The pandemic that threatens to destroy the world's most popular fruit

This is not covid-19, the disease caused by the new coronavirus. Tropical Race 4 (TR4) affects bananas. Also known as Panama disease, it is caused by the fungus Fusarium oxysporum, which has been destroying banana farms for the past 30 years.

It would be just another disease affecting plants if it weren't for the fact that in the last decade the epidemic has suddenly accelerated, spreading from Asia to Australia, the Middle East, Africa and, more recently, Latin America, where most bananas sent to supermarkets in the Northern Hemisphere come from.

Panama disease is currently present in more than 20 countries, sparking fears of a "banana pandemic" and a shortage of the world's most consumed fruit.

Scientists around the world are working around the clock to try to find a solution, including creating genetically modified bananas (GM) and a vaccine.

'New normal'?

But, like covid-19, the question is not only whether we can find a cure, but also how we will live with a "new normal" that will change bananas forever?

The first place to look for clues is the origin of the modern banana that we all know. Your story shows exactly what happens if this disease is ignored.

It's not the first time bananas have faced a threat, explains Fernando García-Bastidas, a plant health researcher who studied TR4 at Wageningen University in the Netherlands before working at a Dutch plant genetics company trying to fight the disease.

In the 1950s, the industry was decimated by what it describes as "one of the worst botanical epidemics in history", when panama disease first occurred.

Origin

Fungal disease arose in Asia, where it evolved with bananas, before spreading to the vast plantations of Central America.

The reason it was so devastating, garcía-bastidas says, is the fact that bananas were all of just one variety, gros Michel or 'Big Mike'.

This species had been chosen for cultivation by producers because it produces large and tasty fruits that can be cut from the tree still green, allowing the transport of highly perishable exotic foods over long distances, while they continue to ripen.

Each plant was a clone of approximately the same size and shape, produced from lateral shoots that develop from the stem of the roots, facilitating mass production.

This means that each banana tree is genetically almost identical, producing fruits consistently, without unforeseen events. From a commercial point of view it was excellent, but from an epidemiological point of view, it was an outbreak waiting to happen.

The banana production system was weakly based on the limited genetic diversity of a variety, making them susceptible to disease, García-Bastidas says.

Lesson learned?

But it's wrong who thinks the industry has learned its lesson.

The search for a variety to replace Gros Michel that could be resistant to panama's disease was then started. In the 1960s, one species, Cavendish, called banana nanica in Brazil, showed signs of resistance that could save the banana industry.

Named after the 7th Duke of Devonshire, William Cavendish, for growing the plant in his greenhouse at his official residence, Chatsworth House, the banana could also be transported green — although it tasted softer than gros Michel.

Within a few decades, it has become the new benchmark for the banana industry and remains to this day. But for scientists who watched nervously the vast expanding plantations, it was only a matter of time before there was another outbreak.

In the 1990s a new strain of Panama disease, known as TR4, emerged, again in Asia, which was lethal to Cavendish bananas.

This time, with a globalized economy in which researchers, farmers and other visitors to banana plantations roam freely around the world, it has spread even more rapidly.

García-Bastidas, who completed his PhD in TR4 at Wageningen University, describes modern banana disease, which attacks the vascular system of plants by making them wither and die, as a "pandemic."

"Bananas are undeniably among the most important fruits in the world and are an important staple food for millions of people," he says. "We cannot underestimate the impact that the current TR4 pandemic can have on food security."

García-Bastidas was the first to see TR4 outside Asia in Jordan in 2013.

Since then he has "crossed his fingers" so that the disease does not affect developing countries, where bananas are a staple food.

But records of the disease have already been observed in Africa, particularly in Mozambique.

The reason TR4 is so deadly is because, like covid-19, it spreads through "stealth transmission", albeit on different time scales.

A sick plant will stay healthy for up to a year before showing the symptoms of the disease: yellow spots and withered leaves. In other words, when TR4 is identified, it is too late and it will have spread through spores in the soil in boots, plants, machines or animals.

García-Bastidas, who is originally from Colombia, knew that TR4 would reach the center of banana production in South America.

'Worst nightmare'

In 2019, his worst nightmare came true —the phone call came from a farm in Colombia. The banana trees had yellow and wilted leaves. And the producer wanted to send you samples.

"It was like a nightmare," he says. "One minute I'm on the farm, the next in the lab, the next explaining to the Colombian government minister that the worst has already happened. For a long time, I couldn't sleep well. It was heartbreaking," he recalls.

Like all other countries with TR4, Colombia is now trying to slow the outbreak as the world anxiously observes signs of the disease in the rest of Latin America and the Caribbean.

As there is no cure, all that can be done is to quarantine infected farms and apply biosecurity measures, such as disinfecting boots and preventing plant movement between farms. In other words, do the equivalent of washing your hands and maintaining social distancing.

At the same time, the race to find a solution is in full swing.

In Australia, scientists have developed a genetically modified Cavendish (GM) banana that is resistant to TR4. The Bill and Melinda Gates Foundation is also funding research in the area.

However, despite strong scientific evidence that genetically modified foods are safe, bananas are unlikely to be on the shelf of a supermarket near you as long as regulators and the public remain suspicious.

For García-Bastidas, who now works at the research firm KeyGene in collaboration with Wagegingen University in the Netherlands, transgenic bananas are an "easy solution" that can solve the industry dilemma for five to ten years, but not solve it altogether.

At the end of the day, he says, the biggest obstacle is having an entire industry based on a single cloned variety of other plants.

The tests are being developed only to track TR4, as bananas have suffered from receiving fewer research resources than other basic crops.

More diversity

Instead, García-Bastidas wants to introduce more diversity into banana culture, so that it is more resistant to outbreaks of diseases such as TR4. He points out that there are hundreds of bananas with potential for cultivation around the world. Why not use them?

In countries such as India, Indonesia and the Philippines, people eat dozens of different varieties of bananas, with different flavors, smells and sizes. But they are difficult to grow and export on the scale of cavendish, which was created to support transportation across the oceans.

In their laboratory in the Netherlands, García-Bastidas and his colleagues are using the latest DNA sequencing techniques to identify TR4-resistant genes and produce bananas that can support the disease and be commercially viable.

"We have hundreds of varieties of apples," he said. "Why not start offering different varieties of bananas?"

The best hope is for an export-resistant banana to emerge in the next five to 10 years. But that's not a silver bullet. After facing not one, but two pandemics in the last century, this time the banana industry will have to seek more than just introduce another clone to the market.

Dan Bebber, associate professor of ecology at the University of Exeter in the UK, has spent the last three years studying the challenges to the system to maintain the supply of bananas as part of a uk government-funded bananex project.

According to him, the best way for the banana industry to survive TR4 is to change the way this fruit is grown.

At the moment, Cavendish bananas are grown in a vast monoculture, which means that not only TR4, but all diseases spread rapidly. During the growing period, bananas can be sprayed with fungicides 40 to 80 times.

"This can have big impacts on the soil microbiota," Bebber says. "To take care of bananas, you have to take care of the soil."

Bebber points to reports from the Philippines that organic farms fared better against TR4 because the microbiota in the soil is able to fight infection.

He says banana farms should seek to add organic matter and perhaps deploy a crop rotation system to increase protection and fertility, using microbes and insects instead of chemicals as "agricultural pesticides," as well as leaving more free space on the ground to encourage wildlife.

This may mean an increase in the price of bananas, but in the long run they would be more sustainable.

According to Bebber, bananas are very cheap today. Not only because the environmental cost of a monoculture with heavy chemicals has not been taken into account, but mainly the social cost of employing people on very low wages.

The NGO Banana Link, which campaigns on the subject, blames supermarkets for forcing ever lower prices, compromising the environment, workers' health and, finally, the vitality of the banana crop.

Bananas produced for popular trade somehow ensure that farmers receive a fair price for them, but Bebber says workers across the industry are beginning to demand better wages.

Again, he says this feeds TR4, as they need to be paid fairly to ensure that farms are better managed for disease prevention.

"For years, we have failed to take into account the social and environmental cost of bananas," he says. "It's time to start paying a fair price, not just for the workers and the environment, but for the health of the bananas themselves."

Bananageddon

Jackie Turner, an American filmmaker who questions how bananas are grown since she worked on a plantation as a student, agrees that the solution lies in justice and diversity.

In her film Bananageddon (a combination of the words banana and armageddon), she talks to scientists trying to stop the spread of TR4, food safety experts who warn about shortages and plantation workers concerned about their livelihoods.

"TR4 is very similar to covid-19 because it has no treatment," she says. "It's a 'doomsday' scenario for bananas," he said.

After traveling the world for two years to observe the impact TR4 is already having, Turner is convinced that bananas need to be grown in a different way, which means introducing new varieties.

She says this will not only be better for the environment and for disease protection, but also for the consumer.

To try to encourage the public to support smallholder farmers who grow different varieties, she created The Banana List.

The compilation brings together stores that sell different varieties of bananas, so that consumers can try them out and a new demand arises.

For example, the red nanica, which has a flavor reminiscent of raspberries, the girl's finger, smaller and sweeter than Cavendish, or Blue Java, tasted like vanilla ice cream. Bananas are not only delicious, but will help create a diverse type of agriculture that is more resistant to disease.

For Turner, the banana pandemic can have positive results if it forces us to grow bananas more ecologically and eat a greater variety of fruits.

"Maybe we'll eat fewer bananas and pay more for them," he admits. "But we know they'll be better bananas."

This report is part of Follow the Food, a series that investigates how agriculture is responding to environmental challenges. Follow the Food outlines the emerging responses to these problems —high- and low-tech, local and global—from farmers, producers, and researchers on six continents.

Source: BBC News