Panama disease (or Fusarium wilt) is a plant disease that infects banana plants (Musa spp.). It is a wilting disease caused by the fungus Fusarium oxysporum f. sp. cubense (Foc). The pathogen is resistant to fungicides and its control is limited to phytosanitary measures. During the 1950s, an outbreak of Panama disease almost wiped out commercial Gros Michel banana production. The Gros Michel banana was the dominant cultivar of bananas, and Fusarium wilt inflicted enormous costs and forced producers to switch to other, disease-resistant cultivars. Currently, a new outbreak of Panama disease caused by the strain Tropical Race 4 (TR4) threatens the production of the Cavendish banana, today's most popular cultivar. Overview Although fruits of the wild bananas (Musa spp.) have large, hard seeds, most edible bananas are seedless. Banana plants are therefore propagated asexually from offshoots. Because these rhizomes are usually free of symptoms even when the plant is infected by F. oxysporum f. sp. cubense, they are a common means by which this pathogen is disseminated. It can also be spread in soil and running water, on farm implements or machinery. Panama disease is one of the most destructive plant diseases of modern times. It is believed to have originated in Southeast Asia and was first reported in Australia in 1876. By 1950 it had spread to all the banana-producing regions of the world with the exception of some islands in the South Pacific, the Mediterranean, Melanesia and Somalia. Panama disease affects a wide range of banana cultivars; however, it is best known for the damage it caused to a single cultivar in the early export plantations. Before 1960, a total reliance was put on the cultivar 'Gros Michel', and it supplied almost all the export trade. It proved susceptible to the disease and the use of infected rhizomes to establish new plantations caused widespread and severe losses. Some indication of the scale of the losses is demonstrated by the complete eradication of production on of plantation in the Ulua Valley of Honduras between 1940 and 1960. In Suriname, an entire operation of was out of business within eight years and in the Quepos area of Costa Rica, were destroyed in twelve years. Overall fungal diseases - including most prominently Foc - are disproportionately important to small island developing states. By the middle of the 20th century, resistant cultivars in the 'Cavendish' subgroup were being used as a