Gros Michel bananas

Given that each banana variety is propagated clonally, there is very little genetic diversity in the domesticated plants. This makes bananas especially vulnerable to pests and diseases, as a novel pathogen or pest could quickly decimate a variety if it were to exploit a genetic weakness among the clones. Indeed, this very phenomenon occurred in the late 1950s with the Gros Michel dessert variety, which had dominated the world’s commercial banana business. Richer and sweeter than the modern Cavendish, the Gros Michel fell victim to an invading soil fungus that causes Panama disease, a form of Fusarium wilt. Powerless to breed resistance into the sterile clones and unable to rid the soil  of the fungus, farmers were soon forced to abandon the Gros Michel in favour of the hardier Cavendish. Although the Cavendish has thus far been resistant to such a pestilent invasion, its lack of genetic diversity leaves it equally vulnerable to evolving pathogens and pests. Indeed, a strain of Panama disease known as Tropical Race (TR) 4 has been a threat to the Cavendish since the 1990s, and many scientists worry that the Cavendish too will eventually go extinct.