Johannesburg - Corn and wheat futures declined in Johannesburg by the midday close.
White corn fell 0.5 percent to 2,157 rand ($201) a metric ton on the South African Futures Exchange. The yellow variety lost 0.04 percent to 2,244 rand a ton.
South Africa is the continent's largest producer of corn. White corn is the source for a meal that's a staple food in the country, while the yellow variety is mainly fed to animals.
Wheat dropped 0.1 percent to 3,901 rand a ton.
The nation is a net importer of wheat and sub-Saharan Africa's largest grower after Ethiopia, according to the U.S. Department of Agriculture.