Pushing back flaps of yellowing banana leaves, Moisés Pulido trudges through a layer of dusty soil covering his plantation on the coast of La Palma. Under the blinding sun, batches of bananas are just about visible under the treetops, nestled together in lime-green bunches.
In late 2021, when the Cumbre Vieja volcano erupted on the western edge of this island in the Atlantic Ocean, burying 300 hectares (about 740 acres) of banana trees in ash and destroying 200 more, farmers like Mr. Pulido couldn’t imagine the volcano was doing them any favors.
But the Cumbre Vieja eruption could actually hold some of the answers to keeping bananas viable in the future, not just here but elsewhere.
Why We Wrote This
Cavendish bananas, the world’s most popular type, are under threat from a fungus that has wiped out other varieties. But the island of Tenerife may have just the conditions to protect them.
A fungus behind the condition known as Fusarium wilt – or Panama disease – is threatening bananas around the world. Some say the fungus, which blocks the flow of water and nutrients to the plant through its roots, could cause the popular Cavendish banana to go extinct.
But unlike in tropical areas such as parts of India and China, where most of the world’s bananas are produced, the subtropical climate of the Canary Islands – and La Palma’s western coast, in particular – has provided a path of resistance to the wilt.
Indeed, the volcanic ash that farmers once lamented after Cumbre Vieja’s eruption contains vital nutrients that protect the plant – and could be a key to bananas’ survival.
“Tropical crops, such as bananas, grow more slowly and are less productive [here] than in tropical places,” says Antonio Marrero, associate professor of agricultural and environmental engineering at the University of La Laguna in San Cristóbal de La Laguna, Spain. “But, in exchange, many of the diseases of tropical places are absent in the Canary Islands.”
The volcano’s gift
This is not the first time banana farming has been under existential threat from Panama disease. In the 1950s, banana wilt swept through plantations of the then-dominant Gros Michel banana, driving the variety nearly to extinction.
The market soon turned to the Cavendish banana due to its resistance to the wilt. But new variants of the fungus have emerged, some just as potentially threatening to the Cavendish as the original wilt was to the Gros Michel. Though the fungus has been found in some high-altitude, humid areas of the Canary Islands, that variant is not the most damaging type.
When farmers find wilt, they use commonsense measures, such as scooping out infested soil. But post-volcano, on what farmers like Mr. Pulido call “virgin soil,” it would be hard for the fungus to survive.
“Every time there’s a lava flow, time resets to zero,” says Jesús S. Notario del Pino, a professor of soil science and geology at the University of La Laguna. The life of the banana plants “starts again.”
Part of that logic is obvious. But the fungus is able to live for 20 years under the soil. And most of the world’s bananas – La Palma’s included – are monocrops. This means they are farmed on massive, dedicated plantations that grow nothing else. And all the bananas are genetic copies of each other, which makes them easy to produce but vulnerable to pathogens. When the wilt arrives, it can spread viciously.
Not only do volcanic eruptions kill the fungus, but volcanic ash from the Cumbre Vieja eruption also replenished the soil with nutrients like iron and zinc, and reduced the incidence of banana wilt, according to Dr. Marrero. Volcanic soil is also rich in potassium, which bananas rely heavily on to grow.
However like most other crops, bananas cannot be grown directly on volcanic soil. It takes decades for the weathering process to break down hardened lava into fertile earth. Instead, local farmers have to crush the lava finely and use it as a substrate before pouring fresh organic matter from other areas over the top – a practice they have been doing for over a century.
“Otherwise,” says Mr. Notario del Pino, “they just have to wait.”
The risks of monocropping
Farmers like Fran Garlaz say that even with the Canary Islands’ resistant soil and climate, the potential risks that come with monocropping are bigger than any one disease.
At Ecofinca Platanológico, an organic farm in the coastal town of Puerto Naos, Mr. Garlaz teaches visitors about the benefits of biodiversity. At one end of the site, he grows bananas. The other, a miniature jungle of hanging vines and lush plant life, is dedicated to experimentation. Around 200 crops grow here.
“Biodiversity is fundamental,” says Mr. Garlaz, pulling a foot-long knife from a case at his hip and taking a quarter-sized clipping from the base of a banana tree. Once banana trees bear fruit, they die. By planting the clipping next to an existing tree, a new one will grow, he says. “Monocropping is not logical or sustainable.”
But Mr. Garlaz is an outlier. Despite the efforts of small-scale farmers to diversify crops, almost half of La Palma is covered in banana plantations.
Still, even if the Cumbre Vieja volcano wiped out nearly 40% of La Palma’s banana production and the threat of the wilt is never out of view, farmers here say monocropping isn’t a point of discussion. On La Palma, banana farming provides 10,000 jobs for the island’s 85,000 residents. Since the volcanic eruption, most farmers here are just trying to get back on their feet.
Mr. Pulido says he always planned to rebuild the farm he lost in 2021. In the coming days, workers from his local cooperative plan to cut down the first batch of bananas that has grown since Cumbre Vieja destroyed his farm. He says neither volcano nor fungus will get in his way.
“I never thought about stopping,” says Mr. Pulido. “This is for our children, but also in honor of our parents and grandparents. It’s a matter of personal pride.”
