The fungus, known as Tropical Race 4 or Panama Disease, has recently been discovered in Jordan and Mozambique after causing major damage in south-east Asia over the past 20 years.
Supplies in the UK have so far been unaffected as we import most of our bananas from Latin American countries including Ecuador, the world’s biggest producer.
However, the UN’s Food and Agriculture Organisation (FAO) warned on Monday that the disease could spread to Latin American banana plantations too.
And Gert Kema, the director of a banana research programme at Wageningen University in the Netherlands, said: “It’s not a question of whether it will arrive but when. There’s no prevention.”
The fungus’ spores stay in the soil for decades so, even if a crop is destroyed, any new bananas grown will also be infected.
So far it affects the Cavendish banana variety, which accounts for 47 per cent of global production.
However, professor Rony Swennen, who manages a plantation in Belgium, says testing for the disease should be expanded to other varieties.
Prof Swennen said: “The export trade will be affected if we stick to the same variety. I think we should start testing many other varieties - with or without the disease threat.”
Prof Swennen called on neighbouring countries to co-ordinate their efforts to fight the spread of the disease together.
He said: “It is only at a country level that we can stop the spread of this disease.”
The fungus is not the only threat to the world’s crop as Costa Rica declared a ‘banana emergency’ due to an outbreak of insects that feed on the fruit, leaving ugly marks on the skin.
Although the bananas are still edible, they do not look good enough for export, a major source of income for the Latin American country.
Bananas are the world’s eighth most important crop and the fourth most important food crop in poor nations, according to the UN.