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Devastating Banana Fungus Arrives In Colombia, Threatening The Fruit's Future

Aug 16, 2019
Originally published on August 16, 2019 10:57 pm

One of the biggest fears of the fresh fruit industry just came true.

A fungal disease that has been destroying banana plantations in Asia has arrived in Latin America.

"For me, the worst moment was [seeing] the first pictures," says Fernando Alexander García-Bastidas, a banana researcher at the Dutch company Keygene, who carried out tests confirming what had happened.

Some farmers in Colombia, where García-Bastidas grew up, sent him photos of their banana plants two months ago. The plants were turning yellow and wilting, as if they didn't have water.

García-Bastidas recognized the symptoms. He'd seen them before, in devastated banana plantations in the Philippines. These are the effects of a fungus called Fusarium. But the implications were devastating, and García-Bastidas hoped he was wrong.

"I felt this thing in my heart that was like kind of praying for a false positive, or something like that," García-Bastidas recalls. "It was terrible" — and doubly distressing because it affected his homeland.

For the next month, he says, he had trouble sleeping. He flew to Colombia, collected samples of the wilting plants and tested them. The results confirmed his fears. The plants were infected with a variant of Fusarium fungus called Tropical Race 4, or TR4.

TR4 began marching through the world's banana-growing countries in the 1990s. First detected in Taiwan, it moved to Malaysia and Indonesia, then jumped to China, Australia and the Philippines. It showed up in Mozambique, in Africa, five years ago.

People involved in banana production or research have taken extreme measures to prevent it from spreading. When García-Bastidas visits an area where the fungus is present, he'll buy a new pair of shoes before entering another banana-growing region to avoid bringing in a speck of fungus-contaminated soil. The main international conference on banana research no longer takes place in any banana-growing country, to reduce the risk that the fungus might hitch a ride with one of the researchers.

Somehow, though, it has now hopped the ocean and arrived in Latin America. García-Bastidas says he expected it would happen someday, but not so quickly. "It's very difficult to control the spread of this disease," he says.

The Fusarium fungus lives in the soil. No one knows how to eradicate it or to treat infected plants. It invades banana plants through their roots and then blocks the vessels that carry water and nutrients, starving the plants. It kills most members of the banana family, including the variety called Cavendish that accounts for the vast majority of bananas traded internationally.

Colombian authorities have declared a national emergency and launched efforts to contain the fungus. Banana growers are destroying all banana plants anywhere near a plant that shows symptoms.

They may be too late, though. By the time symptoms appear, the fungus has already been present in the soil around that plant for at least a year. During that time, people may have been walking through the farms, perhaps picking up bits of fungus on their shoes and spreading it. "I hope I'm wrong, but most likely it spread already to other places," says García-Bastidas.

The only good news may be that the disaster will unfold slowly. It can take years or decades for the fungus to move across entire countries or continents. In Asia, individual farms have been devastated, but many of the affected countries remain major banana producers.

Meanwhile, researchers are trying desperately to find a new kind of banana that can survive Tropical Race 4.

Scientists in Australia have created a fungus-resistant variety using genetic engineering. It's still being tested and would require government approval before it could be grown or sold.

Other scientists are looking through nature's storehouse. When García-Bastidas was a graduate student at Wageningen University, in the Netherlands, he tested 300 different members of the banana family.

"Unfortunately, 80% of the [varieties] that I tested were susceptible to TR4," he says. "But there is a little bit of hope with the other ones that were not susceptible."

None of those fungus-resistant plants are ready to replace the bananas that currently fill supermarket shelves. Most of them are cooking bananas, or plantains. Others are wild bananas with tiny fruit that's inedible; the pods are full of seeds.

The hope, however, is that plant breeders can take these plants and cross-pollinate them, mating them with other, more commercially viable bananas, reshuffling the genes to create new varieties that are both delicious and immune to TR4. The company where García-Bastidas now works, Keygene, is one of the research centers pursuing this goal.

Breeding bananas is so complicated that few people have ever tried it. For one thing, it takes bananas with seed-filled fruit, since those seeds represent the new genetic combinations that plant breeders want. Yet those seeds can't appear in the fruit of a commercial variety.

García-Bastidas says the task is very difficult. But it is possible. And now it's necessary.

Copyright 2019 NPR. To see more, visit https://www.npr.org.

AILSA CHANG, HOST:

If you like bananas, we've got some bad news. A fungus that kills the ubiquitous fruit has appeared for the first time in Latin America, which is the source of most bananas sold in the U.S. This disease has caused huge problems in Asia, and there is no cure for it. NPR's Dan Charles has the story.

DAN CHARLES, BYLINE: This is what Fernando Garcia-Bastidas has been dreading, hoping it wouldn't happen - and then, one day in June, it did.

FERNANDO GARCIA-BASTIDAS: For me, the worst moment was the first pictures, of course.

CHARLES: Some farmers in Colombia, where he grew up, sent him pictures of some of their banana plants. They wanted his opinion because Garcia-Bastidas is an expert on bananas. He works for the company Keygene in the Netherlands. In the photos, the plants were wilting as if they didn't have water. Their leaves were turning yellow. Garcia-Bastidas knew right away these were the symptoms of a fungus called Fusarium.

GARCIA-BASTIDAS: I felt this thing in my heart that it was like kind of praying for a false positive or something like that. It was terrible.

CHARLES: For the next month, he says, he couldn't sleep. He flew to Colombia, tested samples of the wilting plants and confirmed his fears. It was a deadly form of Fusarium fungus called Tropical Race 4, or TR4. TR4 began marching through the world's banana-growing countries in the 1990s - Malaysia, Indonesia, China, Australia, the Philippines. It showed up in Mozambique, in Africa, five years ago. And now, somehow, it's hopped across the ocean to Latin America.

GARCIA-BASTIDAS: It is very difficult to control the spreading of this disease.

CHARLES: If this fungus gets into a plantation, does that mean that the plantation eventually is doomed?

GARCIA-BASTIDAS: Yes.

CHARLES: The fungus lives in the soil. No one knows how to eradicate it or protect plants from it. Banana growers just try to keep it from spreading. In Colombia, they're now destroying hundreds of acres of banana plants, anything close to the infected ones. The problem is by the time symptoms show up, the fungus has already been there for a year. And all that time, people may have been walking across the ground, picking up bits of fungus on their shoes.

GARCIA-BASTIDAS: I hope I'm wrong, but most likely it spread already to other places.

CHARLES: The only good news, really, is that it's a slow-moving disaster. In the Philippines, for instance, the fungus has been destroying individual farms for a decade now, but the country is still a major banana producer. And in the meantime, scientists are searching for a new kind of banana that can survive TR4.

Researchers in Australia have created one with genetic engineering, but growing it commercially or selling it will take approval from governments. Others are looking for solutions in nature. When Fernando Garcia-Bastidas was in graduate school, he checked 300 different kinds of bananas to see if they could resist TR4.

GARCIA-BASTIDAS: And, unfortunately, 80% of the material that I tested was susceptible to TR4, but there is a little bit of hope with the other ones that were not susceptible.

CHARLES: These fungus-resistant plants are not about to replace the bananas in supermarkets. Most of them are cooking bananas or plantations or wild bananas with tiny fruit that you can't eat. They're full of seeds. But the hope is scientists can take those plants and improve them - cross-pollinating, reshuffling the genes to create new bananas that are still immune to TR4 but also delicious. Few people have ever tried this. Breeding bananas is very, very hard, but Garcia-Bastidas says it can be done.

Dan Charles, NPR News. Transcript provided by NPR, Copyright NPR.