Monday, June 2, 2008

Banana: R.I.P.

They're in trouble. Can biotechnology save the fruit?
The banana we eat today is not the one your grandparents ate. That one - known as the Gros Michel - was, by all accounts, bigger, tastier, and hardier than the variety we know and love, which is called the Cavendish. The unavailability of the Gros Michel is easily explained: it is virtually extinct.

Introduced to our hemisphere in the late 19th century, the Gros Michel was almost immediately hit by a blight that wiped it out by 1960. The Cavendish was adopted at the last minute by the big banana companies - Chiquita and Dole - because it was resistant to that blight, a fungus known as Panama disease. For the past fifty years, all has been quiet in the banana world. Until now.

Panama disease in Hawaii
Photo: Scot Nelson
Panama disease - or Fusarium wilt of banana - is back, and the Cavendish does not appear to be safe from this new strain, which appeared two decades ago in Malaysia, spread slowly at first, but is now moving at a geometrically quicker pace. There is no cure, and nearly every banana scientist says that though Panama disease has yet to hit the banana crops of Latin America, which feed our hemisphere, the question is not if this will happen, but when. Even worse, the malady has the potential to spread to dozens of other banana varieties, including African bananas, the primary source of nutrition for millions of people.

Crop disease is only half the problem. The other part is denial. One of the most recent places Panama disease struck was Australia. Three years ago, when I was researching my book on bananas, growers down under were bragging that they'd found a way to control the disease, which first appeared in 1997 near the Northern Territory town of Darwin. "We have developed a rapid and accurate DNA-based diagnostic test...used in the detection and management of outbreaks," asserted a brochure issued by the country's Cooperative Research Centre for Plant Protection.

The Australian management program consisted of quick quarantine of fields that were proven by the test to be infected. But early detection doesn't necessarily buy enough time. The plan came apart in March 2006, when Cyclone Larry ravaged Australia's banana growing regions. High winds destroyed more than 85% of the banana crop, and flooding spread infected water and dirt to the surviving banana trees. An October report from the Australia Broadcasting Company documented the rapid spread of the blight on previously-disease free plantations. Reporter Anne Barker wrote that the "industry, which once had such bright prospects, is now facing collapse."

Panama disease hasn't hit our hemisphere yet, and the big banana companies appear unalarmed. Chiquita's 2006 annual report doesn't mention banana disease at all. The company's 2007 end-of-year SEC filing names plant disease as a "risk factor," but only mentions black sigatoka, which can be controlled chemically.

Why should it be? After all, Latin America, where we grow all of our bananas, is a hemisphere away from the places where the disease is now spreading. With all that ocean, could the epidemic could actually reach our bananalands?

Not only is it possible, it might already be happening. In late December, 2007, Philippine agriculture secretary Arthur Yap announced that the U.S. had agreed to import a large shipment of Cavendish bananas from Philippine plantations (overall, we import about 8.5 billion pounds of bananas each year, all from Latin America).

Transgenic plants in field, Uganda
Photo: Rony Swennen
Panama disease is so virulent that a single clump of dirt tracked in on a tire tread or a shoe can spark a country-wide outbreak. It isn't hard to imagine that a stray banana box from the Philippines, loaded into a Dole shipping container could be left unloaded at Long Beach, California, and continue on to Guatemala, where it could infect that nation's crop and tear through Latin America. In fact, the original Panama disease outbreak that decimated the Gros Michel almost certainly went from Asia, to the Caribbean, to Central and South America, though the exact path was never determined. The spread of Panama disease from Asia to the banana plantations of the Western Hemisphere is more than imaginable. With shipping containers traveling the world, and bananas crossing hemispheres, it's likely.

When the first outbreak of Panama disease hit the Gros Michels of South and Central America, it nearly put the entire industry out of business. Only at the last minute was a substitute banana - the Cavendish - found. The Cavendish was thought to be resistant, and for 50 years, that was true. No longer.

Transgenic banana plantlet in Belgian lab
Photo: Dan Koeppel
Now, the future of the Cavendish lies in genetic engineering. Scientists have created bananas that resist Panama disease in the lab. The problem with these engineered bananas is that they lack the other characteristics - ideal ripening speed, a thick skin, and the right taste - that make a banana variety attractive for export. Making a single banana with all of those attributes may take years. Another issue is consumer acceptance: surveys have shown that most shoppers would reject modified bananas, even if they were proven to be safe.

Bananas are, however, excellent candidates for genetic modification. They are sterile - no seeds or pollen by which mutations might spread - and reproduce vegetatively. Right now, regulations have prevented even publicly funded research organizations from testing more than a handful of transformed bananas in the field. Most of this research has been conducted under the auspices of Bioversity International, an umbrella group that works mostly on food security issues. The bananas being field tested were developed by scientists in Leuven, Belgium, and are being grown at experimental plots in Uganda, a country where about 80 percent of some local diets is made up of the fruit, and where the consequences of a banana wipe-out would be disastrous. The millions of people like those in Uganda who depend on bananas to survive would be the real beneficiaries of a better banana.

There's little time left. If there is a "grail banana," it is likely to be found in the lab. The question is whether we'll let it split from there.

Dan Koeppel is the author of Banana: The Fate of the Fruit That Changed the World. He spent three years hanging out with banana growers, scientists, and banana consumers around the world. His website is

1 comment:

FatHer said...

Interesting article.
The progress etc of the disease through Australia would be interesting too.
Earth would have evolved into more of a paradise , if it were not for that 1 most dangerous pest, the human species.