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,
Crop top gear of American football with no shirt resembles a crop top. Eventually cropped jerseys became available which carried over to several 1980s telecasts. Men also started to wear crop tops regardless of sport. Because of the varied acceptance for men wearing no shirt (eliminating the need for a crop top), and due to a change in school dress codes as well as peer pressure, men usually do not wear crop tops. Various crop tops have been worn by rappers as well as American football athletes. However, in 2015 the NCAA has increased restrictions on men wearing crop tops which also