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,
Health measures during the construction of the Panama Canal had died during the construction of the Panama Railway and over 22,000 during the French effort to build a canal. Many of these deaths were due to disease, particularly yellow fever and malaria. At several times, construction on the Panama Railway had actually halted due to the lack of healthy workers. The high rate of deaths among workers on the Panama Canal due to disease was the source of a great deal of controversy in the United States. Newspapers, such as "The Independent", frequently reported on the poor conditions workers in the Canal Zone experienced, including the rampant disease. Poultney