Smart weed-killing robots are here and could soon reduce the need for herbicides and genetically modified crops. Swiss company EcoRobotix has a solar-powered robot that can work for up to 12 hours detecting and destroying weeds. Ecorobotix says the robot uses 20 times less herbicide than traditional methods. Blue River Technology has a See and Spray robot that uses a library of images to identify differences between plants and weeds. The robot learns and improves as it operates.