CROPS that have been grown and eaten in France for years may soon become illegal. Farmers will no longer be able to plant them and shops won’t be able to sell them.

At least, that is what is supposed to happen later this year. But because it will be virtually impossible to know which varieties are forbidden, it is far from clear how things will pan out.

“I think it’s going to have a real impact on agriculture and plant breeding in France,” says plant biologist Johnathan Napier at Rothamsted Research, UK. It will affect others, too, as France is the largest seed …