Monoculture
Growing one crop, often one genetically identical variety, over large areas: efficient, but a single disease can spread through all of it.
A monoculture is a large area planted with a single crop, often a single variety. It is efficient: every plant ripens at the same time, needs the same care and suits the same machines. The risk is that every plant is also vulnerable to the same pests and diseases, and a dense field of identical hosts lets an outbreak race from plant to plant with nothing to slow it.
The danger is greatest when the plants are clones. Many crops, including bananas and potatoes, are grown from cuttings or tubers rather than seed, so every plant is genetically identical: if a disease can kill one, it can kill them all. Until the 1950s the Gros Michel banana was the main variety grown for export. Panama disease, a wilt caused by the soil fungus Fusarium oxysporum, wiped out vast tracts of Gros Michel plantations in Central America, and by the 1960s exporters had switched to resistant Cavendish varieties, which a newer strain of the same disease now threatens.
In 1970 a fungus swept through the genetically uniform US maize crop, destroying more than a billion dollars' worth of corn.
In wild habitats, plants of one species are usually scattered among others, which makes it far harder for a disease to spread. When Henry Ford planted rubber trees close together in the Amazon, a leaf blight that the scattered wild trees escaped tore through his plantation. Rotating crops, mixing varieties and conserving wild relatives all reduce the risk.
Coming up in future stories
- Henry Ford's Lost Rubber City in the Amazon 1928–1945 · Fordlândia, Pará, Brazil
- The Banana Your Great-Grandparents Ate Is Gone 1950s · Central America
- The Fungus That Turned Ceylon From Coffee to Tea 1870s–1890s · Ceylon (Sri Lanka)
- The Town That Built a Monument to a Pest 1919 · Enterprise, Alabama, USA