The Cavendish banana, the most commonly sold variety worldwide, is facing a growing threat from a soil-borne fungus called Tropical Race 4 (TR4). This disease was first identified in Southeast Asia in the 1990s and has since spread to Australia, Africa, and Latin America. In 2019, TR4 was detected in Colombia, and more recently, in September 2025, Ecuador—home to the world's largest banana exports—confirmed its presence, sparking concern for the global banana supply. TR4 infects banana plants by clogging their internal vascular system, preventing the flow of nutrients and water. The fungus's spores, known as chlamydospores, can remain viable in the soil for up to 40 years, making it extremely difficult to eliminate once it has taken hold. A key vulnerability of the Cavendish banana is its lack of genetic diversity. Unlike most plants, the Cavendish is propagated through vegetative parts called suckers, not seeds. This means all Cavendish bananas are genetically identical, making them highly susceptible to diseases like TR4. This fungus previously devastated the Gros Michel banana variety in the 1950s, forcing the industry to switch to the Cavendish, which was resistant to an earlier strain of the same fungus. However, since the 1990s, TR4 has been spreading and has now reached multiple continents, including Asia, Africa, and South America. TR4 has been confirmed in several countries, including Colombia, Peru, and Venezuela, and is now threatening Martinique. While some regions remain unaffected, such as Guatemala, they are under strict monitoring. In response to the spread of TR4, researchers have been working on solutions. Scientists at Queensland University of Technology have developed genetically modified Cavendish bananas that incorporate a resistance gene from a wild banana species. These modified bananas have shown resistance to TR4 in field tests. In Guadeloupe, researchers are testing non-GM resistant varieties through traditional crossbreeding methods. However, none of these alternatives have yet reached European markets. Despite ongoing research, the Cavendish remains the dominant banana on European shelves, and distributors have not reported any supply disruptions. Martinique, which has so far avoided TR4, continues to rely on strict biosecurity measures to prevent the fungus from entering its territory. While scientists work to develop resistant banana varieties, the global banana industry remains on high alert as the threat of TR4 continues to grow.