Johannesburg - Wheat increased 1.3 percent to R4,155 a metric ton, the highest settlement price since March 28, 2008, by the midday close on the South African Futures Exchange in Johannesburg.

Wheat reached $7.185 yesterday on the Chicago Board of Trade, the highest since May 13; futures rose 19 percent in March.

"The US winter wheat crop which was planted last year October and is now coming out of dormancy, is experiencing dry conditions coupled with extreme cold spells," Brink van Wyk, a trader at Pretoria-based BVG, said in an e-mailed response to questions. "It is not in good shape."

While South Africa is sub-Saharan Africa's largest grower of the grain after Ethiopia, it's still a net importer of wheat, according to the US Department of Agriculture. The nation's rand weakened to the lowest in more than a week and traded at 10.9429 to the dollar at 2:13pm in Johannesburg.

"The rand weakened sharply overnight, pushing up prices even more," Van Wyk said. "As South Africa is a net importer of wheat, we have no choice but to follow the international price."

White corn gained 1.2 percent to 2,136 rand a ton, while the yellow variety rose 1.2 percent to 2,222 rand a ton.