It is a freakish, doped-up, mutant clone which hasn't had sex for thousands of years - and the strain may be about to tell on the nation's fruitbowl favourite. Scientists based in France have warned that, without radical and swift action, in 10 years' time we really could have no bananas.

Two fungal diseases, Panama disease and black Sigatoka, are cutting a swath through banana plantations, just as blight once devastated potato crops. But unlike the potato, and other crops where disease-resistant strains can be bred by conventional means, making a fungus-free variety of the banana is extraordinarily difficult.

Emile Frison, head of the Montpellier-based International Network for the Improvement of Banana and Plantain, told New Scientist magazine that the banana business could be defunct within a decade. This doesn't just mean we will be eating aubergine splits and that future govern ments may be mocked for policy melon skins. The banana, in various forms, is the staple diet for some half billion people in Asia and Africa.

Almost all the varieties of banana grown today are cuttings - clones, in effect - of naturally mutant wild bananas discovered by early farmers as much as 10,000 years ago. The rare mutation caused wild bananas to grow sterile, without seeds. Those ancient farmers took cuttings of the mutants, then cuttings of the cuttings.

Plants use reproduction to continuously shuffle their gene pool, building up variety so that part of the species will survive an otherwise deadly disease. Because sterile mutant bananas cannot breed, they do not have that protection.

Commercial banana plantations were devastated in the 1950s when Panama disease slew the dominant variety, the Gros Michel. A resistant variety, the Cavendish, filled the gap. But only massive amounts of fungicide spray - 40 sprayings a year is common - now keep Sigatoka at bay, and a new version of Panama disease cannot be sprayed. The Amazon banana crop has been devastated by the fungi, and accord ing to Mr Frison, some parts of Africa now face the equivalent of the Irish potato famine.

One possibility is GM bananas, but growers fear consumer resistance. The big growers are pinning their hopes on better fungicides.

One ray of hope comes from Honduran scientists, who peeled and sieved 400 tonnes of bananas to find 15 seeds for breeding. They have come up with a fungus-resistant variety which could be grown organically. If bananas don't disappear from supermarket shelves by 2013, they will look, and taste, different.