“I got the text and my stomach dropped,” recalls Shriner, who farms with her extended family and serves as president of the Kona Coffee Farmers Association. Like most of her peers, Shriner had been trying to mentally prepare for the moment for a long time. “We’d hoped we would have a few more years,” she says. “But when I learned it was here, I knew we had a massive challenge ahead of us.”

Coffee leaf rust, or Hemileia vastatrix, was first identified in Sri Lanka in the 1860s and has made its way through most of the world’s coffee-growing nations since then. The fungus, which thrives in warm, wet conditions and travels on the wind, debilitates and destroys coffee trees. It’s also one of the biggest factors most scientists point to when they say that climate change is coming for your morning cup of coffee.

Until this fall, Hawaii was one of the last coffee-growing regions in the world still untouched by rust. After the news broke, Shriner and other farmers, whose century-old operations spider out along a set of “upcountry” mountain roads, started to worry. They began turning over the waxy green leaves on their coffee trees, scanning for transparent dots and splotchy circles of orange spores. And, within weeks, they found them.

Coffee has been central to Hawaii’s agricultural economy since the 19th century; the bulk of the beans are grown in Kona, where a unique variety of tree (Kona Typica) along with the volcanic soil and mild temperatures combine to create a $50 million industry and a unique flavor profile that fetches upward of $60 a pound.

Now, in a state already hard hit by the impacts of climate change, farmers, scientists, and lawmakers are scrambling to prepare for the onset of rust. And although no one can predict just how much damage the fungus will do, its arrival could result in loss of production, changes to the flavor of the coffee, and a rise in prices for consumers.

Because addressing coffee leaf rust can be an expensive endeavor, experts also worry that many of Hawaii’s roughly 800 small-scale producers—whose mostly family-scale operations average around five acres in size—could exit the business. And for those farming organically, the odds look even worse.

“It’s really going to change everything we know about coffee in Hawaii,” says Shriner.

How an Invasive Beetle Set the Stage

“It was a big learning curve,” says Shriner of her own farm. “But after five or six years, we were able to manage it pretty effectively.”

A rust-infected coffee plant. (Photo credit: Andrea Kawabata)

Robert Barnes, who runs Kona Rainforest Coffee, a large organic coffee farm in Kona, said that, like many growers, he lost a great deal of his crop to CBB at first, but in recent years it has been a catalyst, prompting him focus in on the health of his trees and the soil in new ways.

“The first year was the worst. Now, we’ve been down to about a 1 percent loss, but the trees are super healthy,” said Barnes.

In 2015, Andrea Kawabata, an extension agent with the University of Hawaii College of Tropical Agriculture and Human Resources, took a trip to Brazil to learn about CBB. While there, she heard from growers who had also been struggling with coffee leaf rust, and brought home information, videos and photographs. Now, six years later, she’s using what she learned to hit the ground running as she’s been helping the farmers in Kona identify rust on their farms.

Time is of the essence, as Kawabata and other scientists are racing to respond and help farmers prepare for what’s ahead.

If farmers find rust on their farms before it’s on more than 5 percent of the tree’s leaves, farmers seem to be having some success spraying preventative fungicides made with copper and bacillus, a bacterium found in soil. But, Kawabata adds, “if coffee leaf rust incidence is past the 5 percent threshold, the disease seems to progress quite quickly, even with spraying.”

The cost of managing coffee rust on top of CBB will likely get passed along to consumers—creating a less predictable flavor for a higher cost. “All that additional labor is going to have to come out somewhere,” Shriner told me.

Melissa Johnson, a research biologist with the U.S. Department of Agriculture (USDA)’s Daniel Inouye Pacific Basin Agricultural Research Center (PBARC) has also been visiting farms and surveying the quick progression of the disease in Kona since December 2020.

“We found it all the way up and down the coast,” says Johnson. By January, she had surveyed 25 coffee lots—and 65 percent of those had coffee leaf rust on about 5 percent of their leaves. In February, the average rate of infection had jumped to nearly 10 percent and some trees had started to lose their leaves.

Farmers have started spraying a range of fungicides, but Johnson says, it’s reducing the “spores on the surface, but it’s not killing the infection inside the leaves.”

While the response to rust has been much faster than it was for CBB, Johnson says the speed at which the disease progressing is concerning. “We don’t know how much time growers are going to have before they start losing production.”

And then there are patches of what scientists are calling “feral coffee”—acreage that was no longer deemed worth maintaining after CBB hit. For Johnson, the most startling images of the progression of rust in Kona has come from one patch of feral coffee that she has been watching since December. What started out as an orchard full of green trees with a few yellow spots has progressed to become a solid yellow orchard. The trees are on a heavily trafficked patch of road and the spores may be spreading to other farms via passing cars, she says.

The Role of a Changing Climate

“The typica variety, which is well-known as the face of Kona coffee, is one of the most susceptible varieties there is,” says Keith. The scientist and her colleagues are working with researchers in Portugal to determine the physiological race of the rust—from among more than 50 existing races—that has landed in Hawaii.

When I spoke with Keith in February, she said most farmers were managing the disease because the weather was still relatively cool. “It’s in the latent phase and it has the potential to build up,” she said.

Coffee leaf rust grows well in wet, warm, and humid climates. It thrives at temperatures that are between 70 to 77 degrees Fahrenheit, says Keith, and that range is more and more common up in the cooler mountainous regions of Hawaii as the climate shifts.

“You’re finding it at elevations that would have been too cool in the past. And that’s not just coffee leaf rust. Unfortunately, that’s what is being seen with a lot of pathogens and pests; they’re moving into areas where they weren’t observed previously, as temperatures are changing,” said Keith.

Lawmakers on the island declared a state of climate emergency in 2019 and are currently drafting a climate action plan. According to the National Oceanic and Atmospheric Administration (NOAA), average annual temperatures increased 2 degrees since 1950 and while they have leveled off in recent years, “historically unprecedented warming” is projected by the end of the 21st century. Extreme rainfall events have also become more common on the island of Hawaii, and 2020 was an exceptionally wet year for most Kona farms.

Lessons from Latin America

Ballar remembers seeing his extended family grapple with the impacts of rust at his grandmother’s kitchen table as a child, and being tasked with going out into the fields to find coffee leaves infected with rust—called La Roya in Spanish—to bring back to their parents. At first, it was a competitive hunt that took skills, but it quickly became easier.

Arturo Ballar (right), with a Kona coffee farmer. (Photo credit: Arturo Ballar)

“In the very early stages, you can’t see any damage,” he remembers. The leaves looked green, but when held to the light they were covered with transparent dots.

In Costa Rica, he says, the disease typically had three phases: it would start somewhat dormant in the cool season. Then, when warmer temperatures arrived, the leaves on the trees would turn from green to yellow. Finally, many trees would lose their leaves and coffee beans. When this happened, it typically took at least two years for the trees to be productive again—and that was only if farmers had put time and attention into controlling rust with fungicides and keeping their soil healthy.

Farmers who made it through that initial window of production loss adjusted to the new reality, and soon plant breeders developed varieties of coffee that were resistant to rust, which helped them maintain somewhat productive orchards.

Then came 2012. “In Central America, Mexico, and South America, we saw a very, very severe case of rust. It was very aggressive,” recalls Ballar. That year, none of the coffee-producing nations were spared, but some had it especially bad. Nearly 70 percent of the coffee acres in Guatemala were impacted by rust, for instance. In El Salvador it was almost 74 percent of the land.

“They had massive tree deaths and loss of yield throughout the entire Central American region. It created a huge humanitarian crisis for those farmers and was partly responsible for why we had a wave of immigration: Farmers had to leave their farms,” says Shriner.

Since then, Ballar says some Costa Rican farmers have been able to get a handle on the disease, but many have lost crops, money, and ultimately their farms. “It’s like Charles Darwin said, they had to adapt or disappear,” he says. “And that’s what it’s going to happen in Kona.”

As Ballar works to help farmers prepare for the months ahead, he’s stressing the role of “prevention over cure” and encouraging farmers to get their soils tested so they can help their trees can stand up to the rust in the coming years.

And while some farmers will take that route, others are awaiting permission to begin using a new, more powerful fungicide. Currently there are no systemic fungicides labeled for use on coffee in the U.S., and the Hawaii Department of Agriculture is moving fast to try to get one—called Priaxor—approved through an emergency exemption from the Environmental Protection Agency. State lawmakers have also advanced a bill that would subsidize its use for coffee farmers.

The systemic fungicide—which can be taken up into plant tissues and kill fungal matter from the inside—is already approved in the U.S. for use on corn, soybeans, cotton, potatoes, and other crops.

And while it would give farmers a much stronger tool to fight the rust, it could also have significant environmental impacts on the local ecosystem. Pyraclostrobin, the key ingredient in Priaxor, has been shown to have adverse effects on aquatic ecosystems. One study found that it was among several fungicides that pose a high risk to amphibians such as frogs and toads, for instance.

Importing rust-resistant coffee varieties from Latin America is another option many farmers are exploring, but new resistant varietals likely won’t have the same flavor as the Kona Typica—and that worries growers and others hoping to maintain the Kona coffee brand moving forward. There’s also a one-year quarantine period required for new trees. “A lot of growers may not have a year before they start losing production,” says Johnson.

The Challenges for Organic Growers

Now, like other organic farmers in Kona, the couple is concerned that organic treatments won’t be enough to fight off rust once the temperature rises this spring. So, they’re up against a difficult decision: use Priaxor or run the risk of losing their trees.

“We could do nothing and hope for the best, but that would be a real crapshoot,” he says, comparing the decision to treating cancer with chemotherapy. “If the chemicals are the only way to save your life, you might have to do it.”

In mid-February, the Hawaii Department of Agriculture declared a state of emergency that would allow organic producers to use the systemic fungicide without losing their certification—if the decision is approved by their certifier. They wouldn’t be able to sell that year’s crop as organic, but they wouldn’t have to go through three years of transition if they stopped using it either.

The week I spoke with Robert, he described Dawn sitting in their orchard, crying about the impending impact on the trees they’ve been nurturing for years. “They’re like her babies. She gets really emotional about it. And I don’t know how our customers are going to take it because they love the [fact that we’re] organic,” he says.

Melissa Johnson doesn’t know whether or not organic coffee farms will be able to maintain their certification in the coming years. She studied eight farmers in Kona as they dealt with CBB and two were certified organic. “Both the organic ones have moved to conventional just because it was really hard. So, I expect we might see more drop in organic producers again. Hopefully it will be temporary,” she said.

Plant pathologist Lisa Keith is optimistic that organic farmers will eventually have options for treating rust, even if the timeline for that happening is still unpredictable. “We found that on certain farms, there are [fungi] that seem to love to feed on [coffee rust] spores. So, we’re going to try to identify them,” she said. She also plans to look into the potential for solutions that utilize “essential oils and other environmentally-friendly products that would be approved for use in certified-organic production.” Pruning techniques and managing airflow between the trees to reduce moisture may also help, says Keith.

Green coffee beans growing in Kona. (Photo credit: Arturo Ballar)

But it’s not just organic farmers who are at risk of dropping out of the industry.

Johnson says she’s concerned for all small-scale farmers, who are already facing mounting labor and input costs and are afraid of the unknown. “It’s really stressful, and understandably so. I think a lot of them feel kind of helpless,” she says.

UH’s Andrea Kawabata is talking with a number of farmers who are exploring alternative crops and talking about exiting farming. “I haven’t heard of any farmers completely giving up yet. But, that could be next,” she said. Kawabata points to the fact that the median age of farmers in Hawaii was 60 in 2017 (the last year the USDA conducted an ag census), and many older farmers don’t have family members in place to take over the farm.

A mainland-owned corporation moved in and set up a very large farm a few years back and many of the existing independent farms are already working with large management companies that oversee the labor on 20 to 50 farms at a time. Together, these shifts represent a big step away from the smallholder model that put Kona on the map, says Suzanne Shriner. “[Under the management companies], the farmer essentially does nothing. He just turns over the land to them. So, we’re losing some of that individuality that our farms had for years,” she says

Keith stresses that what’s on the line is more than a really good cup of coffee. “It’s people’s livelihoods,” she says. “It’s about the community and about helping the families and working together to try to make the best out of this unfortunate situation.” If there’s a bright spot, she adds, it’s the fact that the scientific community and the coffee industry are collaborating so well to address rust head-on.

Because he’s seen many farmers in Costa Rica bounce back over the last decade, Arturo Ballar is also keeping his eye on the silver lining—even if it requires a kind of stubborn patience that is increasingly familiar to many of us in 2021.

“It’s going to have a very positive impact—in the long run,” he says. “Production will probably be affected quite a lot in the next few years and many farmers won’t adapt. So, this is going to be a long journey, and the structure of the industry could be changed completely.” But in the end, Ballar adds, “There will be opportunity for farmers who are willing to adapt.”