Contributed by: Don Winner
Only lottery tickets and petrol outsell Britain's favourite fruit - and now a deadly fungus is threatening its existence. Science editor Robin McKie reports on a natural disaster that could change our eating habits, wipe out eco-systems and end a worldwide industry. It is living proof of God's benevolence, say Christians. Convenient for handling and biting, it has a tab for wrapper-removal, a pleasing taste and an obvious sell-by-date mechanism - its skin turns black. Celestial confection-making at its best. And to judge by supermarket figures, this love of the banana is shared by millions. Sales of the fruit have recently reached all-time highs. More than 95 per cent of UK households buy bananas every week. Only lottery tickets and petrol sales outstrip them. Bananas are us, it seems. The trouble is that this popularity is under threat. According to reports by biologists, the banana could be heading down the road to extinction. Or, to be more precise, the Cavendish - the variety sold in shops throughout Britain - may be en route to oblivion. 'We are very concerned,' said Ann Vezina, of the International Network for the Improvement of Banana and Plantain. 'There is no doubt that the Cavendish is facing a real problem.' Virtually all bananas traded internationally are this single variety, but biologists have discovered that several deadly predators -such as the black Sigatoka fungus - are now stalking the Cavendish. The result could be widespread devastation in the world's main plantations of Latin America and Asia, and a corresponding massive rise in the price of the banana.
Pests such as the black Sigatoka are extremely dangerous. However, the real problem lies with the Cavendish, say biologists. It is sexless, seedless and sterile and can only be bred by growing plants from identical cuttings. In short, all Cavendish bananas are genetically identical clones. It's as if every lamp chop sold in a supermarket was derived from fields of Dolly the sheep.
Such similarity spells danger, for plantations of doppelganger bananas lack genetic diversity and are therefore at risk of succumbing to disease. Once a fungus evolves past the natural defences of one set of trees, it will spread like wildfire through the rest.
'At the moment, we have to expend a great deal of effort to fight black Sigatoka, which attacks the banana plant's leaves,' added Vezina. 'Plantations are sprayed intensively with pesticides to keep the disease at bay. More than a third of the price of a banana goes to pay for these pesticides.' However, retailers stress there is no danger posed from these pesticides.
The trouble is that fungi are constantly evolving and trying to bypass the plant's natural defences. Far from illustrating the hand of an 'intelligent designer', the story of the supermarket banana reveals perfectly the working of natural selection.
Indeed, it is exactly this process that did for the Cavendish's predecessor. In the 1950s, Britons ate a different banana from the one now munched at desks, dinner tables and park benches. In those days, the banana of choice was the Gros Michel, until was assailed by Panama disease and was wiped out. Now the Gros Michel is an ex-banana.
And that is what worries biologists and banana fans. The Cavendish could soon follow suit, they fear, and they point out that in some small plantations, managers have discovered that the Panama fungus - to which the Cavendish was supposed to be immune - has begun to attack and kill Cavendish plants.
'The fear is the disease will get into some big plantations, then we will be in trouble,' added Vezina. 'Once the fungus gets in the soil, it cannot be got rid of.'
The impending crisis is akin to the Irish potato famine, say biologists. In the 19th century, Ireland depended on a single variety of potato that was planted over large areas of land and was ravaged by disease in one single outbreak. The current banana crisis shows that the lessons of 'mono-cultures' have not been learnt. Only unsustainable volumes of chemicals are currently keeping black Sigatoka at bay, experts point out.
'One thing we can be sure of is that the Sigatoka won't lose this battle,' said Dr Emile Frison, of the Consultative Group on International Agricultural Research.
In a bid to find a solution to the crisis, scientists are desperately seeking new varieties of wild banana plants that could be grown instead of the Cavendish or whose genes could be introduced to strengthen the Cavendish's ability in its battle against the Panama, Sigatoka, and other diseases.
But these attempts may be doomed to failure, as the UN Food and Agriculture Organisation (FAO) warned this month. It has found that wild banana plants species are being wiped out at an alarming rate as natural forests are destroyed across the sub-continent.
'Due to eco-system destruction, it is probable that many valuable gene sources have now been lost,' said FAO Agricultural Officer NeBambi Lutaladio.
'That could cause serious problems because bananas, particularly commercial varieties, have a narrow genetic pool and are highly vulnerable to pests and diseases.'
In fact, it may now be too late to do anything, he added. Many of the genes which could have saved the Cavendish may already have been lost. For example, India's lost bananas include a variety which is thought able to confer genetic resistance to sigatoka. Today that species exists as a single plant, which is to be found in the Indian Botanic Gardens in Calcutta.
In short, time is running out for the Cavendish. We may not be able to go bananas for much longer.