The air in the mountains of Nariño is thin and sweet. Standing on a steep hillside nearly 2,000 meters above sea level, you feel suspended between the deep green of the coffee trees and the vast, Andean sky. The unique microclimate here, a result of equatorial sunlight and cool mountain nights, allows coffee cherries to mature slowly, developing the stunningly complex and floral notes that make Nariño’s coffee so sought after.
I was visiting the farm of a producer named Elena, whose coffees I had admired for years. The purpose of these trips is always twofold: to taste and select the best lots, but more importantly, to listen. To understand the reality behind the beautiful product that ends up in our cups.
As we walked between rows of old Caturra trees, their branches heavy with maturing cherries, Elena stopped and gently turned over a leaf on a lower branch.
“Mire, Miguel,” she said, her voice quiet. “La roya.”
I leaned in. On the underside of the leaf were several small, powdery spots, the color of rust. To the untrained eye, they would look insignificant. To a coffee farmer, they are a siren, a warning of a devastating threat.
“It always starts here,” she explained, rubbing the orange dust between her thumb and forefinger. “In the shadows, where the leaves stay wet after the rain. From here, if you are not careful, the wind carries it like a fire. It takes the leaves, and a tree without leaves cannot feed its fruit. It cannot live.”
This is the conversation that happens on coffee farms all over the world. It’s a quiet, constant battle against an enemy that has shaped the history of coffee itself.
What Elena calls la roya is known to scientists as Hemileia vastatrix. The name itself tells the story: Hemileia refers to the half-smooth nature of its spores, and vastatrix is Latin for “devastator.” It is a fungus that has lived up to its name since it was first identified in the 1860s.
Historically, its impact has been catastrophic. In the late 19th century, it completely wiped out the flourishing coffee industry in Sri Lanka (then Ceylon), forcing the British to pivot to planting tea, which is why the island is now synonymous with tea production. This single event demonstrates the fungus’s power to reshape economies and cultures.
The fungus works by landing on a leaf and, in the right conditions of warmth and moisture, growing a microscopic tube that penetrates the leaf’s surface. Once inside, it hijacks the plant’s cells, draining them of nutrients and disrupting photosynthesis. The orange spots are the visible result—millions of new spores ready to be carried by the wind to the next leaf, the next tree, the next farm.
Making matters worse, a changing climate is giving the devastator an advantage. Warmer average temperatures are allowing the fungus to survive at higher and higher altitudes, threatening pristine coffee regions that were once considered safe havens. For a deep dive into the science, World Coffee Research has an excellent varietal catalog that explains the disease in great detail.
Elena and I continued walking, and she pointed to a section of the farm on an adjacent hill. The trees there were smaller, more uniform.
“That is Castillo,” she said. “It is a hybrid, resistant to the rust. It gives us security. The production is good, and I do not lose sleep worrying about the fungus. But,” she paused, looking back at the older Caturra trees around us, “the flavor… the Caturra has a spark. A sweetness. It is the coffee my father and his father planted here. To replace it feels like losing a part of our history.”
This is the impossible choice that farmers like Elena face. And it’s a dilemma rooted in genetics.
Many of the most celebrated heirloom Arabica varietals—Typica, Bourbon, Caturra, Geisha—are highly susceptible to leaf rust. The industry’s solution has been to create hybrids by cross-breeding Arabica with the more robust (but less nuanced in flavor) Robusta species, which carries natural resistance. Research centers like Cenicafé in Colombia have developed varieties like Castillo and Colombia precisely to protect farmers from la roya.
For decades, these hybrids had a stigma in the specialty coffee world, often seen as lacking the complexity of their heirloom parents. While that was once true, modern breeding programs are now producing disease-resistant coffees with exceptional flavor. However, the choice for the farmer remains incredibly difficult.
Renovating a single hectare of a farm can cost thousands of dollars and means a wait of three to four years before the new trees produce a full harvest. For a smallholder farmer, this is a monumental financial risk. Can they afford to sacrifice years of income for future security? Or do they take their chances with their cherished, more vulnerable trees, relying on constant monitoring and expensive, often organic-certified, copper-based fungicides to keep the disease at bay?
Standing there on that mountainside, I was reminded that the numbers on a coffee scoring sheet never tell the full story. That bright acidity and jasmine aroma in a Nariño Caturra doesn’t just come from the soil. It comes from Elena’s resilience, from her courage to cultivate a delicate plant against the constant threat of ruin.
It’s why the price we pay for a bag of coffee matters so much. That premium isn’t a luxury; it’s a direct investment in a farmer’s ability to manage these immense risks. It provides the stability needed to perhaps renovate a small section of their farm, to afford the proper organic inputs to protect their crop, or to simply absorb the loss of a few trees without facing financial collapse.
The next time you’re buying coffee, I encourage you to lean into the story. Ask your roaster about the varietal. Is it a classic heirloom or a modern, rust-resistant hybrid? Each has a story of risk, innovation, and survival. Every cup we drink is a testament to a farmer’s successful battle against the devastator, a battle fought every day in the quiet shade of the coffee mountains.
