Panama disease has already wiped out one variety of banana. Now a new strain of the fungus threatens further devastation. Is genetic modification the fruit's only chance of salvation?

Most plants, including other types of bananas, reproduce sexually via pollination. This means that the genes of different individuals mix, allowing them to evolve over time. But banana farmers use a different technique: rather than fertilising seeds, they replant the suckers that grow from the stem of the Cavendish plant. This way, its genes don't evolve through reproduction. So the millions of bananas exported every year are all essentially from the same plant.

The asexual Cavendish is a hybrid of two wild plants from South Asia, bred to yield the perfect banana. But as it can't genetically adapt over time, it can't build up a resistance to threats. This leaves it vulnerable to disease.

Clone wars

The Cavendish is not the first banana to monopolise the global market. The Gros Michel (also a clone) was top banana until the 1950s, when crops were ravaged by a fungal infection called Panama disease. As the disease took hold, the Cavendish was selected to replace it because of its genetic resistance.

Now a new soil fungus called Panama disease race 4 is sweeping through Southeast Asia, killing Cavendish bananas as it goes. It's spreading closer to Latin America, where 70% of our bananas are grown. Scientists estimate the Cavendish has around ten years left.

The advantage of the banana monoculture - cultivating a single variety of fruit on a large scale - comes down to profits. Left to its own devices, sexual reproduction could lead to imperfections - and this means waste. Cavendish bananas are cheap to produce and consistently tasty. Yet the monoculture puts them at risk of suffering the same fate as the Gros Michel.

The looming extinction of the Cavendish is worrying: it is responsible for a trade worth over £5bn; and Its demise would have devastating effects on the countries relying on it for livelihoods and nutrition. There's hope a replacement will be developed in time, but so far no disease-resistant and commercially viable replacement exists.

Unnatural selection?

Scientists are desperately working to produce a new, more disease-resistant banana genome. And the search for a solution could take us one step further on the road to artificially designing our perfect fruit: many believe that genetic modification (GM) is the Cavendish's only hope - manipulating its chromosomes to make it disease-resistant. Advocates say GM could help food security in developing countries and reduce the use of disease-fighting pesticidesPoisons used for destroying insects and plants. , which are harmful to the environment.

But millions of consumers in big export markets, including the UK and US, are wary. A survey by Fyffes found that 82% of Britons say they'd never buy a genetically altered banana. And while GM could tackle the problem of the current panama strain, it could just repeat the Cavendish's problem - lacking the genetic diversity to resist new diseases that evolve past it.

Many scientists warn that you can't argue with natural history: genetic diversity is essential to the future of the banana. While some growers try to create a replacement similar to the Cavendish, others are pushing for the introduction of other varieties - of which there are many - to the market. In the long term, they argue, natural variation is a better defence against disease than GM.