Patient zero was probably in Puna, a lush, wild district not far from Volcanoes National Park on Hawaii鈥檚 Big Island.聽In 2010, the U.S. Forest Service and University of Hawaii started getting calls from distraught landowners in the area聽about ohia trees on their properties. Ohias,聽the聽bright, flowered trees that聽dominate聽nearly 50 percent of the island-state鈥檚 forests, are known for their ability to thrive nearly anywhere across the archipelago. But a swath of them had withered mysteriously and died in a matter of weeks.

It perplexed聽Flint Hughes, a Forest Service ecologist on the Big Island. Groves of aging ohia trees, which can live for 600 years, often die off together when they reach old age, but these were young trees that had turned brown and wilted. More calls started coming in from across Puna, all reporting the same problem: the ohias were dying, fast.

The Forest Service was stumped. It聽wasn鈥檛 until 2013, when Hughes and another ecologist聽checked聽on a particularly resplendent patch of forest owned and protected by the private Kamehameha Schools system, that the severity of the matter became apparent. The two men had been there a month earlier checking on seedling mortality. But rather than gazing at a grove of healthy trees, they stood over an ohia graveyard. The聽trees were alive a couple weeks ago,聽Hughes remembers thinking.聽鈥淭hat was the alarm going off.鈥�

Hawaii is a veritable bastion of sub tropic flora and fauna, and the Forest Service has addressed numerous ecological crises in the 57 years since the island cluster earned statehood. But whatever was killing the ohia threatened to leave much deeper wounds. The trees are a 鈥攖hey make up a huge majority of its canopy, and provide coverage for low-lying plants and food and habitat for honeycreeper birds鈥攁nd are central to native Hawaiian culture.

In ancient Hawaii, ohia was a byword for strength, sanctity, and beauty, says Sam 鈥極hu Gon, senior scientist and cultural advisor for the . Ancient Hawaiians used the tree鈥檚 strong wood in canoes, spears, and homes; it was also the premier material used in temples, offering platforms, and oracle towers. When an ohia tree was removed from the forest for carving into an idol of the warrior god, Ku, tradition demanded a human sacrifice. 鈥淚t鈥檚 a fundamental part of the intellectual foundation for Hawaii,鈥� says Gon. 鈥淵ou can tell the whole history of Hawaii with ohia,鈥� Hughes adds.

In 2012, diseased ohia covered about 2,300 acres in Puna. By 2014, dead ohia littered more than 15,000 acres of pristine rainforest. The disease was marching across the island of Hawaii, uncontained. Terrified the scourge would spread to other islands, the state government formed task forces and funded studies.

And yet, the disease remained a mystery. The very basics鈥攖he mechanism that causes the affliction鈥攚ere unknown. Was it caused by volcanic activity? Seismic damage to roots? No one knew. It was maddening, Hughes said. 鈥淭he trees that get hit by this become the breeding ground鈥攖hey become the vectors. They sustain the disease so it can kill other trees around it. It鈥檚 really diabolical. It鈥檚 a lot like other pathogens that impact humans,”聽Hughes聽says.聽鈥淚 refer to it as 鈥榯ree Ebola鈥� in talks if I really want to get people鈥檚 attention.鈥�

For 70 million years, Hawaii existed in relative isolation. The plants and species that slowly arrived on this collection of volcanic rocks in the middle of the Pacific hitched rides on traveling birds or floated in on the waves. Over millennia, they evolved into completely unique species, unseen anywhere else on earth. The list of Darwinian creations on the islands includes the ohia tree.

It鈥檚 not surprising, then, that the arrival of man irrevocably聽altered this tropical Eden. We introduced deer that trampled through the undergrowth; pigs that ate ground-nesting birds; weeds that choked out native plants; fire ants that roam the beach. The ecological history of Hawaii, especially in today鈥檚 globalized world, is a story of continual invasion.

鈥淲e鈥檙e the invasive species capital of the world, I鈥檓 sure,鈥� Hughes says, laughing. The cause of the disease, it seemed safe to assume, was another invader from beyond the breakers, imported by us. But still no one was sure just where it came from or how it got there.

By 2014, ecologists at the Forest Service and University of Hawaii tropical forest extension in Hilo聽knew they needed help, says J.B.聽Friday, an extension forester with the University of Hawaii College of Tropical Agriculture and Human Resources. Lisa Keith, a plant pathologist with the , got the call from a researcher at the university聽who had found fungi in samples of dead ohia. Could she take a look? 鈥淲e needed to learn as much as we could as fast as we could,鈥� she says. She began by taking the samples and performing 鈥渢ree autopsies.鈥� The inside of the ohia were discolored and showed signs of infection. The killer, it appeared, was clogging the tree鈥檚 vascular system, shutting off its聽water supply.

鈥淭here was a lot of stuff growing鈥� inside the trees, Keith says, 鈥渂ut we鈥檇 constantly find Ceratocystis fimbriata.鈥� A strain of C. fimbriata, a fungus and plant pathogen, was introduced to Hawaii聽decades ago, but records showed it had No one had ever seen the fungus do something like this to ohia.

Keith introduced pure cultures of the fungus into healthy ohia seedlings and waited. For months, nothing happened. Then one day a symptom appeared鈥攂rowning leaves, discolored bark鈥攁nd within one to two weeks the plant was dead. The fungus was likely a new strain of C. fimbriata, Keith and researchers realized, never before seen in the wild. It turned out the fungus could incubate inside trees for years (two to five for mature ohia), reproducing and slowly colonizing the聽ohia. 鈥淭he tree can survive for a while鈥攗ntil it鈥檚 finally had enough,鈥� Keith says.

The聽finding聽was dramatic: it鈥檚 exceedingly rare to discover a fungal strain attacking a new species (or 鈥渘ovel pathogenicity,鈥� to the scientists involved),聽let alone to make the discovery in just a matter of months. As for the disease鈥檚 origin, no one could be sure, but experts assumed the fungus hadn鈥檛 originated in Hawaii.聽Keith and her cohort called the plague but Hawaiians came to know it by a different name: Rapid Ohia Death.

Finally聽the disease had a name and officials had some inkling of what they were dealing with. State agricultural and forest employees quickly alerted the public and, in the summer of 2015, they to prevent to the spread of Rapid Ohia Death, or ROD, from the Big Island .

鈥淥hia trees cover more than one million acres statewide and ohia is widely considered the most important forest tree in Hawaii,鈥� Suzanne Case, the head of the state鈥檚 Department of Land and Natural Resources, . 鈥淭hey are so important for protecting our forest watersheds that it鈥檚 necessary our approach to combating this disease involves the highest levels of government and include non-government agencies.鈥�

The fungi spreads like a virus, so transporting infected ohia wood to a new area could spell disaster. (In quarantine inspections of ohia wood leaving the island, Hughes says, about 60 percent is infected with ROD.) It is so tenacious, Keith and officials believe, the fungus can be transmitted through dirty tools, like chainsaws, and even woodland creatures or the wind, since the microscopic fungal spores need only a small wound to enter new trees.

If nothing else, Keith鈥檚 studies showed how aggressive the fungus was. The question became not How do we cure ROD?聽Keith says, but 鈥淗ow can you slow its spread? How can you manage something like this on a large scale?鈥�

Greg Asner聽is up in the air every morning by 7 a.m. hunting for ROD. The skies are clearest early, he says. A Carnegie Institute for Science researcher and Stanford professor, is in high demand around the world. Last year, Asner used laser-guided imaging spectroscopy to in California鈥檚 drought-starved forests.

In Hawaii, where he鈥檚 lived for over 30 years, Asner 聽through the sky. He retrofitted a hulking twin turboprop Dornier Do 228鈥攁 utility plane with enough room for 28 passengers鈥攁nd packed its fuselage with high-tech imaging equipment to take the vital signs of foliage below. The silver and green 鈥淐arnegie Airborne Observatory鈥� can identify trees under 鈥減hysiological stress,鈥� i.e. starved for water and potentially suffering early stages of ROD. Until Asner took up the case in January, all the surveys of ohia on the Big Island had been distinctly low-tech鈥攅cologists either looked for browned trees in a helicopter or聽trudging through thick forests, looking for dying trees.

The view from 6,000 feet has not been good.

The extent of the disease is 鈥渨orse than people think, even worse than Flint [Hughes] knows鈥攁nd Flint knows better than anyone,” Asner says.聽鈥淚鈥檝e worked on invasive species for 20 years,聽and I鈥檝e just never seen anything this virulent.鈥�

But Asner, in his flying laboratory, isn鈥檛 just counting the dead. He is mapping out where trees are surviving the fungus. It鈥檚 part of a nascent, last-ditch plan from Keith,聽Hughes, Friday, and their respective departments to help the trees save themselves. It鈥檚 an idea, Asner says, that he can鈥檛 get out of his head: 鈥淲e go out there, find the survivors, direct Flint鈥檚 field team to go collect seeds, then get Lisa [Keith] in there to find out physiologically why there might be resistance in there.鈥�

鈥淛ust like when the Bubonic plague was going through Europe and people were dying by the millions, there were those that pulled through,鈥� the Nature Conservancy鈥檚 Gon says. 鈥淭hey were the progenitors of the population after.鈥� University of Hawaii conservationists are already for a seed bank,聽in preparation for the tree鈥檚 potential extinction.

The plan to find the survivors won鈥檛 take effect until summer, at the earliest. Until then, Hughes and the teams of scientists working on ROD have their work cut out for them. In January, officials confirmed the disease had spread to 聽and near聽, home of the Ironman championships. If the disease continues unabated, it will redraw the landscape of Volcanoes National Park and beyond.

鈥淲orst case scenario is that it spreads statewide and it decimates all of our ohia forests,鈥� Robert Hauff, forest health coordinator at the state Department of Land and Natural Resources, told reporters in December. 鈥淚t's a pretty bleak picture.鈥�

There have been some successes, though. The fungus has so far been contained to the Big Island, which seems to experts like a minor miracle, and a public awareness campaign has residents chipping in to prevent the spread and protect one of the island鈥檚 most storied trees.

In the beautiful grove of ohia trees where Hughes first realized the severity of the disease four years ago, ROD has taken its toll. The Kamehameha Schools, which owns the forest, understood the importance of the ohia, Hughes says. Before the outbreak, the schools'聽land manager was working to protect the forest from another invader. 鈥淭hey were in the process of putting in a very expensive feral ungulate-proof fence around the entire parcel鈥� to keep wild boar and other non-native hooved animals from wrecking the ecosystem, Hughes says. Today, the state-of-the-art fence stands around an area decimated by ROD, protecting nothing.聽

After the mechanism of ROD was finally unraveled, the Kamehameha land manager was devastated. “He just about broke down in tears,” Hughes says.聽Had his fencing spread the fungus? Was he to blame? The Forest Service veteran聽did his best to assuage the land manager鈥檚 guilt. The disease was completely absent聽four years ago, he said. No one could have known.

Last month, in hunting for the source of the fungus, Keith and her colleagues identified what they think may be its聽origin in Hawaii. The pathologists have found strains of the deadly fungus in a South American聽species of ornamental vine鈥攖he kind you'd install in your garden to give it that “tropical” feel鈥攊mported and聽sold in nurseries on the Big Island. It's just another plant humans have brought to the Aloha State, Hughes says.聽鈥淲e鈥檝e been playing Russian Roulette with our ecosystem for decades, if not centuries,鈥� he says.

鈥淚n terms of blame,” Hughes says, “we are to blame, unfortunately.鈥�

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