PANAMA DISEASE

also called Banana Wilt, a devastating disease caused by the soil-inhabiting fungus species Fusarium oxysporum variety cubense, which is widespread in Asia, Africa, Australia, the Pacific Islands, the Caribbean, Central and South America, and wherever susceptible banana cultivars, such as Gros Michel,' are grown. The Fusarium fungus invades young roots or root bases, often through wounds. Some infections progress into the rhizome (rootlike stem), followed by rapid invasion of the rootstock and leaf bases. Spread occurs through vascular bundles, which become discoloured brown or dark red, and finally purplish or black. The outer edges of older leaves turn yellow. Within a month or two all but the youngest leaves turn yellow, wilt, collapse, and hang downward, covering the trunk (pseudostem) with dead brown leaves. All aboveground parts are eventually killed, although fresh suckers form at the base. These later wilt and the entire stool dies, usually within several years. The Fusarium fungus then continues to thrive in surrounding soil, preventing the success of future plantings. The best long-range control is to breed and grow highly resistant cultivars. See also Fusarium wilt.