Yamaha UAV finding role in Washington state cherry orchards

After providing precision spraying services in Japan’s rice fields for more than a decade, the Yamaha RMAX unmanned aircraft vehicle (UAV) could soon find a new role in the fruit tree orchards of Washington state. Through Washington State University’s Center for Precision and Automated Agricultural Systems and a private precision agriculture UAV firm, Digital Harvest, a project to utilize the RMAX over cherry orchards is underway.

Lav Khot, assistant professor for CPAAS, and Young Kim, Digital Harvest CEO, recently organized a demonstration of the RMAX for 15 orchard growers. To understand the reason for the demo requires understanding the complexities of cherry growing in the Pacific Northwest, according to Khot.

During the last two to three weeks of a sweet cherry’s time on the tree before harvest, the skin of the cherry is very thin. A rain event can leave water on the skin of the cherry that could lead to the skin cracking or splitting. If the cherry is split or cracked, it is not fit for sale. To combat the water buildup that leads to the cherry’s demise, orchard growers typically deploy a rented or leased helicopter that costs roughly $25,000 per month. The manned helicopters are flown roughly 200 feet above the tree tops. The downrush of helicopter air acts as a natural drying mechanism, pushing off or removing any water on the trees, essentially eliminating the possibility of cherry skin cracking or splitting due to moisture build up.

The recent demonstration near Prosser, Wash., involved RMAX deploying water on a section of cherry trees. After the water was deployed, the RMAX then hovered over the trees to show how it could also dry the water off. “Every year there are accidents with the [manned] helicopters,” Khot said. “It is not a very safe operation.”

The RMAX could supplement the use of helicopters to help eliminate cherry skin cracking, he said. Because the RMAX offers a payload capacity of 61 pounds, Khot believes the units could also be outfitted with high-resolution cameras or other sensors that would allow orchard growers to capture important tree health data.

Testing near Prosser will continue for the next few weeks. The demonstrations to date have only tested one cherry tree architecture structure, with other tests focused on other structures. Growers can plant trees that grow straight vertically or to one specific direction, Khot said, so their needs to be RMAX data to show if the UAV can be effective on all tree structures. “So far,” Khot said, “the testing looks promising.”

Autonomous flight paths will eventually deployed with the RMAX, he added. Flight height over the canopy would be vastly different than the manned options. The RMAX can fly as close as two feet above the canopy if necessary. Current testing will reveal the optimal height. Digital Harvest, a distributor of the RMAX is working to capture the demo data and provide the findings to Khot and the orchard growers.

In addition to the water removal efforts, Khot said the RMAX can also be used to do what more than 2,500 other units have or already do in Japan. “You can do surgical spraying as well. It is all very exciting.” 

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