Chainsaw packing drone helps Hawaii Island botanists fight ROD

Innovative botanists in Hawaii are once again adapting drone-loaded technology to save native plants from extinction in areas too remote or too dangerous for humans – this time on the island of Hawaii to control the Rapid ʻŌhiʻa Death (ROD) fungus fight that kills native ʻōhiʻa Lehua trees.

The new drone hack is the work of Ryan Perroy, a professor in the University of Hawaii, Hilo’s Department of Geography and Environmental Sciences, and director of the Spatial Data Analysis and Visualization program. A tireless DIY enthusiast, Perroy found a way to augment an existing UAV-borne device for cutting and collecting plant samples in hard-to-reach places with a twist Tobe Hooper would love — featuring a dangling chainsaw with a grasping robotic claw.

Read: Drones lead Hawaii’s rhino beetle fight

Unlike the original tool, developed by researchers at the Swiss public research university ETH Zurich, Perroy’s larger adaptation can saw off and retrieve larger cuttings that botanists in Hawaii need to accurately test for ROD – while also relying on the drone to ʻōhiʻa lehua to locate and trim places that are otherwise inaccessible.

If the method is effective in identifying and treating infected trees, it could prove crucial in saving the threatened and beloved native species.

ROD is a fungal disease first identified in Hawaii in 2014 and has since become a rapidly spreading threat, killing hundreds of thousands of ʻōhiʻa lehuas. Carried between areas on hikers’ clothing, animal fur, or even the wind, ROD clogs the tree’s system to circulate water to its canopy, leading to dehydration and death. Conservation of the species is essential for the balance of ecosystems and watersheds, as well as for the protection of certain cultural traditions centered on the species.

Back in 2019, Perroy heard about the Swiss drone attachment for cutting samples, but found it too small to bring back branch samples that Hawaii’s botanists need to accurately test for ROD infection. So he expanded his scale to include a chainsaw and an articulated robotic gripper to hold on to larger branches, and found local partners to manufacture them using 3D printing technology.

The result: While smaller air samples did not yield positive ROD results, a full 77% of larger diameter cuttings from the same trees showed the presence of the fungus.

“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,” said Perroy.

Read: Robotic arm flown by a drone is revolutionizing conservation of rare plants on Kauai

The adaptation of the device was funded by the Department of the Interior’s Office of Indigenous Relations, the National Park Service and Conservation X Labs. This was followed by Perroy’s work with various sensors on board drones to detect ROD on the island of Hawaii, which he further developed in parallel with the flying chainsaw method.

These aerial approaches are similar to the work of botanists on the island of Kauai. Their previous use of drones to identify native plants threatened with extinction on perilous cliff tops was recently carried out using a custom cutting unit to collect air samples for conservation and reproduction purposes.

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