The newest tool in the fight against rapid ohia death: A chainsaw mounted on a drone

HONOLULU (HawaiiNewsNow) - University of Hawaii at Hilo Professor Ryan Perroy’s fight to save Hawaii’s ohia trees is a task that requires pinpoint precision.

“Ohia trees can die for all kinds of different reasons,” he said. “You can’t really tell at this point why until you get that physical sample.”

Physical samples are cuttings from Ohia trees that show signs of rapid ohia death, the fatal condition caused by fungus. Until now, crews could only access diseased trees on foot.

“Sometimes we’ve identified trees that we think are infected with the fungal pathogens responsible for rapid ohia death but we can’t get to them on the ground,” he said.

That’s where the new device comes in handy. It’s a chainsaw mounted on a drone.

Licensed pilots fly it into forests where rapid ohia death is occurring to collect cuttings.

The cutting-edge method is just getting off the ground.

“We haven’t deployed it for miles and miles away from where our crews are at this point. I think as the regulations change we’ll have the capability of doing that,” Perroy said.

The chainsaw clips branches from sick ohia trees, that are then tested for presence of the deadly fungus. Samples need to come from large limbs to be accurate.

Perroy and his team teamed up with researchers in Switzerland and R&R Machining/Welding in Hilo to perfect the chainsaw drone device that was named Kukuau.

“Kukuau is a type of crab. Because the device has a claw that is sort of natural. Kukuau is also the name of an ahupuaa here in Hilo, so it also reflects its place of origin,” Perroy said.

Since 2016, his team has monitored plots of ohia trees on the Big Island where rapid ohia death was detected.

“In essentially all of those plots we continue to see cases of mortality, so it hasn’t stopped. It’s continuing,” he said.

That makes this chainsaw drone a very important tool for pinpointing the tree disease. And it can also help to keep forests from being disturbed by human intrusion.

“The hope is that these types of things can be used to keep people safe, so they don’t have to go out in the forests to do other things. We can have these types of devices carry out these tasks,” Perroy said.

The faster rapid ohia death is diagnosed, the quicker land managers can decide on how to protect surrounding ohia trees that are still healthy.

Copyright 2022 Hawaii News Now. All rights reserved.