Crop diversity fruit trees and banana plants) are cloned. A single pest or disease could threaten a whole crop due to this uniformity ("genetic erosion"). A well-known historic case was the Irish Potato Famine of 1845-1847, where a vital crop with low diversity was destroyed by a single fungus. Another example is when a disease caused by a fungus affected the monocultured 1970 US corn crop, causing a loss of over one billion dollars in production. A danger to agriculture is wheat rust, a pathogenic fungus causing reddish patches, coloured by its spores. A virulent form of the wheat disease, stem rust,
Panama disease upwards of 30 years. When the environment is ideal and there are host roots available, these chlamydospores will germinate and hyphae will penetrate the roots, initiating infection. There is in increase in the number of symptomatic plants when inflorescences emerge and the highest disease incidence occurs right before harvest. Once infected, microconidia are produced and present within the vessels of the plant’s vascular system. Macroconidia are another asexual spore that tends to be found on the surface of plants killed by Panama disease. Infection is systemic, moving through the vascular system and causing yellowing and buckling that starts in older