While he may have been too ill to attend the Mayday parade in Havana, for only the third time since 1959, Cuban leader Fidel Castro has found the strength to pen yet another diatribe against the current craze for turning food into fuel. His reflections on the sugar harvest are fascinating, but I wonder whether he will have any impact on the rest of the world. And what would he have made of the latest advance: a genetically engineered sorghum, modified to yield better in the long growing seasons of Texas and Kansas.