Scientists Are Using Drones to Combat a Fungus Wiping Out Hawaii’s Sacred Trees

A fleet of drones with built-in saws could be the future of forestry

Chris Baraniuk
OneZero
Published in
5 min readOct 17, 2019

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Photography: UH Hilo SDAV Laboratory

InIn early September, a drone flew over the Waiakea Forest Reserve on Hawaii’s Big Island. It slowed its pace, lowered itself to a hover just feet from the canopy, and readied a device attached to its undercarriage. Two plastic “arms” rotated gently, grabbed a small branch, and, using a built-in saw, chopped it off. Having collected the sample, the drone flew away.

This could be the future of forestry. The operation, conducted by Ryan Perroy, a geographer at the University of Hawaii at Hilo, is part of a rescue mission to save a special tree — the sacred ʻŌhiʻa (pronounced “oh-HEE-ah”) that blankets Hawaii’s islands. For many Hawaiians, the ʻŌhiʻa is a symbol of nature, an ecological backbone, and the very essence of the forest. But the trees are under attack.

“It really is probably the most devastating thing I’ve worked on in my career.”

The U.S. Department of Agriculture (USDA) Agricultural Research Service, the USDA Forest Service, and the University of Hawaii at Manoa first identified a tree-killing fungus on Hawaii Island back in 2014. Last year, researchers from the University of Pretoria and other institutions confirmed in a scientific paper that there are two species of fungus causing havoc — and both are new to science. There are now 1,600 confirmed detections of the disease on the Big Island and 100 more cases across the other islands.

“It really is probably the most devastating thing I’ve worked on in my career,” says Lisa Keith, a plant pathologist at the USDA who has been stationed in Hawaii for nearly 20 years.

The fungus is a strangler. It causes a disease known as Rapid ʻŌhiʻa Death, which works its way into the vascular system of the plant and cuts off the internal water supply, starving the tree. Within weeks, the tree’s leaves turn a dull red-brown. Black smudges appear in the sapwood. Eventually, the leaves fall off, leaving a skeletal claw of diseased wood behind. The lifeless core of the tree, still reaching skywards, is doomed to rot. There is no known cure for the infection.

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Chris Baraniuk
OneZero

Freelance science and technology journalist. Based in Northern Ireland.