The Economist: LETTUCE is California’s main vegetable crop. The state grew $1.6 billion-worth of the leafy plant in 2010 and accounts for more than 70% of all lettuce grown in America—itself the world’s second-biggest exporter of the stuff. It is a fiddly business. As well as having to be fertilised and weeded, lettuce must also … Continue reading March of the Lettuce Bot