New chainsaw drone technology is deployed to combat swift ʻŌhiʻa death

A new air chainsaw device that could help in the fight for salvation Hawaii‘s ʻōhiʻa Trees from a deadly fungal pathogen are put to the test by a university Hawaii at Hilo Geograph. professor Ryan Perroy and his research team have developed a drone attachment capable of taking branch samples for diagnostic laboratory testing and other purposes.

Close-up of grapple and chainsaw from above
The device consists of a small rotating chainsaw with a robotic grabber claw mounted underneath the drone

Dubbed the Kūkūau, the device consists of a small rotating chainsaw with a robotic gripping claw mounted beneath a drone and can cut and extract branches up to three inches in diameter. Samples are collected for diagnostic testing for forest fungal pathogens, including those responsible for Rapid ʻŌhiʻa Death (POLE).

“There were times when we spotted one ʻōhiʻa Tree suspected of being infected with the pathogens responsible for Rapid ʻŌhiʻa Dead, but because of the location, it was too dangerous or problematic to send field crews to test it for confirmation,” Perroy said. “Kūkūau has the potential to help in situations like this.”

The state-of-the-art device was developed by Perroy and his team in collaboration with researchers from ETH Zurich, a public research university in Switzerland, the US Department of Agriculture and R&R Machining/welding in Hilo Hawaii Island. Perroy’s research on tree branch sampling from the air was recently published and featured on the cover of the journal drones.

Three people with protective helmets and high-visibility shirts work on a drone in a field
From the left: AH Hilo researchers Roberto Rodriguez, Ryan Perroy, and Shawna Blackford activate drones

Project funding was provided by the US Department of the Interior’s Office of Native Hawaiian Relations, the National Park Service and Conservation X Labs. That AH Academy for Creative Media 3D printer used in the project.

Kūkūau is the name of one ahupuʻa (land subdivision) in the Hilo area and is also a term for a type of crab, Metopograpsus thukuharor ʻalamihi in Hawaiian.

Critical modifications

Person piloting a drone

researchers at ETH However, Zurich had previously developed a drone attachment capable of cutting small branches when the AH The Hilo team used the device and found that samples from twigs were often too small to detect the fungal pathogens. In July 2019, Perroy’s team worked with the Swiss researchers and a Hilo welding company to develop a new drone attachment equipped to saw off larger branches.

“We successfully detected the target fungal pathogen in the collected branches and found that branch diameter, leaf presence and condition, and moisture content of the wood are important factors for pathogen detection in sampled branches,” explained Perroy.

None of the smallest branch samples tested positive C.lukuohia, while 77% of the largest diameter branch samples gave positive results. The research shows that the new branch collector, capable of collecting larger branches, is the right size for a higher rate of successful diagnostic tests.

Since 2014, researchers have discovered POLE killed hundreds of thousands of adults ʻōhiʻa (Metrosideros polymorpha) on the Hawaiian Islands and is spreading further. POLE is caused by two invasive fungi, Ceratocystis huliohia and Ceratocystis lukuohiaand has the potential to irreversibly alter some native Hawaiian ecosystems.

More on this AH Hilo aerial survey research

Two people look at a computer monitor
AH Hilo researchers analyze data from aerial photographs to map problem areas

Perroy is the lead investigator at AH Hilo Spatial Data Analysis and Visualization Laboratory, a research unit that applies geospatial tools to local environmental problems Hawaii and the Pacific region. His group is working on the detection of POLE and invasive species populations across forests Hawaii with high-resolution cameras and other sensors carried by drones and helicopters. The images and data collected give managers valuable time to respond to outbreaks and give scientists better information on how diseases and invasive species are spreading.

In 2019, Perroy won $70,000 in a National Park Service-sponsored competition for his innovative use of drones and remote sensing devices for detection POLE. Over the past three years, Perroy and his team have refined and refined the equipment required to perform air sampling using a small unmanned air system.

crowns decimated Ohia trees
Rapid browning of those affected ʻōhiʻa treetops. (Image credit: Department of Land and Natural Resources)