(AP) — In this May 23, 2013, photo, field operations manager Matthew Rossow tests the lettuce bot in Salinas, Calif.
In the Salinas Valley, the lettuce capital of the world, entrepreneurs with the Silicon Valley company Blue River Technology are testing the Lettuce Bot, a boxy robotic machine that can thin fields of lettuce, a job that now requires detailed hand work by 20 farm workers. (AP Photo/Marcio Jose Sanchez)