Images by John Hook

When I first meet Lisa Keith, she’s wearing mismatched pink and purple socks. We’re inside her laboratory at the Daniel K. Inouye Pacific Basin Agricultural Research Center on the outskirts of Hilo. Besides the security badge I’m required to wear, it feels like a more cluttered version of my high school science lab. Every shelf is crammed with boxes of latex gloves and little bottles of colored liquid. The refrigerators read “Authorized Personnel Only.” It’s a Wednesday in late August 2016, and Keith, a slight woman with unruly brown hair and a smile that engulfs her narrow face, is explaining how she and her team uncovered the identity of one of Hawai‘i’s most notorious killers: the disease known as rapid ‘ōhi‘a death, which, in the past six years, has infected nearly 50,000 acres of Hawai‘i Islands’s native forest.

Keith is a plant pathologist, which means that she studies diseases in plants for a living. Like doctors and homicide detectives, in a world without death, plant pathologists wouldn’t exist. There are thousands, if not millions, of known plant pathogens in the world, and hundreds in Hawai‘i alone. Keith’s job is to identify those pathogens, which can take the form of viruses, fungi, bacteria, or nematodes, and learn as much about them as she can. Where do they live? How do they spread? How do they kill? In the case of this previously unknown strain of Ceratocystis fimbriata, the pathogenic fungus that affects the ‘ōhi‘a lehua tree, it prefers strangling. The fungus enters the tree through a wound—a broken limb, say—and spreads into the tree’s sapwood, the soft outer layer that conveys water from the tree’s roots to its leaves. It eventually cuts off the water supply entirely. Once that happens, the tree will be dead within weeks, hence the fungus’s nickname.

That the disease can spread and kill so quickly has alarmed scientists and residents alike. ‘Ōhi‘a is one of Hawai‘i’s most important native trees, featured in Hawaiian mo‘olelo and in cultural practices like hula, and a critical part of a complex ecosystem. The tree is one of only a few species that grows among the island’s lava fields; over time, the trees transform the barren terrain into a dense, wooded landscape thrumming with native birds and other wildlife. ‘Ōhi‘a forests, with their dense foliage and elaborate root systems, also help rainwater soak into the ground, recharging the island’s aquifer and preventing erosion that leads to flooding, brown water events, and the loss of coral.

Listening to people describe the early days of the epidemic, in 2010 and 2011, is like listening to the opening scenes of a zombie apocalypse movie. ‘Ōhi‘a began dying by the dozens, then the hundreds. No one knew what was killing them. All of the tests for known diseases came back negative. In 2014, Keith, who had moved to Hilo in 2002 to study agricultural diseases with the USDA’s Agricultural Research Service, was contacted by Brian Bushe, a faculty member at the University of Hawai‘i’s College of Tropical Agriculture and Human Resources. Bushe was trying to crack these mysterious ‘ōhi‘a deaths, and he had narrowed the list of suspects down to the genus Ceratocystis. “I remember getting the call,” Keith says. “[Brian] asked, ‘Would you be interested in helping take a look at this?’ That was a big turning point.”

It took several months and methods, including a molecular DNA test, for Keith and her team to identify Ceratocystis fimbriata. In 2015, the state enacted a quarantine to prevent the disease from spreading to neighbor islands, which, thus far, seems to have worked; to date, there have been no confirmed cases on other islands. On Hawai‘i Island, however, the disease has not flagged. In November 2016, the first confirmed case of rapid ‘ōhi‘a death was reported on the Hāmākua Coast, marking a worrisome northward expansion.

Despite the seriousness of the issue, Keith and her army of postdocs also seem to be having one hell of a time. The atmosphere in the lab is light and collegial. Keith herself is lively, not what you’d expect of your typical scientist. Her loud laugh is so full of mirth that it’s contagious—you can watch it spread, from Keith to her assistants, like one of her studied diseases hopping from tree to tree. During my visit, she discusses the need to swap out her photo on the rapid ‘ōhi‘a death website. It’s just too happy. “The picture is of death and destruction, and I’m pointing at it with a big smile and my coffee,” she says. “We have the two foresters looking awesome, and then there I am: ‘Dying seedlings!’” She mimes a touristy pose and flashes a big, toothy grin.

The positivity is, no doubt, simply a part of Keith’s personality, but a small portion of it also stems from what she describes as the thrill of the chase. “That can sound really demented,” she admits, “[because] it is devastating. But at the same time, applying all your knowledge and experience to help solve a major problem is exciting.” She compares the process to—what else?—Scooby-Doo. “We’re ripping the mask off a new invasive pathogen,” she says, “and maybe they would have gotten away with something far worse if we hadn’t solved the mystery.”

In the case of rapid ‘ōhi‘a death, however, the episode is far from over. This particular villain is still at large, which is why Keith and colleagues are working harder than ever. For someone used to toiling away behind the scenes, it has been disorienting to walk into her local KTA grocery store and see her name on posters warning residents not to transport ‘ōhi‘a wood. J.B. Friday, who, as an extension forester with the University of Hawai‘i received the first reports of dying ‘ōhi‘a, says the disease has meant a lot more nights and weekends, taking tree samples, and coordinating outreach. The work is nonstop.

Keith takes it in stride. After all, this isn’t television. “It’s not a happy, feel-good project,” she admits. “In plant pathology, it’s doom and gloom you’re working with, so you shouldn’t feel bad high-fiving when you do start answering questions.”