Pesticides are becoming ineffective and fungus are developing resistance very quickly. Modern bananas are sterile, seedless mutants - genetically old with little diversity. The fruit first propagated in the jungles of South East Asia at the end of last ice age.
It's apparently hard to develop genetic variance in asexually reproducing plants. Backcrossing - pollinating with wild plants - is possible but very difficult.
If worst comes to worst, a mass banana extinction may become the next potato blight, like the one which caused the Irish famine in 1840s and there is a similar danger for all monoculture crops.
Scientists are hoping to use biotechnology and genetic manipulation to save the fruit, finding disease-resistant genes from a heartier, non-edible banana variety and insert them in the edible ones.
Half a billion people in Asia and Africa depend on the banana to survive.