Robots are revolutionizing America's farmlands. Self-driving tree shakers collect nuts. Mini machines prep soil.And some robots even fire lasers. Their target, unwanted weeds. >> The stuff that's not fun to do, that's going to start to go away.Larry Jacobs runs six farms in California with the help of eight robots that spread fertilizer and flame fields to get rid of insects. >> Our biggest problem is labor. >> You can't find enough people to hire.>> It's challenging to get all the work done because if we d ...