The banana variety nearly wiped out by Panama disease in the mid-20th century was Gros Michel. Also called “Big Mike,” it was the dominant export banana before disease devastated its commercial plantations.
Gros Michel became popular because it was flavorful, productive, and relatively resistant to bruising during shipment. By the early 20th century, Central American plantations and international fruit companies had organized much of the export trade around this single cultivar. That uniformity made the crop especially vulnerable to a soil-borne fungal disease known as Panama disease, caused by Fusarium oxysporum f. sp. cubense.
The disease spread through plantation soils and killed infected plants. By the 1950s, outbreaks had destroyed vast areas of Gros Michel production in Central America, forcing exporters to search for a replacement. They increasingly adopted Cavendish bananas, which were resistant to the strain of Panama disease then affecting Gros Michel and became the supermarket standard.
Gros Michel was not literally eradicated worldwide: it still grows in some disease-free areas and small-scale plantings. Another common confusion concerns modern Panama disease, Tropical Race 4, which threatens Cavendish. The mid-century crisis involved the earlier strain, commonly called Race 1.