The manufacturing sector, already well developed before UDI in 1965, was given a major stimulus by the imposition of U.N. sanctions. The sanctions obliged Rhodesian industry to diversify and create many import-substitution undertakings to compensate for loss of traditional sources of imports. Rhodesian processing of local raw materials also grew rapidly. Major growth industries include steel and steel products, heavy equipment, transportation equipment, ferrochrome, textiles, and food processing. Agriculture is the backbone of the Zimbabwean economy.
Corn is the largest crop.
Tobacco is the largest export crop followed by cotton. In the early 1970's, the economy experienced a modest boom. Real per capita earnings for blacks and whites reached record highs, although the disparity in incomes between blacks and whites remained, with blacks earning only about one-tenth as much as whites. After 1975, however, Rhodesia's economy was undermined by the cumulative effects of sanctions, declining earnings from commodity exports, worsening guerilla conflict, and increasing white emigration. When Mozambique severed economic ties, the Smith regime was forced to depend on South Africa for access to the outside world.