tanks.
Driving such optimism is the FAA’s gradual embrace of unmanned aircraft for civilian tasks. Once largely restricted to military duties, the domestic use of drones took a major step forward Sept. 25 after the FAA cleared six companies to fly UAVs for video production and photography, records show.
But Markofski called the Napa Valley one of the best early candidates for drone-based farming – and pointed west toward the steep hillside vineyards of the Mayacamas Mountains as a prime reason why.
Spraying such farmland by air can eliminate the risk of tractors rolling over and injuring their drivers, he said, as well as allow spraying after rainstorms that leave steep-sided vineyards too slick and dangerous for wheeled vehicles.
“Tractors can’t work immediately after a rainstorm because of things like safety and soil compaction. Unmanned aircraft can,” he said before the flight, which took place a few hours after heavy rains passed through the area Wednesday. “You’re also physically removing yourself from the chemicals, so pesticide application is another (task) the RMAX is suitable for.”
How much aerial spraying can boost farmers’ productivity is not known, but field trials indicate the RMAX can spread substances up to 10 times faster than tractors or workers using hand sprayers, according to Giles, the UC Davis professor. The university is continuing to analyze flight data from the drone to measure its productivity and especially the accuracy of its spraying – an important factor in limiting the drift of chemicals.
“My interest is in payload delivery, and this is a new class of vehicle – not only as a vehicle but for spraying technology,” said Giles. “What I’m interested in is, can we decrease our pesticide use by doing more spot sprays with this?”
First flown in 1991, the RMAX has become a staple of rice farming in Yamaha’s home country of Japan as an aging population shrinks its rural labor supply. The company has sold or leased about 2,400 of the aircraft in Japan, and also offers them to farmers in Australia.
But because unmanned aerial technology has never been tried on a large scale in American agriculture, the company will initially concentrate on U.S. customers dealing with wine grapes and other high-value crops – and exclusively on a leasing model that includes training and upkeep, said Markofski.
“If we can get nice testimonials, it’ll be a wonderful thing,” he said. “But we’ll have to prove ourselves.”