As manager of Unga, a maize miller in the Kenyan capital Nairobi, Dale Wiest seesthe effect that panicked trade restrictions are having on global food prices only too clearly.

Last year he bought half his grain from neighbouring Tanzania. But after a bad harvest, the country banned exports in January. "Since then, we had been unable to purchase there," he says. Maize prices in Kenya are a third higher than a year ago and Mr Wiest is pessimistic. "I think prices will rise more," he says.